Media updates on nuclear power stations in Japan

March 16, 2011, 12:20PMANS Nuclear CafeMICHAEL WINES AND MATTHEW L. WALD

For the latest updates on nuclear power stations in Japan, please see the Fukushima tab on the top menu of this page.

A 9.0 magnitude earthquake and resulting tsunami have damaged nuclear power stations in Japan. ANS Nuclear Cafe herein presents a media clip service on breaking news about the status of nuclear energy facilities in Japan. Scroll down for news reports in descending order based on time/date stamps where available or when posted. 

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Updated News & Links

Starting on March 15, updates to the blog will take place twice a day, once mid-morning, and again late afternoon Chicago time. Check for breaking news at the news links above or at Google News.

The reason is that the situation in Japan is evolving so quickly that we think it will be more effective to do two summary level reports rather than overwhelm readers with too much information.

Japan Status Updates 17:30 GMT March 28, 2011

NUCLEAR ENERGY INSTITUTE March 28, 2011, 17:30 GMT

Tokyo Electric Power Co. has detected isolated, low concentrations of plutonium in the soil at the Fukushima Daiichi nuclear power station. The density of plutonium is equivalent to the fallout that reached Japan from nuclear weapons testing during the Cold War, the company said.

TEPCO conducted analysis of plutonium contained in the soil collected on March 21 and 22 at five locations at the Fukushima Daiichi plant. Plutonium 238, 239, and 240 were detected, however just two of the samples may be the direct result of the recent incident, considering the ratio of the plutonium isotopes.

"The density detected in the plutonium is equivalent to the density in the soil under normal environmental conditions and therefore poses no major impact on human health," TEPCO said. The company said it plans to strengthen environmental monitoring inside the station and surrounding areas.

The International Atomic Energy Agency today said it plans to conduct a high-level conference on nuclear safety "before the summer." IAEA Director General Yukiya Amano said it is "vitally important that we learn the right lessons from what happened on March 11, and afterwards, in order to strengthen nuclear safety throughout the world."

Amano said the conference should cover: an initial assessment of the Fukushima accident, its impact and consequences; lessons learned for the industry; strengthening nuclear safety; and strengthening the response to nuclear accidents and emergencies.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 28, 2011, 16:30 GMT Update to Information Sheet Regarding the Tohoku Earthquake

Radiation Levels

  • At 6:00PM (JST, 09:00 GMT) on March 28, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 186 micro Sv/hour.

  • At 6:00PM on March 28, radiation level at west gate (approximate 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 121.6 micro Sv/hour.

  • As of 7:00PM on March 28, the results of the radioactive nuclides detected from the sample of waterhole at the turbine building of each unit of Fukushima Daiichi are as follows:

Unit 1

Unit 2

Unit 3

Unit 4

Date of Samples taken

March 26

March 26

March 26

March 26

Radiation Level on the Surface

60 milli Sv/hour

more than

1,000 milli Sv/hour

750 milli Sv/hour

0.50 milli Sv/hour

Nuclides (half-life)

Concentration (Unit : Bq/cm3)

I-131 (8 days)

1.5 x 105

1.3 x 107

3.2 x 105

3.6 x 102

I-132 (2 hours)

UDL

UDL

UDL

1.3 x 101

I-134 (53 minutes)

UDL

UDL

UDL

UDL

Cs-134 (2 years)

1.2 x 105

2.3 x 105

5.5 x 104

3.1 x 101

Cs-136 (13 days)

1.1 x 104

2.5 x 105

6.5 x 103

3.7 x 100

Cs-137 (30 years)

1.3 x 105

2.3 x 106

5.6 x 104

3.2 x 101

UDL: under the detection limit

  • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 28 are shown here as an English PDF file.

  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 2:30PM on March 26, it was announced that radioactive nuclide I-131 was detected from the sampling of seawater near the seawater discharge point The level of concentration was approximately 1,850 times higher than the maximum permissible water concentration set by the government and it was approximately 1.5 times higher than the previous day's figure.

  • As of 3:10PM on March 27, recovery and transfer work of the waterhole at the turbine building to the condenser by using three pumps was underway.

  • At 3:30PM on March 27, it was announced that 0.4milli (400 micro) Sv/hour was detected on the surface of the waterhole at the trench (concrete tunnel in which the pipes are laid down) outside turbine building.

  • At 12:30PM on March 28, pressure inside the reactor core: 0.376MPa.

  • At 12:30PM on March 28, water level inside the reactor core: 1.75 meters below the top of the fuel rods.

  • At 12:30PM on March 28, pressure inside the primary containmen vessel: 0.270MPaabs.

Fukushima Daiichi Unit 2 reactor

  • At 10:10AM on March26, injection of freshwater in place of seawater into the reactor core started.

  • At 4:46PM on March 26, lighting was restored in the Central Control Room.

  • As of 7:30AM on March 27, transfer work of the waterhole at the turbine building to the condenser was under preparation.

  • At 3:30PM on March 27, it was announced that more than 1,000 milli (1,000,000 micro) Sv/hour was detected on the surface of the waterhole at the trench outside turbine building.

  • At 12:30PM on March 28, the temperature of the spent fuel pool: 121.1 degrees Fahrenheit.

  • At 12:30PM on March 28, pressure inside the reactor core: -0.032MPa.

  • At 12:30PM on March 28, water level inside the reactor core: 1.5 meters below the top of the fuel rods.

  • At 12:30PM on March 28, pressure inside the primary containment vessel: 0.1MPaabs.

  • As of 3:00PM on March 28, the injection of freshwater into the reactor core continues.

  • As of 7:00PM on March 28, approximately 96 tons of water in total has been injected into the spent fuel storage pool.

Fukushima Daiichi Unit 3 reactor

  • As of 7:30AM on March 27, transfer work of the waterhole at the turbine building to the condenser was under consideration.

  • At 12:34PM on March 27, TEPCO began to shoot water aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 2:36PM (approximately 100 tons in total).

  • At 3:30PM on March 27, it was announced that the waterhole was found at the trench outside turbine building, but TEPCO couldn't measure the radiation level on the surface due to rubbles.

  • At 10:30AM on March 28, pressure inside the reactor core: 0.025MPa.

  • At 10:30AM on March 28, water level inside the reactor core: 1.85 meters below the top of the fuel rods.

  • At 10:30AM on March 28, pressure inside the primary containment vessel: 0.1076MPaabs.

  • As of 7:00PM on March 28, approximately 4,597 tons of water in total has been shot to the spent fuel storage pool.

Fukushima Daiichi Unit 4 reactor

  • At 4:55PM on March 27, TEPCO began to shoot water aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 7:25PM (approximately 125 tons in total).

  • As of 7:30AM on March 27, transfer work of the waterhole at the turbine building to the condenser was under consideration.

  • As of 7:00PM on March 28, approximately 960 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:00PM on March 28, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 5 reactor

  • At 2:00PM on March 28, the temperature of the spent fuel pool: 87.6 degrees Fahrenheit.

Fukushima Daiichi Unit 6 reactor

  • At 2:00PM on March 28, the temperature of the spent fuel pool: 86.9 degrees Fahrenheit.

Fukushima Daiichi Common Spent Fuel Pool

  • At 8:00AM on March 27, the temperature of the spent fuel pool: 102.2 degrees Fahrenheit.

  • As of 7:00PM on March 28, approximately 130 tons of water in total has been injected to the spent fuel storage pool.

THE NUCLEAR COMMUNICATIONS NETWORK

News in Brief/No. 83/28 March 2011, 16:00 GMT posted to ANS Nuclear Cafe

Efforts Continue To Restore Off-Site Power

28 Mar (NucNet): Attempts to restore off-site AC power are continuing at the

Fukushima-Daiichi nuclear power plant in Japan and lighting is now available

in the central control rooms of units 1, 2, and 3, the International Atomic

Energy Agency (IAEA) said.

Meanwhile, fresh water is being injected into the reactor pressure vessels

(RPVs) of these three damaged units.

The agency said "no notable change" has been reported in the condition of

unit 4, which was shut down at the time of the earthquake and tsunami on 11

March 2011, and where fuel had already been removed from the reactor.

Units 5 and 6 at the six-unit plant were also shut down at the time of the

quake and have been in "cold shutdown" since last week. Cold shutdown means

the reactors are in a safe mode, with cooling systems stable and under

control, and with low temperature and pressure within the reactor.

At unit 1, pressure in the RPV showed a slight increase, but was stable at

units 2 and 3, possibly indicating that there has been no major breach in

the pressure vessels, the IAEA said.

Graham Andrew, senior adviser to the IAEA's director-general told the BBC

today that concerns about the situation at the plant are "understandable and

well-founded", but noted there had been significant developments such as

electricity being restored to the site, and water and boron being injected

into the RPVs.

He said one of the key things is to avoid reactors becoming "re-critical"

through possible melting of the fuel.

Mr Andrew added: "But there is quite a bit in the plant that the Japanese

and the IAEA do not know, so because of that we have to be cautious with our

assessment."

He said it remains a very serious situation. "We are getting a good flow of

information from the Japanese authorities."

Over the weekend, plant operator Tokyo Electric Power Company (Tepco) began work to remove contaminated water that has accumulated in the turbine

building basements at the plant.

Workers have started to remove water from the unit 1 turbine building to its

main condenser and are preparing to do the same at unit 2. Work to remove

water from the turbine buildings in units 3 and 4 is being considered.

Removal of water from the turbine building basements is an important step

before workers can continue efforts to fully restore power to the plant.

Japan's Nuclear and Industrial Safety Agency (NISA) said high radiation

levels were found in water in the basement of the turbine building of units

1, 2, and 3.

The radiation dose rate on the water surface was 60 millisieverts per hour

(mSv/hr) in unit 1 on Saturday (26 March). In unit 2 it was more than 1,000

mSv/hr, in unit 3 it was 750 mSv/hr, and in unit 4, where little water was

spilled, it was 0.5 mSv/hr.

Iodine-131, which has a half-life of 8.02 days, was the prevailing isotope

in units 2 and 3, and caesium-137 (half-life 30.2 years) in units 1 and 4.

NISA officials believe the contaminated water probably came from the primary

reactor loop rather than the spent fuel pool, because its isotopic

composition indicated it must have been contaminated by leaking fuel

elements that had been recently irradiated. This suggests the RPVs are

seriously damaged.

The IAEA said today that radiation measurements in the containment vessels

and suppression chambers of units 1, 2, and 3 continued to decrease.

Tepco said contaminated water was found in the trenches of units 1 to 3.

Radioactive emissions on the water surface were 0.4 mSv/hr for unit 1 and

more than 1,000 mSv/h for unit 2.

One of the next challenges will be a detailed radiological assessment of the

entire site, after which decisions will take place on what work will follow,

including repairs and cleaning.

Dose Rates Still Falling, Latest Figures Indicate

28 Mar (NucNet): Dose rates at the Fukushima-Daiichi nuclear plant site are

continuing to show a downwards trend, according to the most recent figures.

Recent on-site dose rate monitoring by operator Tokyo Electric Power Company (Tepco) at Fukushima-Daiichi and confirmed by Japan's Nuclear and Industrial Safety Agency (NISA) shows less activity in the air.

Readings had decreased steadily to 128 microsieverts per hour (microSv/hr)

at midnight Japan time on 27 March (16:00, 27 March central European time).

The dose rates measured by Ministry of Education, Culture, Sports, Science

and Technology (MEXT) at a distance of 20 to about 60 km from the plant site

have also continued to fall slightly. On 27 March, only 11 measuring points

of 87 remained above the alarm level of 5 microSv/hr.

In 28 of the 45 prefectures for which data are available, no deposition of

radionuclides was detected in the period 18 to 25 March, the International

Atomic Energy Agency (IAEA) said. In seven of the other 17 prefectures, the

estimated daily deposition was less than 500 becquerel per square metre for

iodine-131 and less than 100 becquerel per square metre for caesium-137.

On 26 March, the highest values were at a hot spot in the prefecture of

Yamagata to the west of the plant site. Those readings showed 7,500

becquerel per square metre for iodine-131 and 1,200 becquerel per square

metre for caesium-137. In the other prefectures where deposition of

iodine-131 was reported, the daily range was from 28 to 860 becquerel per

square metre. For caesium-137, the range was from 2.5 to 86 becquerel per

square metre.

In the Shinjuku district of Tokyo, the daily deposition of iodine-131 on

27 March was 220 becquerel per square metre, while for caesium-137 it was

12 becquerel per square metre. MEXT said that the resulting local dose rate

had yesterday fallen below 0.1 microSv/hr.

New data from monitoring of the marine environment, carried out about 30 km

offshore from 24 March to 25 March, show a decrease in both caesium-137 and

iodine-131. The IAEA said the measured radiation dose rates above the sea

remain consistently low at between 0.04 and 0.1 microsievert per hour.

Recommendations relating to drinking tap water, based on concentrations of

iodine-131, remain in place in seven locations. In Tokyo, the iodine-131

activity in tap water fell below 20 becquerel per kilogramme yesterday,

according to MEXT.

As far as food contamination is concerned, samples taken from 23 to 25 March

in five prefectures showed iodine-131 in unprocessed raw milk, but the

levels were far below the regulation values set by the Japanese authorities.

Caesium-137 was detected in samples of unprocessed raw milk taken on 23

March in Chiba prefecture, to the south of the plant site, but at levels far

below the Japanese regulation values. Caesium-137 was not detected in any of

the samples taken from 24-25 March in the other four prefectures.

Fukushima-Daiichi Nuclear Plant Status Update

28 Mar (NucNet): The following is a summary of the status of all six reactor

units and the spent fuel pools (SFPs) at the Fukushima-Daiichi nuclear

plant.

Unit Status Summary At Fukushima-Daiichi 28 March 2011

Unit 1

Core and fuel integrity: damaged.

Reactor pressure vessel integrity: unknown.

Core cooling requiring AC power: not functional.

Building integrity: severely damaged by hydrogen explosion.

Water level in the rector pressure vessel (RPV): fuel partially or fully

exposed.

Pressure of the RPV: now decreasing after initial increase.

Temperature of the RPV: now decreasing after initial increase.

Water injection to core: continuing. Now using fresh water instead of

seawater.

Water injection to containment vessel: to be confirmed.

Containment venting: temporarily stopped.

Unit 2

Core and fuel integrity: damaged.

Reactor pressure vessel integrity: unknown.

Core cooling requiring AC power: not functional.

Building integrity: slightly damaged.

Water level in the rector pressure vessel: fuel partially or fully exposed.

Pressure of the RPV: unknown.

Temperature of the RPV: stable.

Water injection to core: continuing. Now using fresh water instead of

seawater.

Water injection to containment vessel: to be confirmed.

Containment venting: temporarily stopped.

Unit 3

Core and fuel integrity: damaged.

Reactor pressure vessel integrity: suspected damaged.

Core cooling requiring AC power: not functional.

Building integrity: severely damaged by hydrogen explosion.

Pressure of the RPV: unknown.

Temperature of the RPV: now decreasing after initial increase.

Water injection to core: continuing. Use of fresh water under consideration.

Water injection to containment vessel: to be confirmed.

Containment venting: temporarily stopped.

Unit 4

Shut down at the time of the earthquake, no damage to fuel (which had

already been removed from the reactor and transferred to the pool), core or

containment. Building integrity severely damaged by hydrogen explosion.

Unit 5

Shut down at the time of the earthquake, no damage to fuel, core or

containment. Vent hole opened in roof as precaution against hydrogen

explosion. Unit in cold shutdown.

Unit 6

Shut down at the time of the earthquake, no damage to fuel, core or

containment. Vent hole opened in roof as precaution against hydrogen

explosion. Unit in cold shutdown.

Spent Fuel Pool Status At Fukushima-Daiichi 28 March 2011:

Fuel integrity: unknown at units 1 and 2; possibly damaged at units 3 and 4;

safe at units 5 and 6; safe in the common spent fuel pool.

Unit 1

Seawater injection being considered.

Unit 2

Seawater injection carried out periodically since 20 March.

Unit 3

Water level low, seawater injection continues.

Unit 4

Water level low, seawater injection continues. Reactor building damaged by

explosion and fire on 15 March.

Units 5 & 6

Pool cooling capability recovered.

Common Spent Fuel Pool

Seawater was sprayed over this pool on 21 March. Pool cooling was restarted

after successful installation of an external power supply line on

24 March.

More details

Major Parameters of the Plant

Conditions of Fukushima-Daiichi Nuclear Plant

Reactor Status and Major Events

ASSOCIATED PRESS March 27, 2011, posted to ANS Nuclear Cafe 16:00 GMT Officials: Big spike at Japan nuke plant an error TOKYO -Emergency workers struggling to pump contaminated water from Japan's stricken nuclear complex fled from one of the troubled reactors Sunday after reporting a huge increase in radioactivity - a spike that officials later apologetically said was inaccurate.

The apology came after employees fled the complex's Unit 2 reactor when a reading showed radiation levels had reached 10 million times higher than normal in the reactor's cooling system. Officials said they were so high that the worker taking the measurements had withdrawn before taking a second reading.

On Sunday night, though, plant operators said that while the water was contaminated with radiation, the extremely high reading was a mistake.

"The number is not credible," said Tokyo Electric Power Co. spokesman Takashi Kurita. "We are very sorry."

He said officials were taking another sample to get accurate levels, but did not know when the results would be announced.

The situation came as officials acknowledged there was radioactive water in all four of the Fukushima Dai-ichi complex's most troubled reactors, and as airborne radiation in Unit 2 measured 1,000 millisieverts per hour - four times the limit deemed safe by the government, Kurita said.

Officials say they still don't know where the radioactive water is coming from, though government spokesman Yukio Edano has said some is "almost certainly" seeping from a cracked reactor core in one of the units.

While the discovery of the high radiation levels - and the evacuation of workers from one reactor unit - again delayed efforts to bring the deeply troubled complex under control, Edano insisted the situation had partially stabilized.

"We have somewhat prevented the situation from turning worse," he told reporters Sunday evening. "But the prospects are not improving in a straight line and we've expected twists and turns. The contaminated water is one of them and we'll continue to repair the damage."

The discovery over the last three days of radioactive water has been a major setback in the mission to get the plant's crucial cooling systems operating more than two weeks after a massive earthquake and tsunami.

The magnitude-9 quake off Japan's northeast coast on March 11 triggered a tsunami that barreled onshore and disabled the Fukushima plant, complicating an immense humanitarian disaster.

The death toll from the twin disasters stood at 10,668 Sunday, with more than 16,574 people missing, police said. Hundreds of thousands of people are homeless.

Workers have been scrambling to remove the radioactive water from the four units and find a safe place to store it, TEPCO officials said.

On Sunday night, Minoru Ogoda of Japan's nuclear safety agency said each unit could have hundreds of tons of radioactive water.

The protracted nuclear crisis has spurred concerns about the safety of food and water in Japan, which is a prime source of seafood for some countries. Radiation has been found in food, seawater and even tap water supplies in Tokyo.

Just outside the coastal Fukushima nuclear plant, radioactivity in seawater tested about 1,250 times higher than normal last week - but that number had climbed to 1,850 times normal by the weekend.

Hidehiko Nishiyama, a nuclear safety official, said the increase was a concern, but also said the area is not a source of seafood and that the contamination posed no immediate threat to human health.

Experts with the International Atomic Energy Agency said the ocean would quickly dilute the worst contamination.

Up to 600 people are working inside the plant in shifts. Nuclear safety officials say workers' time inside the crippled units is closely monitored to minimize their exposure to radioactivity, but two workers were hospitalized Thursday when they suffered burns after stepping into contaminated water. They are to be released from the hospital Monday.

Edano has urged TEPCO to be more transparent about the potential dangers after the safety agency revealed the plant operator was aware of high radiation levels in the air in Unit 3 several days before the two workers suffered burns there.

A top TEPCO official acknowledged Sunday it could take a long time to completely clean up the complex.

"We cannot say at this time how many months or years it will take," TEPCO Vice President Sakae Muto said, insisting the main goal now is to cool the reactors.

A poll, meanwhile, showed that support for Japan's prime minister has risen as the administration tackles the disasters.

The public opinion poll conducted over the weekend by Kyodo News agency found that approval of Prime Minister Naoto Kan and his Cabinet rose to 28.3 percent after sinking below 20 percent in February, before the earthquake and tsunami.

Last month's low approval led to speculation that Kan's days were numbered. While the latest figure is still low, it suggests he is making some gains with voters.

About 58 percent of respondents in the nationwide telephone survey of 1,011 people said they approved of the government's handling of the March 11 earthquake and tsunami, but a similar number criticized its handling of the nuclear crisis.

NUCLEAR ENERGY INSTITUTE March 26, 2011, 13:30 GMT

Japanese scientists yesterday detected higher levels radioactive iodine in seawater at water outlets near the Fukushima Daiichi nuclear power plant.

"Iodine 131 was detected at a level 1,250 times the national safety limit," Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said during a news conference. Officials said there is no immediate danger to residents near the plant from these levels.

Samples taken on Friday were significantly higher than those taken on Wednesday, which had 147 times the legal concentration of I-131. Authorities said the concentration of radioactive materials in the water will decrease as the water is diluted by ocean currents. Indeed, a sample taken at 8:50 a.m. on Friday had one-fifth the concentration of I-131 as the earlier measurement. Three subsequent measurements that morning showed fluctuation. All were below the highest level found at 8:30 a.m. on Friday.

"As of now, there is no report of adverse impact on the marine life, especially beyond kilometers [of the plant]," said Chief Cabinet Secretary Yukio Edano. "Experts say there is a very low possibility, but we must strengthen our monitoring."

Efforts to cool the reactors and fuel pools continues at the Daiichi site.Fresh water is now being used to cool reactors 1, 2 and 3 in lieu of seawater. Workers began injecting fresh water at reactors 1 and 3 on March 25 and at reactor 2 on March 26. Meanwhile, two U.S. Navy barges carrying 500,000 gallons fresh water are en route to a port 37 miles south of the Fukushima plant.

NUCLEAR ENERGY INSTITUTE 23:00 GMT,  March 25

Fresh water is being injected into the reactor pressure vessel at reactor 3 at Fukushima Daiichi nuclear power plant, Japan's Nuclear and Industrial Safety Agency said.

TEPCO said that radioactive materials discovered at the reactor 3 turbine building possibly came from water from the reactor system, not the spent fuel pool. TEPCO made that statement after collecting samples of contaminated water in the reactor 3 turbine building and conducting a gamma-emitting nuclide analysis of the sample. The reactor pressure and drywell pressure at reactor 3 remained stable on Friday, leading TEPCO to believe that "the reactor pressure vessel is not seriously damaged.

Cooling efforts at Reactor 1 already had switched back to fresh water cooling. Reactor 2 is still being injected with seawater, but is expected to switch to fresh water soon.

Tokyo Electric Power Co. said that crews continued spraying water into the used fuel storage pools at reactors 3 and 4 on Friday to keep the used uranium fuel rods safe. Also on Friday, the heat removal system at reactor 6 was switched to a permanent power supply, NISA added.

TEPCO said it was assessing the radiation dose to two workers who were contaminated while laying cable in the turbine building of reactor 3. TEPCO said it had instructed its employees and contract workers to pay attention to their personal radiation dosimeter alarms and evacuate when necessary.

On-site radiation monitoring at the Fukushima Daiichi nuclear power plant indicates that radiation dose rates continue to decrease, theInternational Atomic Energy Agency said.

Radiation Monitoring Update

Air and seawater sampling continues by the Japanese government. Measurements in the ocean were taken 30 kilometers off-shore and 330 meters from the discharge points on March 23 and March 24. Results indicate concentrations of iodine-131 at 2,162 picocuries per liter and cesium-137 at approximately 703 picocuries per liter. Adult consumption of 1,000 picocuries (1 picocurie is one-trillionth of a curie) per liter concentration for 30 days will result in 24 millirem of radiation dose. For comparison, a typical dose from a chest x-ray is 10 millirem.

The concentrations found in the seawater samples are most likely "due to atmospheric fallout rather than just ocean currents," IAEA said. Dilution is expected to rapidly decrease this surface contamination, IAEA added.

Iodine-131 was detected in drinking water in 13 prefectures and cesium-137 was detected in drinking water in six prefectures. All results remained below the limits set by the Japanese government, IAEA said. Iodine-131 levels in drinking water in Tokyo are now below limits for consumption by infants set by the Japanese authorities and restrictions have been lifted.

On March 25, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 kilometers from the Fukushima Daiichi nuclear power plant. At these locations, the radiation dose rate was at extraordinarily low

NUCLEAR ENERGY INSTITUTE March 25, 2011, 17:30 GMT

Workers have switched from sea water to fresh water to cool reactor 1 and were expected to make the same change for reactors 2 and 3 at the Fukushima Daiichi nuclear power plant by Saturday. Pressure and temperature inside reactor 1 were declining on Friday.

Lighting has been restored in the control rooms of reactors 1 through 4 at the plant, which lost electric power after the March 11 earthquake and tsunami, the Japan Atomic Industrial Forum said. With offsite electric service connected to all the units, workers are attempting to connect plant safety equipment. Some pumps and other equipment that were damaged in the earthquake and tsunami must be repaired or replaced.

Water spraying to maintain cooling of used uranium fuel rods in the reactor 3 used fuel storage pool was suspended because of high radiation levels near that building, but spraying into the reactor 1 and 4 storage pools continued.

Reactors 5 and 6 are safely shutdown and are being cooled with pumps using offsite electricity.

Radiation dose rates at the Fukushima Daiichi site boundary continue to range from 1 millirem to 3 millirem per hour.

MINISTRY OF EDUCATION, CULTURE, SPORTS, SCIENCE AND TECHNOLOGY-JAPAN March 25 2011, posted to ANS Nuclear Cafe at 17:30 GMT  Click here for information on concentration measurements in the stagnant water in the basement of the turbine building of Fukushima Daiichi-1.

INTERNATIONAL ATOMIC ENERGY AGENCY March 25, 2011, 15:30 GMT

On Friday, 25 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

There has not been much change at the Fukushima Daiichi plant over the last 24 hours. Some positive trends are continuing, but there remain areas of uncertainty that are of serious concern.

Unit 1 is with offsite AC power to the lighting of its central control room and to some of its instrumentation. Unit 3 now also has lighting to its central control room, but not power to its instrumentation. It remains too early to evaluate how much instrumentation may effectively be recovered at Units 1, 2, 3 and 4.

Reactor pressure is decreasing at Unit 1 and so is seawater injection. On the other hand, pressure readings in the reactor pressure vessels remain unreliable in Unit 2 and have become unreliable in Unit 3.

The temperature at the feed-water nozzle of the reactor pressure vessel continues to decrease (to 205 degrees C) at Unit 1, and at Unit 3 (42.8 degrees C), and it remains stable at Unit 2 (105 degrees C).

The dose rates in the containment vessel and suppression chamber have continued to decrease at Unit 1, and remained stable at Unit 2.

At Unit 3, radiation exposure of three TEPCO subcontracting workers has been confirmed. They were working in the basement, with contaminated water on the floor. Two of them were transferred to hospital with contamination of their feet.

There are no significant developments to report at Unit 4, where water spraying continues.

Units 5 and 6 remain in comparatively good condition. Temperatures at both, which had risen when the cooling pumps were briefly shut down in order to switch to off-site power, temperatures have since been restored to lower levels, and both units are still in cold shutdown. For the same reasons, a brief rise in temperature also occurred at the Common Spent Fuel Pool on 24 March.

2. Radiation Monitoring

On-site radiation monitoring at the Daiichi NPP indicates that dose rates continue to decrease.

Deposition of radioactivity is monitored daily by Japanese authorities in all 47 prefectures. From 23 March to 24 March, additional deposition has been detected in 7 of the 47 prefectures. Considerable variations are observed, the deposition at this day ranged from 42 to 16,000 Becquerel per square metre for iodine-131; the highest value determined for caesium-137 was 210 Becquerel per square metre. For the Shinjuku district of Tokyo, the deposition of iodine-131 on this day increased by 13,000 Becquerel per square metre, and the caesium-137 deposition by 160 Becquerel per square metre.

As far as the marine environment is concerned, sampling of air and seawater continues to be carried out by the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT). Results are sent to the IAEA Monaco laboratory for assessment.

Measurements in the marine environment have been carried out 30 km off-shore and 330 metres from the discharge points on 23 March and repeated the next day. The results made available up to 25 March indicate concentrations of iodine-31 (some 80 becquerel/litre) and caesium-137 (about 26 becquerel/litre). This contamination is most likely due to atmospheric fallout rather than just ocean currents. Dilution in the ocean is expected to decrease rapidly this initial surface contamination. Caesium-137 will be more important over the long term owing to its half-life (30 years) compared to that of iodine-131 (8 days). Modelling of the dispersion of these radionuclides has been started, and the first results are becoming available. Marine dispersion will of course be much slower than atmospheric transport.

Since yesterday, additional data has been made available by the Japanese authorities concerning radionuclide concentrations in milk, vegetables and drinking water.

Levels of iodine-131 exceeded levels recommended by the Japanese authorities in five raw milk samples taken in Fukushima Prefecture, and exceeded levels of iodine-131 and cesium-137 in one vegetable (mizuna) sampled in Ibaraki Prefecture.

Monitoring of drinking water is on-going, iodine-131 in drinking water was detected in 13 prefectures, caesium-137 was detected in 6 of the 47 prefectures. During the period of 19 to 23 March, all results remained below the limits set by the Japanese government. However, permissible levels of iodine-131 were exceeded in drinking water samples taken in the Fukushima and Ibaraki Prefectures and in Tokyo from 17 to 23 March. More positively, the iodine-131 levels in drinking water for Tokyo are now below limits for consumption for infants recommended by the Japanese authorities and restrictions have been lifted.

As a result of food monitoring where contamination exceeded the levels recommended by the Japanese authorities, current restrictions on the distribution of milk are in place in 2 prefectures (Fukushima, Ibaraki) and on the distribution of certain vegetables in 4 prefectures (Fukushima, Ibaraki, Tochigi, Gunma). This regulatory approach is to prevent food contaminated with radioactivity above these limits entering the market and thereby, ensure the safety of foods. On 23 March, the Japanese authorities requested sampling of agricultural products in 6 neighbouring prefectures (Miyagi, Yamagata, Saitama, Chiba, Niigata and Nagano). This request for further food monitoring covers the same types of foods currently under restriction.

The joint FAO/IAEA food safety mission is currently travelling to Japan.

On 25th March, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 km from the Fukushima nuclear power plant. At these locations, the dose rate ranged from 0.73 to 8.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.07 to 0.96 Megabecquerel per square metre.

Director General Amano had a video conference today with the UN Secretary General and the Heads of a number of other UN system organizations concerning the accident. In addition, close coordination led by the IAEA through the Joint Radiation Emergency Management Plan of International Organizations (JPLAN) continues.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 25, 2011, 15:00 GMT

Update to Information Sheet Regarding the Tohoku Earthquake

Radiation Levels

  • At 7:00PM (JST) on March 25, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 199.5 micro Sv/hour.

  • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 25 are shown by clicking here to access the English PDF file.

  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started and at 3:37PM, the injection of freshwater into the reactor core started.

  • At 2:00PM on March 25, pressure inside the reactor core: 0.342MPa.

  • At 2:00PM on March 25, water level inside the reactor core: 1.65 meters below the top of the fuel rods.

  • At 2:00PM on March 25, pressure inside the primary containment vessel: 0.280MPaabs.

Fukushima Daiichi Unit 2 reactor

  • At 10:00AM on March 25, the temperature of the spent fuel pool: 82.4 degrees Fahrenheit.

  • At 10:30AM on March25, TEPCO began to inject seawater into the spent fuel pool via cooling and purification line, until at 12:19PM (approximately 38 tons in total).

  • At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started.

  • At 2:00PM on March 25, pressure inside the reactor core: -0.016MPa.

  • At 2:00PM on March 25, water level inside the reactor core: 1.4 meters below the top of the fuel rods.

  • At 2:00PM on March 25, pressure inside the primary containment vessel: 0.12MPaabs.

  • As of 7:00PM on March 25, approximately 96 tons of water in total has been injected into the spent fuel storage pool.

  • As of 7:00PM on March 25, external power generation is connected and the functionality of the electric devices is being checked.

  • As of 7:30PM on March 25, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 3 reactor

  • At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started and at 6:02PM, the injection of freshwater into the reactor core started.

  • At 1:28PM on March 25, Kawasaki City Fire Department began to shoot water aimed at the spent fuel pool until 4:00PM (approximately 450 tons in total).

  • At 2:00PM on March 25, pressure inside the reactor core: 0.038MPa.

  • At 2:00PM on March 25, pressure inside the primary containment vessel: 0.1089MPaabs.

  • At 2:10PM on March 25, water level inside the reactor core: 1.9 meters below the top of the fuel rods.

  • As of 7:00PM on March 25, approximately 4,497 tons of water in total has been shot to the spent fuel storage pool.

Fukushima Daiichi Unit 4 reactor

  • At 6:05AM on March25, TEPCO began to inject seawater into the spent fuel pool via cooling and purification line, until at 10:20APM.

  • At 7:05PM on March 25, TEPCO began to shoot water aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete.

  • As of 7:00PM on March 25, approximately 685 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:00PM on March 25, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 5 reactor

  • At 3:00PM on March 25, the temperature of the spent fuel pool: 98.4 degrees Fahrenheit.

  • At 3:00PM on March 25, the temperature of the water in the reactor core: 129.0 degrees Fahrenheit.

Fukushima Daiichi Unit 6 reactor

  • At 3:00PM on March 25, the temperature of the spent fuel pool: 69.8 degrees Fahrenheit.

Fukushima Daiichi Common Spent Fuel Pool

  • As of 7:00PM on March 25, approximately 130 tons of water in total has been injected to the spent fuel storage pool.

NUCLEAR ENERGY INSTITUTE March 25, 2011, 13:30 GMT

Japanese officials are investigating the source of higher radiation readings at reactor 3 at the Fukushima Daiichi nuclear power plant after two workers were contaminated while laying cable in the turbine building. Tests of the water in which the workers were standing contained a concentration of radioactive material many times the level normally found in water circulating in the reactor, the Nuclear and Industrial Safety Agency said.

"When we looked into the composition of the water, the source...seems to be the reactor core," said NISA's Hidehiko Nishiyama. "Another possibility is the spent fuel, and we cannot rule out that possibility either."

Several possibilities could account for the presence of radioactive materials in the turbine building. Seawater sprayed onto the fuel pool area may have washed over the floor of the fuel pool area onto the turbine building and leaked through the damaged roof into the basement of that building. Other possibilities include a problem with an interconnected system to the primary containment, such as the main steam system, or a small opening in the reactor containment structure.

Japanese authorities recommended residents within 30 kilometers of the plant evacuate voluntarily, extending the recommendation from 20 kilometers. Damage to infrastructure in the area from the earthquake severely limits the ability to provide water, food and other necessary supplies to people sheltering in their homes for the coming weeks.

Tokyo Electric Power Co. is stepping up efforts to switch from sea water to fresh water for cooling the reactors and used fuel storage pools. The United States government has urged the switch to fresh water as soon as possible and is providing two U.S. Navy barges, each of which can carry up to 1,000 tons of water. The ships are scheduled to reach port about 60 kilometers from the Daiichi plant in about three days. Japanese workers at the site will install pipes and hoses to carry the water to the plant.

New Web Page on 'Health and Radiation'

NEI has created a new web page, "Health and Radiation Safety," which provides information and links to additional resources.

JAPAN ATOMIC INDUSTRIAL FORUM March 25, 2011, 12:00 GMT  Click here for latest JAIF status of Fukushima Daiichi nuclear power plants.

TOKYO ELECTRIC POWER COMPANY March 25, 2011, 06:00 GMT

Click here for information on status of TEPCO's facilities and its services after Tohoku-Taiheiyou-Oki earthquake.

INTERNATIONAL ATOMIC ENERGY AGENCY March 25, 2011, 05:15 GMT Fukushima Nuclear Accident Update - Update on Conditions of Fukushima Daiichi Nuclear Power Plant

  • At Unit 1 workers have advanced the restoration of off-site electricity and lighting in the Unit's main control room was recovered as of 24 March, 11:30 UTC. They are now checking the availability of the cooling system. While the pressure in the reactor vessel remains high, Japanese authorities are reporting that it has stabilized.

  • At Unit 2 engineers are working for the recovery of lighting in the main control room, and the instrumentation and cooling systems.

  • At Unit 3, around 120 tonnes of seawater was injected in the spent fuel pool via the cooling and purification line. The operation was carried out between 23 March, 20:35 UTC and 24 March, 07:05 UTC. Work was under way for the recovery of the instruments and cooling systems. However, it had to be suspended because three workers were exposed to elevated levels of radiation on 24 March.

  • At Unit 4, the spent fuel pool was sprayed with around 150 tonnes of water using concrete pump truck. The operation was carried out between 24 March, 05:36 UTC and 06:30 UTC of the same day.

  • At Units 5 and 6, repair of the temporary pump for Residual Heat Removal (RHR) was completed as of 24 March, 07:14 UTC, and cooling started again 21 minutes later.

  • At the Common Spent Fuel, the power supply was restored as of 24 March, 06:37 UTC and cooling started again 28 minutes later. Work is now under way for the recovery of the lighting and instrumentation systems. As of 24 March, 09:40 UTC, the water temperature of the pool was around 73 °C.

As of 24 March, 10:30 UTC workers continue to inject seawater into the reactor pressure vessels of Units 1, 2 and 3 and are preparing to inject pure water.

NUCLEAR ENERGY INSTITUTE March 24, 2011, 23:00 GMT Restoration of electric power at reactors 1, 2, and 4 at the Fukushima Daiichi nuclear power plant has led to the reconnection of important reactor instrumentation, the International Atomic Energy Agency said.

Cooling water continues to be injected into reactors 1, 2, and 3. Reactors 5 and 6 at Fukushima Daiichi remain safely shut down. Both reactors were undergoing maintenance at the time of the earthquake.

Radiation dose rates inside the containment vessels of reactors 1 and 2 have decreased slightly, IAEA said.

External power has been reconnected to the common used fuel storage pool at the plant and cooling started on March 24 at 5:05 a.m. EDT, according to Japan's Nuclear and Industrial Safety Agency. About 60 percent of the used uranium fuel rods at Fukushima plant are stored at this facility.

Radiation Monitoring Continues

Air samples collected at on-site monitors at the Fukushima Daiichi plant March 19-23 show that only iodine-131 was found to be in excess of Japanese government limits. Radiation dose rates measured on site March 21-23 have decreased from 193 millirem to 21 millirem per hour. Radiation dose rates at the plant's site boundary ranged from 1 millirem to 3 millirem per hour on Thursday.

At distances between 34 and 73 kilometers to the west of the Fukushima Daiichi nuclear power plant, the dose rate ranged from .06 millirem to .69 millirem per hour.

Considerable variation in the levels of reported iodine-131 and cesium-137 continues in 10 prefectures, IAEA said. Food, milk and drinking water sampling has been most thorough and extensive in the Fukushima and Ibaraki prefectures, IAEA said.

Seawater samples collected at several points 30 kilometers from the coastline near the Fukushima Daiichi nuclear power plant found measurable concentrations of iodine-131 and cesium-137, IAEA said. The iodine concentrations were at or above Japanese regulatory limits. The cesium levels were well below those limits.

For more information on iodine-131, see NEI's fact sheet Health Impacts of Iodine-131.

THE NUCLEAR COMMUNICATIONS NETWORK

News in Brief/No. 80/March 24, 2011, posted at ANS Nuclear Cafe 17:00 GMT  US plans 'two-pronged review' of nuclear plant safety

(NucNet): Commissioners at the US Nuclear Regulatory Commission

(NRC) today voted to launch a two-pronged review of US nuclear power plant

safety in the aftermath of the March 11 earthquake and tsunami and the

resulting events at the Fukushima-Daiichi nuclear power plant in Japan.

The commission supported the establishment of an agency task force that will

conduct both short-term and long-term analysis of the lessons that can be

learned from the situation in Japan. The results of their work will be made

public.

The longer-term review will decide on any permanent NRC regulation changes

that are needed, the NRC said.

The commission said it expects that the task force can begin the long-term

evaluation in no later than 90 days, and added that the task force should

provide a report with recommended actions within six months of the beginning

of that effort.

NRC inspectors at US nuclear power plants will also support the task force's

short-term effort, supplemented as necessary by experts from the agency's

regional and headquarters offices, the NRC said.

"Examining all the available information from Japan is essential to

understanding the event's implications for the United States NRC chairman

Gregory Jaczko said.

"We will perform a systematic and methodical review to see if there are

changes that should be made to our programs and regulations to ensure

protection of public health and safety."

TOKYO ELECTRIC POWER COMPANY March 24, 2011, posted at ANS Nuclear Cafe at 15:40 GMT                                                                                               Results of nuclide analyses of radioactive materials in the air at the site of Fukushima Daiichi nuclear power plant

REUTERS March 24, 2011, 15:33 GMT Japan says must review nuclear power policy as crisis persists Japan will have to review its nuclear power policy, its top government spokesman said on Thursday as radiation from a damaged nuclear complex briefly made Tokyo's tap water unsafe for babies and led to people emptying supermarket shelves of bottled water.

Engineers are trying to stabilize the six-reactor nuclear plant in Fukushima, 250 km (150 miles) north of the capital, nearly two weeks after an earthquake and tsunami battered the plant and devastated northeastern Japan, leaving nearly 26,000 people dead or missing.

"It is certain that public confidence in nuclear power plants has greatly changed," Japanese Chief Cabinet Secretary Yuki Edano told Reuters.

"In light of that, we must first end this situation and then study from a zero base."

Before last week, Japan's 55 nuclear reactors had provided about 30 percent of the nation's electric power. The percentage had been expected to rise to 50 percent by 2030, among the highest in the world.

There were no fresh incidents of smoke or steam at the plant on Thursday, but four of the plant's reactors are still considered volatile, although on the way to stability.

"It's still a bit early to make an exact time prognosis, but my guess is in a couple of weeks the reactors will be cool enough to say the crisis is over," said Peter Hosemann, a nuclear expert at the University of California, Berkeley.

"It will still be important to supply sufficient cooling to the reactors and the spent fuel pools for a longer period of time. But as long as this is ensured and we don't see any additional large amount of radioactivity released, I am confident the situation is under control."

Tokyo's 13 million residents were told not to give tap water to babies under 1 year old after contamination hit twice the safety level this week. But it dropped back to allowable amounts on Thursday.

Despite government appeals against panic, many supermarkets and stores sold out of bottled water.

"Customers ask us for water. But there's nothing we can do," said Masayoshi Kasahara, a store clerk at a supermarket in a residential area of eastern Tokyo. "We are asking for more deliveries but we don't know when the next shipment will come."

Radiation above safety levels has also been found in milk and vegetables from Fukushima and the Kyodo news agency said radioactive cesium 1.8 times higher than the standard level was found in a leafy vegetable grown in a Tokyo research facility.

Singapore said it had found radioactive contaminants in four samples of vegetables from Japan.

Earlier, it and Australia joined the United States and Hong Kong in restricting food and milk imports from the zone, while Canada became the latest of many nations to tighten screening after the world's worst nuclear crisis since Chernobyl.

A shipping industry official, meanwhile, said some merchant vessels may be avoiding Tokyo port due to concern that crew members may be exposed to radiation.

Click here to read complete article.

NUCLEAR ENERGY INSTITUTE March 24, 2011, 13:30 GMT

Two workers were hospitalized for radiation exposure Thursday, even as Tokyo Electric Power continued to make progress in stabilizing reactors at the Fukushima Daiichi nuclear power plant.

Three workers received radiation exposure of 17 to 18 rem from standing in contaminated water while laying cable in the reactor 3 turbine building, TEPCO said. One of the workers did not require hospitalization. The exposures were less than the 25 rem emergency dose limit established by the Japanese government.

External electric power was restored to reactor 1 and lights were on in the control room. Lighting was restored to the reactor 3 control room Wednesday. Electric power also has been connected to some of the instruments in all reactors except unit 3. While external electricity is available at all six units, it is not in wide use as workers inspect and repair cooling equipment before it can be energized. Reactors 5 and 6 have been safely shut down with cooling systems running on offsite power.

Seawater is being injected to cool the cores of reactors 1, 2 and 3. Workers continue to spray water into the spent fuel pools of reactors 3 and 4.

In Tokyo, the level of radioactive iodine in tap water has dropped to within safety limits Thursday. Yesterday, the Japanese government had advised against giving tap water to infants under one year old.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 24, 2011, 15:00 GMT

Update to information regarding the Tohoku earthquake

Radiation Levels

  • At 6:30PM (JST) on March 24, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 204.5 micro Sv/hour.

  • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 24 are shown by clicking here for English PDF file.

  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 10:50AM on March 24, hazy white steam was emitted from the top of the second containment building.

  • At 11:30AM on March 24, lighting was restored in the Central Control Room.

  • At 1:00PM on March 24, pressure inside the reactor core: 0.423MPa.

  • At 1:00PM on March 24, water level inside the reactor core: 1.7 meters below the top of the fuel rods.

  • At 1:00PM on March 24, pressure inside the primary containment vessel: 0.39MPaabs.

  • As of 7:30PM on March 24, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 2 reactor

  • At 1:00PM on March 24, pressure inside the reactor core: -0.023MPa.

  • At 1:00PM on March 24, water level inside the reactor core: 1.15 meters below the top of the fuel rods.

  • At 1:00PM on March 24, pressure inside the primary containment vessel: 0.11MPaabs.

  • At 1:00PM on March 24, the temperature of the spent fuel pool: 113 degrees Fahrenheit.

  • As of 6:00PM on March 24, approximately 58 tons of water in total has been injected into the spent fuel storage pool.

  • As of 6:00PM on March 24, external power generation is connected and the functionality of the electric devices is being checked.

  • As of 7:30PM on March 24, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 3 reactor

  • At 11:30PM on March 23, it was confirmed that the emission of black smoke had ceased (confirmed again at 4:50AM on March 24).

  • At 5:35AM on March 24, TEPCO began to inject seawater into the spent fuel pool via cooling and purification line, until at 4:05PM (approximately 120 tons in total).

  • At 10:20AM on March 24, pressure inside the reactor core: 0.036MPa.

  • At 10:20AM on March 24, water level inside the reactor core: 1.9 meters below the top of the fuel rods.

  • At 10:20AM on March 24, pressure inside the primary containment vessel: 0.107MPaabs.

  • At 2:25PM on March 24, the radiation level near the power panel of the 1st basement floor of turbine building was measured as 200 milli Sv per hour.

  • As of 6:00PM on March 24, approximately 3,927 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:30PM on March 24, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 4 reactor

  • At 2:36PM on March 24, TEPCO began to shoot water aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 5:30PM (approximately 150 tons in total).

  • As of 6:00PM on March 24, approximately 685 tons of water in total has been shot to the spent fuel storage pool.

  • As of 6:00PM on March 24, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 5 reactor

  • At 1:00PM on March 24, the temperature of the spent fuel pool: 117.9 degrees Fahrenheit.

  • At 1:00PM on March 24, the temperature of the water in the reactor core: 197.6 degrees Fahrenheit.

Fukushima Daiichi Unit 6 reactor

  • At 1:00PM on March 24, the temperature of the spent fuel pool: 80.6 degrees Fahrenheit.

Fukushima Daiichi Common Spent Fuel Pool

  • At 3:37PM on March 24, the external power started to be supplied.

  • As of 6:00PM on March 24, approximately 130 tons of water in total has been injected to the spent fuel storage pool.

  • As of 6:05PM on March 24, cooling of the spent fuel pool began.

  • At 6:40PM on March 24, the temperature of the spent fuel pool: 163.4 degrees Fahrenheit.

JAPAN ATOMIC INDUSTRIAL FORUM March 24, 2011, 12:00 GMT  Click here for latest JAIF status of Fukushima Daiichi nuclear power plants.

MINISTRY OF EDUCATION, CULTURE, SPORTS, SCIENCE AND TECHNOLOGY-JAPAN March 24, 2011, 10:58 GMT                                         Click here for readings of environmental radioactivity levels by Japanese prefecture.

MINISTRY OF EDUCATION, CULTURE, SPORTS, SCIENCE AND TECHNOLOGY-JAPAN March 24, 2011,01:00 GMT                               Readings at monitoring post out of Fukushima Daiichi nuclear power plant by vehicle-borne survey.

NUCLEAR ENERGY INSTITUTE March 23, 2011, 23:00 GMT

Commissioners at the U.S. Nuclear Regulatory Commission on Wednesday voted to launch a two-pronged review of U.S. nuclear power plant safety in the aftermath of the March 11 earthquake and tsunami and the resulting events at the Fukushima Daiichi nuclear power plant.

The commission supported the establishment of an agency task force that will conduct both short- and long-term analysis of the lessons that can be learned from the situation in Japan. The results of their work will be made public.

"The longer-term review will inform any permanent NRC regulation changes" that are needed, the NRC said. The commission said it expects that the task force can begin the long-term evaluation in no later than 90 days and added that the task force should provide a report with recommended actions within six months of the beginning of that effort.

NRC inspectors at U.S. nuclear power plants will also support the task force's short-term effort, supplemented as necessary by experts from the agency's regional and headquarters offices, the NRC said.

"Examining all the available information from Japan is essential to understanding the event's implications for the United States. We will perform a systematic and methodical review to see if there are changes that should be made to our programs and regulations to ensure protection of public health and safety," NRC Chairman Gregory Jaczko said.

Fukushima Daiichi

Smoke seen coming from the reactor building at reactor 3 at 4:20 p.m. on Wednesday (Japan time) "decreased significantly," the International Atomic Energy Agency said. On Wednesday, smoke from reactor 3 caused the temporary evacuation of workers from reactors 3 and 4.

Efforts are continuing to restore off-site electricity at reactors 1, 2, 3 and 4.

As reported earlier here, seawater injection continues to cool reactors 1, 2 and 3. Seawater is being sprayed into the reactor 3 spent fuel pool. Crews continued to use a truck to deliver high volumes of water into the spent fuel pool at reactor 4, IAEA said.

REUTERS March 23, 2011, 21:52 GMT                                                                         IAEA: Japan plant worker received high radiation VIENNA (Reuters) - One of the workers struggling to avert a disaster at Japan's crippled nuclear plant was exposed to a high radiation dose that may increase the risk of cancer, a U.N. atomic agency official said Wednesday.

Japanese authorities have also told the International Atomic Energy Agency (IAEA) two prefectures near the crippled plant- Chiba and Ibarak-were advised to monitor seafood products, the official, Graham Andrew, said.

High levels of radioactive iodine and cesium were measured close to water discharge points at the Fukushima power plant, "before dilution by the ocean," he told a news conference.

Japanese authorities tested seawater off the plant's site for radiation Tuesday, but stressed elevated levels already detected were no cause for worry.

In a desperate attempt to cool the reactors and their spent fuel ponds, workers have sprayed or dumped sea-water into the plant's cooling system. Officials have acknowledged some of the water spilled back to sea.

The plant has still not been brought under control, and workers were forced away from the complex when black smoke began rising from one of its six reactors Wednesday. The IAEA said it had not received any information about the incident.

IAEA defends role

Andrew said Japanese authorities had told the agency radiation dose rates at the plant were decreasing, but suggested iodine and cesium contamination in nearby areas had risen.

The IAEA also had information about eighteen workers at the site which had been exposed to radiation since the accident, including one who got a dose rate of about 0.1 sieverts (106.3 millisieverts), although no medical treatment was required.

The agency did not say when it happened. The average dose for a nuclear plant worker is 50 millisieverts over five years.

The operator of Fukushima said last week it had raised the limit for the emergency work to 100 millisieverts an hour.

"The 0.1 sievert which you have there is certainly not a low dose and the individual may have a greater risk of certain cancer in the future...So it is something to be avoided, it is a high dose," Andrew said.

A senior former IAEA official, Olli Heinonen, has criticized the initial response of his former employer to the crisis, saying its early reports after the March 11 earthquake provided scant, and at times contradictory information from Japan.

The IAEA has said it could only give the information to its member states it itself received from Japan.

NHK WORLD March 23, 2011, 21:49 GMT                                                          TEPCO: Black smoke rises from No.3 reactor

The Tokyo Electric Power Company (TEPCO) says black smoke was seen rising from the No.3 reactor building at the quake-damaged Fukushima Daiichi nuclear plant at around 4:20 PM (JST) on Wednesday.

TEPCO told reporters that it received a report 1 hour later that the smoke had gradually cleared.

The company said that the level of radiation near the main gate of the plant, 1 kilometer west of the No.3 reactor, was 265.1-microsieverts-per-hour at 5 PM. They added there had been no major change in the levels after the smoke was observed.

On Monday afternoon, gray smoke was seen rising from the same reactor building. TEPCO said that the plumes turned white before disappearing.

The power company evacuated workers from the control room of the No. 3 reactor, as well as firefighters from Tokyo and Yokohama preparing for a water-spraying operation.

The firefighters had to abandon their planned water spraying operation for the day.

NUCLEAR ENERGY INSTITUTE March 23, 2011, 18:30 GMT

The U.S. Food and Drug Administration has blocked the import of milk, milk products, and fresh vegetables and fruits produced in areas surrounding the Fukushima Daiichi nuclear power plant. FDA is flagging all shipments from Japan to determine whether they originated from the affected area. The agency will test all food and feed shipments from areas near the plant.

Earlier, the Japanese government stopped the sale of raw milk, spinach and kakina (a local vegetable) from areas near the station.

Workers at the Daiichi site continue to inspect equipment to determine whether it can be connected to off-site power sources, which is now available at all six reactors. Off-site power has replaced the use of an emergency diesel generator to provide cooling to reactors 5 and 6, which had been shut down before the earthquake.

Seawater injection continues to cool reactors 1, 2 and 3, and seawater is being sprayed into the reactor 3 spent fuel pool. Water spray continues on the spent fuel pools at reactors 1, 3 and 4.

Radiation dose rates at the Daiichi site boundary continue to range from 1 to 3 millirem per hour.

NEI has posted its Health Impacts of Iodine-131 fact sheet.

NUCLEAR STREET March 23, 2011, posted at 18:15 GMT to ANS Nuclear Cafe                                                                                                                                             Close-up video on YouTube of damage at Fukushima Daiichi and the water-pumping efforts.

WORLD NUCLEAR NEWS March 23, 2011, posted to ANS Nuclear Cafe at 18:00 GMT, originally posted to WNN site on March 22 at 13:08 GMT and updated at 16:01 GMT.

Casualties among power plant workers

  • Two Tepco employees have minor injuries.

  • Two contractors were injured when the quake struck and were taken to hospital, one suffering two broken legs.

  • A Tepco worker was taken to hospital after collapsing and experiencing chest pains.

  • A subcontract worker at an "important earthquake-proof building" was found unconscious and was taken to hospital.

  • Two Tepco workers felt ill whilst working in the control rooms of Fukushima Daiichi units 1 and 2 and were taken to the medical centre at Fukushima Daini.

  • Four workers were injured in the hydrogen explosion at Fukushima Daiichi 1. They were all taken to hospital.

  • Eleven workers (four Tepco workers, three subcontract workers and four members of Self Defence Force) were hurt following a similar explosion at Fukushima Daiichi 3. They were transferred to the Fukushima Daini plant. One of the Tepco employees, complaining of pain in his side, was later transferred to hospital.

  • The whereabouts of two Tepco workers, who had been in the turbine building of Fukushima Daiichi unit 4, is unknown.

  • Only one casualty has been reported at the Fukushima Daini plant. A worker in the crane operating console of the exhaust stack was seriously injured when the earthquake struck. He subsequently died.

Contamination and radiation cases

  • One Tepco worker working within the reactor building of Fukushima Daiichi unit 3 during "vent work" was taken to hospital after receiving radiation exposure exceeding 100 mSv, a level deemed acceptable in emergency situations by some national nuclear safety regulators.

  • Another six Tepco workers have since received radiation doses in excess of the usual 100 mSv emergency allowance. One has received more than 150 mSv.

  • Nine Tepco employees and eight subcontractors suffered facial exposure to low levels of radiation. They did not require hospital treatment.

  • Two policemen were decontaminated.

  • An unspecified number of firemen who were exposed to radiation are under investigation.

THE NUCLEAR COMMUNICATIONS NETWORK News in Brief/No. 77/ 23 March 2011, posted 15:30 GMT to ANS Nuclear Cafe

  • Tepco Makes Progress In Bid To Restore External Power

  • IAEA on radiation measurements at Fukushima

23 Mar (NucNet): Tokyo Electric Power Company (Tepco) is continuing its

efforts to restore external AC power to all six units at Fukushima-Daiichi

nuclear power plant, with external power now available at units 2, 4, 5 and

6, the Japan Atomic Industrial Forum (JAIF) said.

JAIF said "integrity checks" of electrical equipment are being carried out

in each unit and these must be completed before energising them.

In unit 3, the lights have been turned on in the control room area and

backup batteries for essential instrumentation and control systems are

operational. Tepco technicians are testing the pump integrity of the

residual heat removal system for the reactor and spent fuel pool (SFP)

cooling. JAIF said this was "encouraging news".

JAIF also said the residual heat removal system was being energised with

external power in unit 5.

According to Japan's Nuclear and Industrial Safety Agency (NISA) unit 6 has

had AC power for the residual heat removal system since 19:17 Japan time on

22 March 2011 (11:17 central European time) and lights were turned on in

unit 3 at 22:43 Japan time.

Without electrical power, cooling systems at Fukushima-Daiichi's six

reactors cannot operate. Many of the problems facing the nuclear power plant

stem from the loss of electrical power at the site following the massive

earthquake and tsunami on 11 March. The earthquake cut off external power to

the plant and the tsunami disabled backup diesel generators.

The International Atomic Energy Agency (IAEA) said restoring external power

to the plant does not mean the reactors will immediately resume normal

safety function. The earthquake and tsunami may have inflicted considerable

damage in addition to knocking out electricity supplies, the agency said.

"Because the extent of this damage is unknown, it is not possible to

accurately estimate a work schedule."

JAIF also said today that pressure and temperature in the reactor pressure

vessel (RPV) of unit 1 has increased to a very high level and more seawater

injection was necessary. NISA said the injection rate was increased at 02:33

Japan time on 23 March from 2 cubic metres per hour to 18 cubic metres per

hour.

NISA said about 180 tonnes of seawater was sprayed onto the SFP of unit 3

yesterday by the Tokyo Fire Department, and  about 150 tonnes of seawater

was sprayed onto the SFP of unit 4 yesterday evening.

On 21 March, work had resumed on pumping seawater into the RPV and primary

containment vessels (PCVs) at units 2 and 3 after it was suspended on 20

March when smoke was detected and it was decided to evacuate personnel from

the reactor buildings.

Defence minister Toshimi Kitazawa said that because of the smoke from units

2 and 3 a helicopter would continue to take daily measurements of the

surface temperature at these units.

Seawater spraying onto the SFPs of units 2, 3 and 4 is continuing.

According to NISA and Tepco, radioactivity readings from monitoring posts on

the Fukushima-Daiichi site and at the site boundary have been more or less

constant since yesterday afternoon until today at 08:30. At the main gate at

11:10 today (Japan time) the reading was 226.8 microsieverts per hour

(microSv/hr) and to the north of the service building on 21 March at 16:30

it was 2015 microSv/hr.

Tepco has published the results of environmental analysis of seawater from a

sample taken next to the plant yesterday (22 March) at 06:30 local time. The

results are as follows:

  • cobalt-58: 17,000 becquerel per cubic-metre (0.02 times the regulatory limit);

  • iodine-131: 1,200,000 becquerel per cubic-metre (30 times the regulatory limit; yesterday 127 times);

  • iodine-132: 1,400,000 becquerel per cubic-metre (0.5 times the regulatory limit);

  • cesium-134: 150,000 becquerel per cubic-metre (2.5 times the regulatory limit; yesterday 25 times);

  • cesium-136: 24,000 becquerel per cubic-metre (0.1 times the regulatory limit);

  • cesium-137: 150,000 becquerel per cubic-metre (1.7 times the regulatory limit; yesterday 17 times).

The IAEA has confirmed that Tepco's monitoring will be checked using

independent samples taken by the Japan Agency for Marine-Earth Science and

Technology (Jamstec) and the Japan Atomic Energy Agency (JAEA).

IAEA Briefing On Lack Of Data And Radiation Monitoring Results

23 Mar (NucNet): The International Atomic Energy Agency (IAEA) has said

essential data on water levels and temperatures are lacking from units 1, 2,

3 and 4 of Fukushima-Daiichi and further measurements are needed to assess

contamination.

The IAEA said in a technical briefing on 21 March 2011 that following the

restoration of cooling at units 5 and 6, temperatures in those spent fuel

pools continue to decline. The agency said it was seeing some steady

improvements, but the overall situation at the Fukushima-Daiichi nuclear

power plant remains "very serious".

High levels of contamination have been measured in the locality of the

plant, the briefing said.

The IAEA said restoration of electrical power to unit 2, which was reported

on 20 March 2011, is good news. "AC power is available and an electrical

load check to pumps etc. is currently on-going," the briefing said.

Seawater is still being injected into the reactor pressure vessels of units

1, 2 and 3. Pressure in the reactor pressure vessel and the

containment-vessel drywell at unit 3, which had been rising on 21 March, has

fallen.

Radiation Monitoring

The IAEA also said its radiation monitoring team had taken measurements at

distances from 56 to 200 km from the Fukushima nuclear power plant. At two

locations in Fukushima Prefecture, gamma dose rate and beta-gamma

contamination measurements have been repeated. These measurements showed

high beta-gamma contamination levels, the IAEA said.

Measurements by the IAEA and the Japanese authorities were taken at the same

time and locations. And both sets of measurements gave comparable results.

Measurements of gamma dose rate and beta-gamma contamination were taken on 20 March at more locations.

The dose-rate results ranged from 2 to160 microsieverts per hour

(microSv/hr), which compares to a typical natural background level of around

0.1 microSv/hr. High levels of beta-gamma contamination have been measured

between 16 and 58 km from the plant. Results show contamination ranging from

0.2-0.9 megabecquerels (MBq) per square metre.

The agency said: "Further measurements are needed to assess possible

contamination beyond the area currently monitored - both closer to the

facility and further away."

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 23, 2011, 14:00 GMT

Radiation Levels

  • At 6:30PM (JST) on March 23, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 249 micro Sv/hour.

  • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 23 are shown in a PDF file available by clicking here.

  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 2:33AM on March 23, amount of seawater injection has increased by using water supply system in addition to water extinction system (from 2 cubic meter per hour to 18 cubic meter per hour).

  • At 2:00PM on March 23, pressure inside the reactor core: 0.376MPa.

  • At 2:00PM on March 23, water level inside the reactor core: 1.7 meters below the top of the fuel rods.

  • At 2:00PM on March 23, pressure inside the primary containment vessel: 0.345MPaabs.

  • As of 2:00PM on March 23, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 23, external power generation is connected through Unit 2 and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 2 reactor

  • At 4:07PM on March 22, TEPCO began to inject seawater into the spent fuel storage pool, until 5:01PM (approximately 18 tons in total).

  • At 4:20AM on March 23, the temperature of the spent fuel pool: 123.8 degrees Fahrenheit.

  • At 2:00PM on March 23, pressure inside the reactor core: -0.036MPa.

  • At 2:00PM on March 23, water level inside the reactor core: 1.25 meters below the top of the fuel rods.

  • At 2:00PM on March 23, pressure inside the primary containment vessel: 0.11MPaabs.

  • As of 2:00PM on March 23, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 23, approximately 58 tons of water in total has been injected into the spent fuel storage pool.

  • As of 7:00PM on March 23, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 3 reactor

  • At 10:46PM on March 22, lighting was restored in the Central Control Room.

  • At 9:10AM on March 23, pressure inside the reactor core: -0.104MPa.

  • At 9:10AM on March 23, water level inside the reactor core: 1.8 meters below the top of the fuel rods.

  • At 9:10AM on March 23, pressure inside the primary containment vessel: 0.1MPaabs.

  • At 11:00AM on March 23, TEPCO began to inject water into the spent fuel pool, until 1:20PM (approximately 35 tons in total).

  • At 4:20PM on March 23, black smoke was emitted from the secondary containment building. (Under investigation)

  • As of 2:00PM on March 23, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 23, approximately 3,927 tons of water in total has been shot to the spent fuel storage pool.

Fukushima Daiichi Unit 4 reactor

  • At 5:17PM on March 22, TEPCO began to shoot water aimed at the spent fuel pool, until 8:32PM, with a specialized vehicle normally used for pumping concrete (approximately 150 tons in total).

  • At 10:00AM on March 23, TEPCO began to shoot water aimed at the spent fuel pool, until 1:02PM, with a specialized vehicle normally used for pumping concrete (approximately 130 tons in total).

  • As of 7:00PM on March 23, approximately 535 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:00PM on March 23, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 5 reactor

  • At 7:41PM on March 22, it was confirmed that power supply was completely switched form diesel generator to external power.

  • At 2:00PM on March 23, the temperature of the spent fuel pool: 102.2 degrees Fahrenheit.

Fukushima Daiichi Unit 6 reactor

  • At 7:41PM on March 22, it was confirmed that power supply was completely switched form diesel generator to external power.

  • At 2:00PM on March 23, the temperature of the spent fuel pool: 67.1 degrees Fahrenheit.

JAPAN ATOMIC INDUSTRIAL FORUM March 23, 2011, 12:00 GMT  Click here for latest JAIF status of Fukushima Daiichi nuclear power plants.

TOKYO ELECTRIC POWER COMPANY March 23, 2011, 08:00 GMT  Click here for an in-depth report on the status of TEPCO's facilities and services after Tohoku-Taiheiyou-Oki earthquake.

NUCLEAR ENERGY INSTITUTE March 22, 2011, 23:00 GMT

Tokyo Electric Power Co. reported on March 22 that it had restored electricity to the control room at the Fukushima Daiichi reactor 3. Lights in the control room were switched on for the first time since the earthquake 11 days ago. Electricity to the reactor 4 control room is expected to be restored shortly.

Power restoration to the control rooms will help technicians as they seek to repair the two reactors' cooling systems. Workers are seeking to reactivate control room monitoring systems for reactor parameters, such as reactor coolant temperatures and water levels. The company also reported that thermometers at reactors 1, 2, and 3 are working again.

TEPCO said it would try to reactivate a cooling pump for reactor 3 later on March 22 or March 23. The company said that if the pump functions normally, it could begin cooling the reactor and the spent fuel storage pool.

Workers at the Fukushima Daiichi plant also continued to spray water into the used fuel pools of reactors 3 and 4. A 160-foot long extension arm normally used to pour concrete for high-rise buildings was used to more accurately spray water into the used fuel pool area of reactor 4. Workers also pumped 18 tons of seawater into the reactor 2 used fuel pool.

Japan's health ministry says it detected radioactive iodine levels in tap water above the national safety standard for infants at five locations in Fukushima Prefecture. The agency says the water does not pose an immediate risk to infants, but is advising against consumption of the water or adding water to powdered milk for infants.

Elevated levels of radioactive iodine and cesium were detected in soil about 25 miles from Fukushima Daiichi, but the levels do not pose a health risk, according to Japan's science ministry.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 22, 2011,  14:00 GMT

  • Radiation Levels

  • At 2:30PM (JST) on March 21, it was announced that radioactive nuclides have been detected from the sampling of seawater near the seawater discharge point of Unit 1 to 4 (south side). The details of radioactive nuclides, concentration, and the maximum permissible water concentration set by the government are as follows:

Radioactive Nuclides

Concentration (Bq/cm3)

Maximum Permissible Water Concentration (Bq/cm3)

Co-58

5.955 x 10-2

1 x 100

I-131

5.066 x 100

4 x 10-2

I-132

2.136 x 100

3 x 100

Cs-134

1.486 x 100

6 x 10-2

Cs-136

2.132 x 10-1

3 x 10-1

Cs-137

1.484 x 100

9 x 10-2

At 03:30PM on March 22, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 277.5 micro Sv/hour.

Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 22 are shown in

the attached PDF file. English version is available by clicking here.

For comparison, a human receives 2,400 micro Sv per year from

natural radiation in the form of sunlight, radon, and other sources. One

chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 11:20AM on March 22, pressure inside the reactor core: 0.227MPa.

  • At 11:20AM on March 22, water level inside the reactor core: 1.8 meters below the top of the fuel rods.

  • At 11:20AM on March 22, pressure inside the primary containment vessel: 0.175MPaabs.

  • As of 6:00PM on March 22, the injection of seawater into the reactor core continues.

  • As of 4:00PM on March 22, external power generation is connected through Unit 2 and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 2 reactor

  • At 11:20AM on March 22, pressure inside the reactor core: -0.018MPa.

  • At 11:20AM on March 22, water level inside the reactor core: 1.35  meters below the top of the fuel rods.

  • At 11:20AM on March 22, pressure inside the primary containment vessel: 0.11MPaabs.

  • At 11:20AM on March 22, the temperature of the spent fuel pool: 127.4 degrees Fahrenheit.

  • As of 4:00PM on March 22, roughly 40 tons of water in total has been injected into the spent fuel storage pool.

  • As of 4:00PM on March 22, external power generation is connected and the functionality of the electric devices is being checked.

  • As of 6:00PM on March 22, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 3 reactor

  • At 10:35AM on March 22, pressure inside the reactor core: -0.101MPa.

  • At 10:35AM on March 22, water level inside the reactor core: 1.575 meters below the top of the fuel rods.

  • At 10:35AM on March 22, pressure inside the primary containment vessel: 0.100MPaabs.

  • At 2:10PM on March 22, the Tokyo Fire Department began to shoot water aimed at the spent fuel pool.

  • As of 4:00PM on March 22, roughly 3,742 tons of water in total has been shot to the spent fuel storage pool.

  • As of 4:00PM on March 22, external power generation is connected through Unit 4 and the functionality of the electric devices is being checked.

  • As of 6:00PM on March 22, the injection of seawater into the reactor core continues.

Fukushima Daiichi Unit 4 reactor

  • As of 4:00PM on March 22, roughly 255 tons of water in total has been shot to the spent fuel storage pool.

  • As of 4:00PM on March 22, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 5 reactor

  • At 11:00AM on March 22, the temperature of the spent fuel pool: 99.5 degrees Fahrenheit.

  • As of 4:00PM on March 22, external power generation is connected and the power supply has been switched from Diesel Generator.

Fukushima Daiichi Unit 6 reactor

  • At 11:00AM on March 22, the temperature of the spent fuel pool: 77 degrees Fahrenheit.

  • As of 4:00PM on March 22, external power generation is connected and the functionality of the electric devices is being checked (Spent fuel pool is being cooled by the power supplied from Diesel Generator of Unit 6).

Fukushima Daiichi Common Spent Fuel Pool

  • At 4:30PM on March 21, the temperature of the spent fuel pool: 141.8 degrees Fahrenheit.

NUCLEAR ENERGY INSTITUTE March 22, 2011, 13:30 GMT

Tokyo Electric Power Co. has reconnected external power supply at Fukushima Daiichi reactors 1, 2, 5, and 6. Offsite electricity is providing power to cooling pumps for the used fuel pools at reactors 5 and 6. Components and circuits at reactors 1 and 2 are being checked before power is restored to them. The company on Tuesday was installing cable at reactor 4 and power is expected to be restored at reactors 3 and 4 on Wednesday (Japan time).

TEPCO said the radiation level at the main gate at Fukushima Daiichi has declined from 33 millirem per hour to 25 millirem per hour.

Fire departments on Tuesday continued to pump water into the used fuel pools at reactors 3 and 4. Seawater is being pumped through a manually laid hose and sent to a water truck for continual spraying. Firefighters have sprayed a total of 3,600 tons of seawater, or about three times the pool's capacity, in recent days.

Japan's Chief Cabinet Secretary, Ukiyo Edano, reported the detection of low levels of iodine 131 and cesium 137 in seawater near the plant. There is no threat to human health, officials said.

Prime Minister Naoto Kan has ordered the governors of four prefectures (Fukushima, Ibaraki, Gunma and Tochigi) to suspend shipments of spinach and milk from specified areas. However, Kan said the levels of airborne radiation in those areas pose no risk to human health.

The Fukushima Daini reactors remain in safe condition today.

JAPAN ATOMIC INDUSTRIAL FORUM March 22, 2011, 13:00 GMT  Click here for latest JAIF status of Fukushima Daiichi nuclear power plants.

TOKYO ELECTRIC POWER COMPANY March 22,2011, 09:00 GMT

Status of Fukushima Daiichi Nuclear Power Station For detailed status, please click here.

TOKYO ELECTRIC POWER COMPANY March 22,2011, 09:00 GMT

Status of Fukushima Daini Nuclear Power Station

  • Unit 1

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Unit 2

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint

  • Unit 3

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Unit 4

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Other  N.A.

NUCLEAR ENERGY INSTITUTE March 21, 2011, 22:30 GMT

Japan's NHK broadcasting network reported that Tokyo Electric Power Co. confirmed that the March 11 earthquake and tsunami were beyond the Fukushima Daiichi plant's design standards.

TEPCO believes the tsunami that inundated the Fukushima Daiichi site was 14 meters high, the network said. The design basis tsunami for the site was 5.7 meters, and the reactors and backup power sources were located 10 to 13 meters above sea level. The company reported that the maximum earthquake for which the Fukushima Daiichi plants were designed was magnitude 8. The quake that struck March 11 was magnitude 9.

Smoke seen from Fukushima Daiichi reactor 3 on Monday subsided after about two hours. Water pressure and levels at the reactor were unchanged through the episode, as were radiation levels, the company said.

The site was temporarily cleared of workers after smoke rose from at the secondary containment buildings that house reactors 2 and 3. The Nuclear and Industrial Safety Agency said the smoke from reactor 2 caused radiation levels downwind to rise for about three and a half hours.

TEPCO continues work to reconnect external power to all six reactors. Connections were made to the distribution line at reactor 1 and 2, and components and circuits at those reactors are being checked. Similar power connections have been made to reactors 5 and 6 and a diesel generator is providing power to a cooling pump for the used fuel pools. Power cable is being laid to reactor 4, and power is expected to be restored to reactors 3 and 4 by Tuesday.

Japan's Chief Cabinet Secretary Yukio Edano announced that Prime Minister Kan has ordered the governors of four prefectures near Fukushima to restrict the shipment of spinach and "kakina," another leafy vegetable. The shipment of milk from Fukushima prefectures was also restricted. Edano said the order was a precautionary emergency measure.

INTERNATIONAL ATOMIC ENERGY AGENCY March 21, 18:15 GMT Japanese authorities have reported that they will measure radioactivity in the marine environment around the Fukushima Daiichi nuclear power plant. The monitoring will be conducted from 22-23 March by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Sea water sampling from eight locations will be sampled and analysed by the Japan Atomic Energy Agency (JAEA), and results will be provided on 24 March. The analysis will include radionuclide concentrations found in sea water and dose rate. The IAEA will continue to follow this information.

WORLD NUCLEAR NEWS March 21, 2011, originally published 17:22 GMT, updated 20:48 GMT                                                                                                        Radiation levels in the wider area around the Fukushima Daiichi nuclear power plant trended downwards for several days, but have recently increased on rainfall. Contamination of food appears limited at present.

Conditions for workers on the plant site have been alleviated somewhat in the last few days thanks to successful efforts to refill fuel ponds. But safety considerations there are on a wholly different scale from those in nearby areas already evacuated or further afield in cities such as Tokyo.

According to the Research Organisation for Information Science and Technology, a typical person in Japan receives an average radiation dose of about 3750 microsieverts per year. Some 60% of this is voluntarily received from medical procedures - such as X-rays and CT scans. A CT scan of the chest can contribute some 7000 microsieverts, according to Japan's Ministry of Education, Culture, Sports, Science, and Technology (MEXT).

A nuclear worker by contrast is allowed to receive a dose of up to 20,000 microsieverts per year, although in practice they often receive very much less. In emergency situations it is acceptable for workers to receive up to 100,000 microsieverts. Below this it is statistically difficult to connect radiation dose to cancer rates, but above this the relationship starts to become apparent. An exception has been made in the current crisis to allow emergency workers to receive exposures up to 250,000 microsieverts. Only one worker involved in a steam venting operation some days ago has been confirmed to have received more than the 100,000 microsievert level.

Click here to read complete story.

FEDERATION OF ELECTRIC POWER COMPANIES March 21, 2011, 15:00 GMT

Radiation Levels

  • At 04:30PM (JST, 06:30 GMT) on March 21, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 2,015 micro Sv/hour.

  • At 06:30PM on March 21, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 1,932 micro Sv/hour.

  • Measurement results of ambient dose rate around Fukushima Nuclear Power Station announced at 1:00PM and 4:00PM on March 21 are shown in the attached two PDF files respectively.

  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.

Fukushima Daiichi Unit 1 reactor

  • At 2:25PM on March 21, pressure inside the reactor core: 0.198MPa.

  • At 2:25PM on March 21, water level inside the reactor core: 1.75 meters below the top of the fuel rods.

  • At 2:25PM on March 21, pressure inside the primary containment vessel: 0.16MPaabs.

  • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 2 reactor

  • At 2:25PM on March 21, pressure inside the reactor core: -0.023MPa.

  • At 2:25PM on March 21, water level inside the reactor core: 1.35 meters below the top of the fuel rods.

  • At 2:25PM on March 21, pressure inside the primary containment vessel: 0.12MPaabs.

  • At 2:25PM on March 21, the temperature of the spent fuel pool: 122.0 degrees Fahrenheit.

  • At 6:22PM on March 21, steam was emitted from the secondary containment building. (Under investigation)

  • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 3 reactor

  • At 9:30PM on March 20, the Tokyo Fire Department began to shoot water aimed at the spent fuel pool, continuously until 3:58AM on March 21 (roughly 1,137 tons in total).

  • At 12:25PM on March 21, pressure inside the reactor core: -0.083MPa.

  • At 12:25PM on March 21, water level inside the reactor core: 1.6 meters below the top of the fuel rods.

  • At 12:25PM on March 21, pressure inside the primary containment vessel: 0.120MPaabs.

  • At 3:55PM on March 21, gray smoke was emitted from the secondary containment building.

  • At 4:49PM on March 21, the gray smoke changed to white smoke, but the volume of the smoke was unchanged.

  • At 6:02PM on March 21, it was confirmed that the emission of smoke had ceased.

  • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.

  • As of 7:00PM on March 20, about 3,742 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:00PM on March 21, activities for connecting an external power supply are underway.

Fukushima Daiichi Unit 4 reactor

  • At 6:22PM on March 20, 10 Self Defense Force vehicles began to shoot water aimed at the spent fuel pool, until 7:43PM (roughly 81 tons in total).

  • At 6:37AM on March 21, 12 Self Defense Force vehicles and TEPCO began to shoot water aimed at the spent fuel pool, until 8:41AM (in total about 91 tons). TEPCO used one high pressure water cannon supplied by the US Army.

  • As of 7:00PM on March 21, roughly 83 tons of water in total has been shot to the spent fuel storage pool.

  • As of 7:00PM on March 21, activities for connecting an external power supply are underway.

Fukushima Daiichi Unit 5 reactor

  • At 4:00PM on March 21, the temperature of the spent fuel pool: 108.1 degrees Fahrenheit.

  • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Unit 6 reactor

  • At 7:27PM on March 20: cold shutdown

  • At 4:00PM on March 21, the temperature of the spent fuel pool: 96.8 degrees Fahrenheit.

  • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.

Fukushima Daiichi Common Spent Fuel Pool

  • From 10:37AM to 3:30PM on March 21, roughly 130 tons of water in total has been injected into the spent fuel storage pool.

JAPAN ATOMIC INDUSTRIAL FORUM March 21, 2011, 13:00 GMT  Click here for latest JAIF status of Fukushima Daiichi nuclear power plants.

TOKYO ELECTRIC POWER COMPANY March 21, 2011, 12:00 GMT     Plant status of Fukushima Daini Nuclear Power Station

[No new developments since 09:00 GMT, March 21]

  • Unit 1

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Unit 2

  • Reactor cold shutdown, stable water level, offsite power is  available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Unit 3

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Unit 4

  • Reactor cold shutdown, stable water level, offsite power is available.

  • No cooling water is leaked to the reactor containment vessel.

  • Maintain average water temperature at 100°C in the pressure restraint.

  • Other  N.A.

The next information in regard to the plant is planned to be released

at 9:00 am JST, 22nd March.

JAPAN ATOMIC INDUSTRIAL FORUM March 21, 2011, 12:00 GMT

Here is information regarding the status of Fukushima Daiichi nuclear power station according to the Nuclear and Industrial Safety Agency.

  • Work to recover external AC power is in progress at unit-1 through -6. External AC power cable has already been connected to the distribution switchboards at unit-1 and -2. Power Center at unit-2 received electricity (15:46 JST, March 20 ) and the integrity of each load is being confirmed. AC power will be provided to these units after current inspection to check problem. Works for laying electricity cable to the Power Center at unit-4 was completed around 15:00 on March 21.

  • The pressure of the Reactor Containment Vessel at unit 3 of Fukushima Daiichi rose once (320 kPa as of 11:00 March 20th) and dropped later. Monitoring the pressure continues (120 kPa as of 12:15 March 21).

And at 18:00 (09:00 GMT) on March 21, Chief Cabinet Secretary Edano announced:

  • After detecting radioactive material being beyond the government's regulatory standard from spinach and kakina, the Prime Minister Kan ordered the governors of Fukushima, Ibaraki, Tochigi and Gunma prefectures that shipment of these vegetables would be restricted "for the time being". The shipment of milk from Fukushima prefecture was also restricted. Edano repeatedly emphasized that it was an emergency measure just in case and they would have no harm to the health of people who ingest them.

MINISTRY OF EDUCATION, CULTURE, SPORTS, SCIENCE AND TECHNOLOGY-JAPAN March 21, 2011, 11:37 GMT                                        Click here for readings of environmental radioactivity levels by Japanese city.

NUCLEAR ENERGY INSTITUTE March 21, 2011,  01:30 GMT

Fukushima Daiichi

Tokyo Electric Power Co. continued efforts on Monday to restore power to its reactors at Fukushima Daiichi as well as stabilize cooling in the used fuel pools of some reactors. Reactors 1, 2, and 3 are in stable condition and reactors 5 and 6 are stable and being cooled by systems powered by electricity that was restored over the weekend.

The Tokyo Fire Department sprayed cooling water into the reactor 3 used fuel pool for about 4.5 hours, ending early Monday morning. At reactor 4, Japan's Self-Defense Force sprayed water into the pool for about two hours. Overall, 13 fire engines have been used in the spraying. Efforts to spray water into the used fuel pools at reactors 3 and 4 reactor buildings and used fuel pools was stopped on Monday while TEPCO assessed the effectiveness of these efforts.

Workers were evacuated from the area around reactors 2 and 3 Monday when smoke was observed coming from the secondary containment buildings.

Electricity is expected to be restored to both reactors 3 and 4 by March 23.

Radiation dose rates at monitoring posts are slightly higher than on past days. Rates at the plant site boundary range from 1 to 3 millirem per hour. Radiation dose rates in the area where fire trucks have been located are reported to be 2 to 3 rem per hour, with some isolated areas as high as 30 rem per hour.

Fukushima Daini

All reactors are in cold shutdown and are stable.

MINISTRY OF EDUCATION, CULTURE, SPORTS, SCIENCE AND TECHNOLOGY-JAPAN March 20, 2011, 12:00 GMT                                      Click here for readings of environmental radioactivity levels by Japanese city.

JAPAN ATOMIC INDUSTRIAL FORUM March 20, 2011, 12:00 GMT  Information regarding the status of Fukushima #1 power station, from news reports aired by NHK .

  • The self-defense force conducted the operation of spraying water to the spent fuel pool at unit-4 two times today. Total amount of water sprayed is 160n ton.

  • Work to recover external AC power is in progress at unit-1 and 2. External AC power cable has already been connected to the distribution switchboards of Unit- 1 and unit-2. AC power will be provided to these units after current inspection to check problem. TEPCO wants to distribute AC power to the main control room first so that they can figure out the status of reactor, which is useful information in taking measures.

NUCLEAR ENERGY INSTITUTE March 19, 24:00 GMT                   Powered by an emergency diesel generator, pumps are circulating cooling water in the spent fuel pools of reactors 5 and 6 at the Fukushima Daiichi nuclear power plant, according to reports. Tokyo Electric Power Company also added water to the used fuel pool at reactor 3 after elite firefighters from Tokyo spent 13 hours operating a high-pressure spray truck that pumped seawater into the pool.

The company and response workers were planning to spray water into the used fuel pool at reactor 4 on Sunday.

Electric power lines are connected to reactors 1 and 2, and engineers expected to bring power to the remaining reactors on Sunday, according to the Japan Atomic Industrial Forum. "We do not know if the water pumps [at Fukushima Daiichi] have been damaged and if they will work when power is restored," the International Atomic Energy Agency said.

Tokyo Electric Power Co. reported that holes have been drilled into the ceilings of the buildings that house reactors 5 and 6 to prevent the buildup of hydrogen in the buildings.

Fukushima Daini

All four reactors at Fukushima Daini nuclear power plant have reached cold shutdown conditions with normal cooling

THE NUCLEAR COMMUNICATIONS NETWORK March 19, 2011 (posted on ANS Nuclear Cafe at 17:15 GMT) Radiation In Food 'No Immediate Threat' Says Japan (NucNet): The government's chief cabinet secretary Yukio Edano said in a statement today (Saturday) that radiation exceeding the government-set radiation level was detected in sampled milk in Fukushima Prefecture and insix samples of spinach in neighbouring Ibaraki Prefecture.

He said the radiation measured from the samples poses "no immediate threat" to health. Even if a person was exposed to it for a year, the amount of radioactive substances detected in the milk would result in a radiation dose equivalent to the dose a patient would receive from one CT scan. The radiation detected from the spinach is equivalent to one-fifth of a single CT scan.

The International Atomic Energy Agency (IAEA) said the Japanese Ministry of Health, Labour and Welfare has confirmed the presence of radioactive iodinecontamination in food products measured in Fukushima Prefecture.

The IAEA also confirmed that evacuees leaving the 20-kilometre area around the plant have been advised to take stable iodine, which can help prevent the accumulation of radioactive iodine in the thyroid. Stable iodine pills and syrup (for children) have been made available at evacuation centres.

The IAEA said the ministry has stopped the sale of all food products from Fukushima Prefecture.

According to the latest data, the food products were measured from 16-18 March. No other radioactive isotopes have been shown to increase in the analysis of food products around Fukushima.

Though radioactive iodine has a short half-life of about eight days and decays naturally within a matter of weeks, there is a short-term risk to human health if radioactive iodine in food is absorbed into the human body.

If ingested, it can accumulate in and cause damage to the thyroid. Children and young people are particularly at risk of thyroid damage.

Monitoring of the dose rates in the environment outside the 20-kilometre evacuation zone by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) showed slowly decreasing values on Saturday afternoon incomparison with the two previous days.

Fukushima-Daiichi Status

The immediate threat at Fukushima-Daiichi nuclear plant remains the possibility of damage to spent fuel in the spent fuel pools at all six reactor units, the Japan Atomic Industrial Forum (JAIF) said.

At unit 3, efforts to fill the spent fuel pool with water began at 14:00 Japan time (06:00 central European time) on 19 March using police high-pressure water cannon and Japanese Self-Defence Force fire engines. US Army fire engines were also used, according to JAIF.

These efforts had been continuing for seven hours at the time of the last update issued by JAIF. Workers were preparing to fill the spent fuel pool at unit 4, JAIF said.

Efforts are under way to restore an external power supply to the plant. JAIF said the supply was scheduled be connected to units 1 and 2 today (19 March Japan time). Units 3 to 6 are scheduled to be connected on 20 March.

The IAEA said it was not known if the water pumps have been damaged and if they will work when power is restored.

Fuel Integrity in Spent Fuel Pools

Unit 1: Water injection is being considered.

Unit 2: No information.

Unit 3: Water level low, water injection continues.

Unit 4: Water level low, preparing water injection.

Unit 5: Pool temperature high, but decreasing.

Unit 6: Pool temperature increasing.

Common spent fuel pool: secure water level and a slow rise in temperature, according to Tepco.

The IAEA said it lacked reliable, validated data on water levels and temperatures at the spent fuel pools at units 3 and 4. The agency said temperatures at the spent fuel pools in units 5 and 6 had risen in the past few days, but this does not give rise to immediate concern. Water continues to be circulated within the reactor pressure vessels and the spent fuel ponds at both units.

Reactor Status

Units 1, 2 and 3: Injecting seawater continues. Core and fuel integrity damaged, reactor pressure vessel integrity "unknown".

Unit 4: Already shut down when the quake struck. Building integrity severely damaged.

Unit 5: Already shut down when the quake struck. Sufficient level of reactor coolant to ensure safety is maintained and operation of one of the diesel generators has been re-established. Venting not necessary.

Unit 6: Already shut down when the quake struck. Sufficient level of reactor coolant to ensure safety is maintained and operation of a second diesel generator has been re-established. Venting not necessary.

TOKYO ELECTRIC POWER COMPANY March 19, 2011, 15:00 GMT

No New Developments since 9:00pm, 19th March
Unit   Status
1    • Reactor cold shutdown, stable water level, offsite power is
       available.
     • No cooling water is leaked to the reactor containment vessel.
     • Maintain average water temperature at 100°C in the pressure
       restraint.
2    • Reactor cold shutdown, stable water level, offsite power is
       available.
     • No cooling water is leaked to the reactor containment vessel.
     • Maintain average water temperature at 100°C in the pressure
       restraint.
3    • Reactor cold shutdown, stable water level, offsite power is
       available.
     • No cooling water is leaked to the reactor containment vessel.
     • Maintain average water temperature at 100°C in the pressure
       restraint.
4    • Reactor cold shutdown, stable water level, offsite power is
       available.
     • No cooling water is leaked to the reactor containment vessel.
     • Maintain average water temperature at 100°C in the pressure
       restraint.
other• In the Unit 1, 2, 3 and 4, which automatically shut down due
       to the Tohoku-Chihou-Taiheiyo-Oki Earthquake on March 11th, 2011,
       we had been preparing measures for decreasing the pressure of each
       reactor containment vessel since March 12th. However, on March
       17th, we released such preparation in all of the Units.

NUCLEAR ENERGY INSTITUTE March 19, 2011, 14:00 GMT                         At a March 19 news conference, Japan's Chief Cabinet Secretary Yukio Edano said that sea water injection is continuing at reactors 1, 2 and 3 at the Fukushima Daiichi nuclear power plant.

Preparations were being made to spray water into the used fuel pool at reactor 4, and an unmanned vehicle sprayed more than 1,500 gallons of water over seven hours into the used fuel pool at reactor 3, Edano said. He also said he believed that the situation at the reactor 3 fuel pool is stabilizing.

Some reactor cooling capacity has been restored at reactors 5 and 6 after the installation of generators at those reactors, Edano added.

Edano said that progress had been made on "a fundamental solution" to restore power at the Fukushima Daiichi nuclear power plant, with electricity expected to be restored at reactors 1 and 2 today and reactor 3 as early as Sunday.

Edano said that additional equipment was being transported to the site and that other means of providing cooling water to the pool is be examined.

Radiation dose at the west gate of the Fukushima Daiichi was 83 millirem per hour on March 18 at 7:10 p.m. EDT and dropped to 36 millirem per hour by 8 p.m. EDT, Edano said. Radiation levels have decreased since March 16. Although they are higher than normal, radiation levels near the reactors are within the range that allows workers to continue onsite recovery measures, the International Atomic Energy Agency said.

According to the IAEA, radiation dose rates in Tokyo and other areas outside the 30-kilometer zone remain far below levels which would require any protective action by the public.

All reactors at the Fukushima Daini nuclear power plant are in cold shutdown (See the Japan Atomic Industrial Forum website).

Radiation levels have increased above the federal government's level in some food products from the Fukushima Prefecture and nearby areas. These levels were detected in samples of milk in Fukushima Prefecture and six samples of spinach in neighboring Ibaraki Prefecture, according to the Japan Atomic Industrial Forum. Edano said that if these products are consumed for a year, the total radiation dose would be equivalent to one CT scan.

Additional monitoring of food products is continuing in those regions.

JAPAN ATOMIC INDUSTRIAL FORUM March 19, 2011, 13:00 GMT         Click here for status of Fukushima Daiichi nuclear power plants.

NUCLEAR ENERGY INSTITUTE March 18, 2011, 21:30 GMT

NEI has uploaded a new video to it YouTube channel. It features Jeff Foster, Constellation Energy's director of radiation protection, putting the low radiation levels detected on the west coast into context.

REUTERS March 18, 2011 20:08 GMT                                          Radiation fears may be greatly exaggerated As workers struggle to contain the fallout from the crippled nuclear plant in northeastern Japan, people as far away as Illinois are calling public health officials in a state of panic.

They are hoping to get their hands on potassium iodide pills to protect them from radiation -- despite warnings that, in the absence of a real nuclear threat, taking the medicine is riskier than doing nothing.

Sixty-six years after the first atomic bomb exploded over the city of Hiroshima, radiation spooks people everywhere. But the anxiety is largely disproportionate to the actual danger.

"People in general have an exaggerated fear of radiation. That is true in the United States, and it is probably even more so in Japan," said Jerrold Bushberg, director of health physics programs and clinical professor of radiology and radiation oncology at the University of California Davis.

Despite the Japanese government's assurances that the risk so far is minimal, residents of Tokyo have flooded out of the city and foreigners have fled the country, hoping to escape a threat they cannot see.

The fact is that everyone is exposed to small amounts of radiation every day just from living on earth or flying in an airplane. That all adds up to about 2.4 units, known as millisieverts, a year. This can vary widely, ranging from 1 to 10 millisieverts, depending on where you live.

Background radiation will cause 1 out of 100 people to die of cancer in their lifetimes, said Dr. Donald Bucklin, who spent 10 years as medical director for the Palo Verde nuclear plant in Arizona, the largest nuclear plant in the United States. Additional exposure increases this risk.

In Tokyo, 150 miles from the Fukushima Daiichi plant, people grew fearful when readings rose about 10 times above the normal reading. At that level, residents were exposed to 0.809 microsieverts per hour -- 1,000 times less than a millisievert, or about 10 times less than a chest X-ray.

"The levels of radiation experienced by the public at present should be no cause for concern," said Dr. Richard Wakeford, visiting professor of epidemiology at the Dalton Nuclear Institute at University of Manchester in Britain.

"To put radiation doses into context, many Japanese undergo CT scans for cancer screening purposes, and these scans produce radiation doses of about 10 millisieverts (10,000 microsieverts) -- much more than they are receiving from the Fukushima reactors."

ABC NEWS March 18, 2011, 16:30 GMT

Satellite images before/after, superimposed and interactive. Includes shots of Fukushima Daiichi nuclear plant.

THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update / Brief No 72 / 18 March 2011 (posted on ANS Nuclear Cafe at 16:30 GMT)

Radiation Levels Above Normal, But Falling, Say Authorities

(NucNet): Radiation levels on the site and at the site boundary of

the Fukushima-Daiichi nuclear power plant in Japan are slowly falling, but

are still far above normal levels, according to figures from Tokyo Electric

Power Company (Tepco) and Japan's Nuclear and Industrial Safety Agency

(NISA).

At a monitoring post near one of the gates, readings have fallen from 310

microsieverts per hour (microSv/hr) yesterday to 264 microSv/hr (at 12:00

Japan time on 18 March), they said.

Readings from a mobile monitoring post on the plant site have not been

updated today, but final readings from yesterday (17 March) at 20:00 Japan

time showed 3,600 microSv/hr.

In most countries, the natural background radiation level is in the range of

0.2 to 0.5 microSv/hr, including the natural radon background radiation in

buildings.

Unit Status: 18 March 06:00 Japan Time

Unit 1: Cooling with seawater continues.

Unit 2: Cooling with seawater continues. White smoke has been discharged

from the reactor building, where damage is suspected to the containment

vessel. The cause of the smoke has not been confirmed.

Unit 3: Cooling with seawater continues. After dropping water four times

from helicopters yesterday, five tanks of water have been injected from the

ground to the spent fuel pool sector using a water-cannon truck. The results

are being evaluated.

Unit 4: Work continues to stabilise the reactor, which was shut down at the

time of the earthquake and has no fuel in it. Work also continues to

stabilise the spent fuel pool, which is almost full of spent fuel. The plan

is to fill this pool with cooling water from water cannon and from the

unit's normal pumps as soon as power is re-established onsite. The

International Atomic Energy Agency (IAEA) said the temperature of the spent

fuel at unit 4 was 84 degrees Celsius on 14 March at 04:08 Japan time.

There are no newer readings.

Units 5 and 6: The status of these reactors and of their fuel pools remains

stable as long as the emergency power diesel engine for unit 6 - the only

one that is working - remains operational and supplies power to the pool

cooling system and essential water cooling components. Tepco said it hopes

the situation can be improved with restoration of the plant's main external

power supply. The IAEA said the temperature of the fuel in the unit 5 fuel

pool was 65.5 degrees Celsius at 03:00 Japan time on 18 March.

At unit 6 it was 62 degrees Celsius.

External power supply: A connection has been laid from the Tohoku

high-voltage line to the site and at 06:30 Japan time today it was being

checked. Final connection must wait until water injection can be

interrupted. The IAEA said engineers had also begun to lay an external grid

power line cable to unit 2 at the plant. The operation was continuing as of

05:30 Japan time. They plan to reconnect power to unit 2 once the spraying

of water on the unit 3 reactor building is completed.

The latest status update from the Japan Atomic Industrial Forum is

online.

NUCLEAR ENERGY INSTITUTE March 18, 2011 15:30  GMT

Reactors 1, 2 and 3 at the Fukushima Daiichi nuclear power plant are in stable condition, with workers continuing to provide seawater cooling into the reactors. Containment integrity is believed to be intact on reactors 1, 2 and 3, and containment building pressures are elevated but are within design limits.

Site radiation doses have been decreasing since March 16. Radiation dose rates are fluctuating based on some of the relief operations, such as adding cooling water to the used fuel pools. Recent readings at the plant boundary are about 2 millirem per hour. Radiation dose rates at reactor 3 range between 2,500 and 5,000 millirem per hour.

The Japanese Self-Defense Force restarted cooling water spray into the Unit 3 reactor building and spent fuel pool at around 1 a.m. EDT on March 18. Plans are to spray 50 tons of water on the reactor 3 reactor building/spent fuel pool using seven fire-fighting trucks.

A diesel generator is supplying power to reactors 5 and 6. TEPCO is installing high voltage cables from a nearby transmission line to reactors 1 and 2. Once electricity supply is re-established, priority will be given to restoring power to reactor heat removal systems and cooling water pumps. Workers are seeking to install electrical cables to reactors 3 and 4 components in about two days.

Fukushima Daini

All four reactors at Fukushima Daini remain shut down with normal cooling being maintained using residual heat removal systems.

Daiichi Accident Rated 5 on International Event Scale

New International Nuclear and Radiological Event Scale (INES) ratings have been issued for the accident at the Fukushima Daiichi and Daini nuclear power plants, the International Atomic Energy Agency said.

Reactor core damage at the Daiichi reactors 2 and 3 caused by a loss of cooling function has resulted in a rating of 5 on the seven-point scale.

The loss of cooling and water supply functions in the spent fuel pool of reactor 4 was rated a 3, or "serious" incident. The loss of cooling functions in the reactors 1, 2 and 4 of the Fukushima Daini nuclear power plant has led to a rating of 3.

The rating for the Chernobyl accident was 7, or a "major accident" on the INES scale. The Three Mile Island accident was 5, or an "accident with wider consequences." For more information on INES, see the IAEA's website and this IAEA leaflet.

NEI has updated its online fact sheet, Perspective on Radiation Releases and Emergency Planning at U.S. Nuclear Power Plants.

NEW YORK TIMES March 18, 2011 15:30 GMT                                                   Repairs Go On at Plant as Japan Raises Severity of Crisis Japanese engineers battled on Friday to cool spent fuel rods and restore electric power to pumps at the stricken Fukushima Daiichi Nuclear Power Station as new challenges seemed to accumulate by the hour, with steam billowing from one reactor and damage at another apparently making it difficult to lower temperatures.

As the crisis seemed to deepen, Japan's nuclear safety agency raised the assessment of its severity to 5 from 4 on a 7-level international scale. Level 4 is for incidents with local consequences while level 5 - the rating used for crisis at Three Mile Island in 1979 - denotes broader consequences.

It was not immediately clear why the action had been taken now, nor why it took Japan so long to do so. American officials warned earlier this week that the situation at the crippled plant was much more serious than Japanese officials had indicated, whether because they were truly less worried or playing down the scope of the problems for fear of sparking panic.

The Chernobyl disaster in 1986, the world's worst nuclear calamity, was rated a 7.

In a further sign of spreading alarm that uranium in the Japanese plant could begin to melt, Japan planned to import about 150 tons of boron from South Korea and France to mix with water to be sprayed onto damaged reactors, French and South Korean officials said Friday. Boron absorbs neutrons during a nuclear reaction and can be used in an effort to stop a meltdown if the zirconium cladding on uranium fuel rods is compromised.

Click here for full NYT article.

AMERICAN NUCLEAR SOCIETY March 18, 2011, 15:30 GMT                   ANS members offer expertise to the media on nuclear-related developments in Japan. Click here for list of ANS members who've been in the media.

JAPAN ATOMIC INDUSTRIAL FORUM March 18, 2011                           15:00 GMT                                                                                                                                    Click here for sequence of developments at nuclear power plants affected by earthquake

FOX NEWS March 18, 2011, 15:00 GMT                                                                      Poll: Despite Shock at Crisis in Japan, Half in U.S. Call Nuclear Energy Safe

Americans are shocked by the devastation in Japan after a massive earthquake and tsunami spawned a nuclear crisis, but about half of American voters still say they think nuclear power is a safe source of energy, according to a Fox News poll released Thursday. Click here for poll results.

For complete story, click here.

TOKYO ELECTRIC POWER COMPANY March 18,2011, 05:00 GMT

Plant Status of Fukushima Daiichi Nuclear Power Station

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.

  • Unit 1 (shut down)

  • Reactor has been shut down. However, the explosive sound and white smoke were confirmed after the big quake occurred at 3:36PM Mar 12th. It was assumed to be hydrogen explosion.

  • TEPCO has been injecting sea water into the reactor pressure vessel.

  • Unit 2 (shut down)

  • Reactor has been shut down and the level of reactor coolant had dropped and the reactor pressure had increased because the Reactor Core Isolation Cooling System stopped. Measures were taken to lower the pressure within the Reactor Containment Vessel and to inject sea water into the Reactor while carefully confirming safety. The level of reactor coolant and the pressure of the Reactor resumed.

  • At approximately 6:00AM on March 15, 2011, an abnormal noise began emanating from nearby Pressure Suppression Chamber and the pressure within this chamber decreased.

  • TEPCP has been injecting sea water into the reactor pressure vessel.

  • Unit 3 (shut down)

  • Reactor has been shut down. However, the explosive sound and white smoke were confirmed at 11:01AM Mar 14th. It was assumed to be hydrogen explosion.

  • At 8:30AM on March 16th, fog like steam was confirmed arising from the reactor building.

  • At approximately 6:15AM on March 17th the pressure of the Suppression Chamber has temporarily increased.

  • TEPCO has been injecting sea water into the reactor pressure vessel.

  • Unit 4 (outage due to regular inspection)

  • Reactor has been shut down. However, at approximately 6AM on March 15th.

  • We have confirmed the explosive sound and the sustained damage around the 5th floor rooftop area of the Nuclear Reactor Building.

  • On March 15th and 16th, we respectively confirmed the outbreak of fire at the 4th floor of the northwestern part of the Nuclear Reactor Building. TEPCO immediately reported this matter to the fire department and the related authorities. TEPCO employees confirmed that each fire had already died down by itself.

  • At this moment, TEPCO does not consider any reactor coolant leakage inside the reactor containment vessel happened.

  • Unit 5 (outage due to regular inspection)

  • Reactor has been shut down and the sufficient level of reactor coolant to ensure safety is maintained.

  • At this moment, we do not consider any reactor coolant leakage inside the reactor containment vessel happened.

  • Unit 6 (outage due to regular inspection)

  • Reactor has been shut down and the sufficient level of reactor coolant to ensure safety is maintained.

  • At this moment, we do not consider any reactor coolant leakage inside the reactor containment vessel happened.

  • Cooling of spent fuel pools

  • In Unit 3, water discharge by Self-Defense Force's helicopters was conducted from 9:48 AM in the morning on March 17th. Also water discharge by the riot police's high-pressure water cannon trucks and Self-Defense Force's fire engines was conducted from approximately 7PM on March 17th and finished at 8:09PM.

  • In Unit 3, water discharge by Self-Defense Force's fire engines was conducted from approximately 2 PM

  • TEPCO is considering further water discharge at Unit 3 and others subject to the conditions of spent fuel pools.

Further information from TEPCO is available here.

JAPAN ATOMIC INDUSTRIAL FORUM March 18, 2011                           01:56 GMT                                                                                                                                   Status of Fukushima #1 power station

The Chief Cabinet Secretary reported at press briefing this morning:

  • Operation for filling the spent fuel pool with water at Unit-3 was conducted yesterday. It seems that water reached the pool. However, how much is unknown. Same operation will be conducted today.

  • Operation for filling the spent fuel pool with water from the ground will be conducted at unit-1 also, if it doesn't affect the operation for unit-3.

  • Operation for installing cables and distribution system to the power plant to provide AC power from the grid is going on.

  • Radiation monitors located around the station is detecting radiation. Although radiation is relatively high in some area, it doesn't reach the harmful level to human in general. Even in the hot spots, radiation doesn't reach the level at which radiation has an immediate affect on human body.

NUCLEAR ENERGY INSTITUTE March 17, 2011, 21:00 GMT

It is unlikely that radiation released from the nuclear reactors in Japan will harm anyone in the United States, President Obama said in a press briefing this afternoon.

"We do not expect harmful levels of radiation to reach the United States, Hawaii, Alaska or U.S. territories in the Pacific," Obama said. He added that the Centers for Disease Control and Prevention "does not recommend that people in the U.S. take precautionary measures other than staying informed."

Obama said "our nuclear plants have undergone exhaustive study and have been declared safe for any number of contingencies." However, he said that when there is an event such as the Fukushima accident, "we should learn from that. That's why I have asked the NRC to do a comprehensive review of our nuclear plants" in light of the natural disaster that has happened in Japan.

In a briefing earlier on Thursday, Gregory Jaczko, chairman of the U.S. Nuclear Regulatory Commission, said, "There can't be any harm to anyone in the United States" from the Japanese nuclear power plant.

Dan Poneman, the deputy secretary of energy, said today that two U.S. flights to Japan collected information on radiation levels. These readings informed the decision to recommend that Americans evacuate an area 50 miles from the Fukushima Daiichi nuclear energy facility.

Poneman expressed confidence in the safety of U.S. nuclear power plants, saying they're evaluated on a "minute by minute" basis. Taking safety precautions "goes back decades," he said. Tough safety standards have been in effect and upgraded since 1979, he said.

Status of Fukushima plants

In Japan, engineers have laid a power line that can connect reactor 2 of the Daiichi facility to the off-site power grid, the International Atomic Energy Agency reported. Workers are working to reconnect the power to reactor 2 after they complete spraying water into the reactor 3 complex to provide additional cooling to the used fuel pool. Reconnecting to the power grid is expected to enhance efforts to prevent further damage at the plant.

Japan's Nuclear and Industrial Safety Agency reported on Thursday that the backup diesel generator for reactor 6 is working and supplying electricity to reactors 5 and 6. TEPCO is preparing to add water to the storage pools that house used nuclear fuel rods at those two reactors

NUCLEAR COMMUNICATIONS NETWORK March 17, 2011, 21:00 GMT

Japan Releases Radiation Data From More Than 50 Monitoring Posts A Japanese government ministry has released radiation data

from more than 50 monitoring posts (MPs) around the Fukushima-Daiichi

nuclear power plant in Japan that show transient high readings of up to 80

microsieverts per hour (microSv/hr) at two locations more than 20 kilometres

from the plant.

The data, released today by the Ministry of Education, Culture, Sports,

Science & Technology (MEXT), show the 80 microSv/hr readings at MP number 4, about 35 km northwest of the site, and MP number 21, about 30 km northwest of the site.

The MEXT table with radiation readings is online

The first reading was taken at 11:30 yesterday (Wednesday) Japan time (03:20

central European time) and the second at 11:35 Japan time.

MEXT also released a map which shows radiation readings within the 20km - 30 km evacuation zone ranged from 2.1 to 40 microSv/hr. These readings were taken today between 09:20 and 17:43 Japan time.

Just outside the 30 km zone and to the west of the plant, today's peak

reading was 170 microSv/hr. Other readings outside the 30 km zone to the

west of the plant ranged from 0.7 microSv/hr to 20 microSv/hr.

In most countries, the natural background radiation level is in the range of

0.2 to 0.5 microSv/hr, including the natural radon background radiation in

buildings.

Many of the latest readings were taken during a period while venting was

being carried out at the plant and when a fire broke out in unit 4, which

resulted in peak readings caused by masses of contaminated air moving inland

on a generally easterly wind.

At Fukushima-Daiichi's main gate on 16 March readings varied from 8,000

microsieverts per hour (microSv/hr) early in the night down to 580

microSv/hr at around 09:30 Japan time. At 12:30 they increased to a peak

value of 10,850 microSv/hr and since then have been falling steadily to

about 350 microSv/hr late evening on 16 March Japan time.

Readings today (17 March) varied between about 350 microSv/hr at midnight

and 310 microSv/hr at 15:30. These values do not represent too serious a

problem for people working on the site.

Earlier today, Japanese authorities started using helicopters to drop water

onto the spent fuel pools at Fukushima-Daiichi units 3 and 4 in an effort to

counter what they called the "immediate threat" of damage to the fuel, the

Japan Atomic Industrial Forum (JAIF) said.

In an update at 08:00 CET, JAIF said the helicopter operation had begun at

01:48 CET on 17 March.

The Nuclear and Industrial Safety Authority (NISA) said workers at the plant

started to cool the unit 3 and 4 spent fuel pools using high pressure ground

pumps at 08:10 CET .

NISA also said the temperature of fuel in the spent fuels pools at units 5

and 6 had reached about 65 degrees Celsius and 84 degrees Celsius at unit 4

this afternoon. According to JAIF spent fuel rods in unit 4's fuel pool had

probably been damaged.

There was no information on the condition of spent fuel in the spent fuel

CNN March 17, 2011, 17:15 GMT. CNN has a "Japan's nuclear concerns explained" interactive presentation on its website. It includes photos, videos, and explanations of events, and a primer on reactor basics.

BBC News March 17, 2011, 16:52 GMT  Japan steps up cool efforts Helicopters dumped tonnes of seawater to try to prevent fuel rods melting, and water cannon joined in the operation on the ground.

The International Atomic Energy Agency says the situation remains serious but has not significantly worsened.

The confirmed death toll from Friday's 9.0 magnitude quake, which triggered the tsunami, has risen above 5,400.

Police say about 9,500 people are still missing.

At a press conference, IAEA official Graham Andrew said reactor 4, which was inactive but being used to store spent fuel rods, was still a "major safety concern".

He said water levels were also falling in the cooling pools of reactors 5 and 6.

But he said there had been no rise in radiation in Tokyo and that levels remained far below those dangerous to human health.

Despite assurances, the streets of the capital - including its popular Ginza retail district - remain unusually empty, with many people continuing to stay at home or leaving the capital.

Japan's military CH-47 Chinook helicopters began spraying tonnes of seawater on reactors 3 and 4 at Fukushima, 220km (140 miles) from Tokyo, at 0948 local time (0048 GMT), officials said.

Click here for full BBC News story.

NUCLEARSTREET.COM March 17, 2011 16:16 GMT                                               A Japanese TV station has obtained this video of the damaged Fukushima Daiichi nuclear plant taken from a nearby helicopter. It shows the extensive damage to the units.

Click here for video of damaged Fukushima Daiichi plant.

NEW YORK TIMES March 17, 2011, 16:00 GMT Danger of Spent Fuel Outweighs Reactor Threat

Years of procrastination in deciding on long-term disposal of highly radioactive fuel rods from nuclear reactors are now coming back to haunt Japanese authorities as they try to control fires and explosions at the stricken Fukushima Daiichi Nuclear Power Station.

Some countries have tried to limit the number of spent fuel rods that accumulate at nuclear power plants - Germany stores them in costly casks, for example, while Chinese nuclear reactors send them to a desert storage compound in western China's Gansu province. But Japan, like the United States, has kept ever larger numbers of spent fuel rods in temporary storage pools at the power plants, where they can be guarded with the same security provided for the power plant.

Figures provided by Tokyo Electric Power on Thursday show that most of the dangerous uranium at the power plant is actually in the spent fuel rods, not the reactor cores themselves. The electric utility said that a total of 11,195 spent fuel rod assemblies were stored at the site.

That is in addition to 400 to 600 fuel rod assemblies that had been in active service in each of the three troubled reactors. In other words, the vast majority of the fuel assemblies at the troubled reactors are in the storage pools, not the reactors.

Now those temporary pools are proving the power plant's Achilles heel, as the water in the pools either boils away or leaks out of their containments, and efforts to add more water have gone awry. While spent fuel rods generate significantly less heat than newer ones, there are strong indications that the fuel rods have begun to melt and release extremely high levels of radiation. Japanese authorities struggled Thursday to add more water to the storage pool at reactor No. 3.

Four helicopters dropped water, only to have it scattered by strong breezes. Water cannons mounted on police trucks-equipment designed to disperse rioters-were deployed in an effort to spray water on the pools. It is unclear if they managed to achieve that.

Nuclear engineers around the world have been expressing surprise this week that the storage pools have become such a problem. "I'm amazed that they couldn't keep the water in the pools," said Robert Albrecht, a longtime nuclear engineer who worked as a consultant to the Japanese nuclear reactor manufacturing industry in the 1980s and visited the Fukushima Daiichi reactor then.

Very high levels of radiation above the storage pools suggest that the water has drained in the 39-foot-deep pools to the point that the 13-foot-high fuel rod assemblies have been exposed to air for hours and are starting to melt, he said. Spent fuel rod assemblies emit less heat than fresh fuel rod assemblies inside reactor cores, but the spent assemblies still emit enough heat and radioactivity that they must still be kept covered with 26 feet of water that is circulated to prevent it from growing too warm.

Gregory Jaczko, the chairman of the United States Nuclear Regulatory Commission, made the startling assertion on Wednesday that there was little or no water left in the storage pool located on top of reactor No. 4, and expressed grave concern about the radioactivity that would be released as a result. The spent fuel rod assemblies there include 548 assemblies that were only removed from the reactor in November and December to prepare the reactor for maintenance, and may be emitting more heat than the older assemblies in other storage pools.

Even without recirculating water, it should take many days for the water in a storage pool to evaporate, nuclear engineers said. So the rapid evaporation and even boiling of water in the storage pools now is a mystery, raising the question of whether the pools may also be leaking.

The full New York Times story is available here.

NUCLEAR ENERGY INSTITUTE March 17, 2011, 15:35 GMT

Fukushima Daiichi

The reactors at the Fukushima Daiichi plant are in stable condition and are being cooled with seawater, but workers at the plant continue efforts to add cooling water to fuel pools at reactors 3 and 4.

The status of the reactors at the site is as follows:

  • Reactor 1's primary containment is believed to be intact and the reactor is in a stable condition. Seawater injection into the reactor is continuing.

  • Reactor 2 is in stable condition with seawater injection continuing. The reactor's primary containment may not have been breached, Tokyo Electric Power Co. and World Association of Nuclear Operators officials said on Thursday.

  • Reactor 3 is in stable condition with seawater injection continuing. The primary containment is believed to be intact. Pressure in the containment has fluctuated due to venting of the reactor containment structure.

Access problems at the site have delayed connection of a temporary cable to restore off-site electricity. The connection will provide power to the control rod drive pump, instrumentation, batteries and the control room. Power has not been available at the site since the earthquake on March 11.

TEPCO officials say that although one side of the concrete wall of the fuel pool structure has collapsed, the steel liner of the pool remains intact, based on aerial photos of the reactor taken on March 17. The pool still has water providing some cooling for the fuel; however, helicopters dropped water on the reactor four times during the morning (Japan time) on March 17. Water also was sprayed at reactor 4 using high-pressure water cannons.

Reactors 5 and 6 were both shut down before the quake occurred. Primary and secondary containments are intact at both reactors. Temperature instruments in the spent fuel pools at reactors 5 and 6 are operational, and temperatures are being maintained at about 62 degrees Celsius. TEPCO is continuing efforts to restore power at reactor 5.

Fukushima Daini

All four reactors at the Fukushima Daini plant have reached cold shutdown conditions with normal cooling being maintained using residual heat removal systems.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 17, 2011, 14:15 GMT Update regarding the Tohoku earthquake

Radiation Levels

  • At 9:20AM (JST) on March 17, radiation level at elevation of 1000ft above Fukushima Daiichi Nuclear Power Station: 4,130 micro sievert.

  • At 9:20AM on March 17, radiation level at elevation of 300ft above Fukushima Daiichi Nuclear Power Station: 87,700 micro sievert. At 11:10AM on March 17, radiation level at main gate (approximately 3281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power station: 646.2 micro sievert.

  • At 7:50PM on March 17, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 3,599 micro sievert.

  • For comparison, a human receives 2,400 micro sievert per year from Natural radiation in the form of sunlight, radon, and other sources. One Chest CT scan generates 6900 micro sievert per scan.

  • Fukushima Daiichi Unit 1 reactor

  • Since 10:30AM on March 14, the pressure within the primary containment vessel cannot be measured.

  • At 12:50PM on March 17, pressure inside the reactor core: 0.185MPa.

  • meters below the top of the fuel rods.At 12:50PM on March 17, water level inside the reactor core: 1.

  • Fukushima Daiichi Unit 2 reactor

  • At 12:25PM on March 16, pressure inside the primary containment vessel: 0.40MPaabs.

  • At 12:50PM on March 17, pressure inside the reactor core: -0.027MPa.

  • At 12:50PM on March 17, water level inside the reactor core: 1.8 meters below the top of the fuel rods.

  • Fukushima Daiichi Unit 3 reactor

  • At 12:40PM on March 16, pressure inside the primary containment vessel: 0.23MPaabs.

  • At 6:15AM on March 17, pressure inside the suppression chamber was observed to fluctuate.

  • At 7:00AM on March 17, pressure inside the suppression chamber: 0.22MPa.

  • At 7:05AM on March 17, pressure inside the suppression chamber: 0.44MPa.

  • At 7:10AM on March 17, pressure inside the suppression chamber: 0.26MPa.

  • At 7:15AM on March 17, pressure inside the suppression chamber: 0.52MPa.

  • At 7:20AM on March 17, pressure inside the suppression chamber: 0.13MPa.

  • At 7:25AM on March 17, pressure inside the suppression chamber: 0.57MPa.

  • At 9:48AM on March 17, a Self Defense Forces helicopter made four water drops aimed for the spent fuel pool.

  • At 4:35PM on March 17, pressure inside the reactor core: 0.005MPa.

  • At 4:35PM on March 17, water level inside the reactor core: 1.95 meters below the top of the fuel rods.

  • At 7:05PM on March 17, a police water cannon began to shoot water aimed at the spent fuel pool until 7:22PM.

  • At 7:35PM on March 17, five Self Defense Forces emergency fire vehicles shot water aimed at the spent fuel pool, until 8:09PM.

  • Fukushima Daiichi Unit 5 reactor

  • At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 145 degrees Fahrenheit.

  • Fukushima Daiichi Unit 6 reactor

  • At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 140 degrees Fahrenheit.

JAPAN ATOMIC INDUSTRIAL FORUM Status of Fukushima 1 power station as of 12:30 GMT, March 17, 2011

Operation for filling the pool with water at unit-3

NHK news reported on the operations conducted today for filling the pool with

water at unit-3 as follows:

  • Water level is low at the spent fuel pools of unit-3. Considering possibility of damage to fuel rods in the pool outside the containment vessel, operation for filling the pool with water were conducted three times.

  • 1st operation Japan Self-Defense Forces dropped 4 huge buckets of seawater from helicopters in this morning. Lead plates were installed at the bottom of the helicopters to shield radiation and crew members wore radiation protection suits.

  • 2nd operation The National Police Agency tried to pour water from the ground with pumper truck in the evening. However, they were not able to come close because of high eadiation and water did not reach the pool.

  • 3rd operation Japan Self-Defense Forces poured 30 tons of water from the ground with 5 special pumper trucks from 19:45 to 20:09. Because these trucks are special, they were able to do this operation without getting off the trucks. Effect of this operation is under evaluation.

JAPAN ATOMIC INDUSTRIAL FORUM March 17, 2011 03:00 GMT Click here for updated graphs showing Fukushima Daiichi status

NUCLEAR ENERGY INSTITUTE March 16, 2011, 23:30 GMT

NEI has added a new video to its YouTube page "NEI Offers Support to Japan." Also available is an updated schematic of the reactor design at Fukushima Daiichi.

TOKYO ELECTRIC POWER COMPANY March 16, 2011, 23:00 GM      Plant status of Fukushima Daiichi Nuclear Power Station

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut

down.

Unit 1 (shut down)

  • Reactor has been shut down. However, the explosive sound and white smoke were confirmed after the big quake occurred at 3:36PM (JST) Mar 12th. It was assumed to be hydrogen explosion and currently under the investigation.

  • TEPCO has been injecting sea water into the reactor pressure vessel.

Unit 2 (shut down)

  • Reactor has been shut down and Reactor Core Isolation Cooling System has been injecting water to the reactor. However, reactor pressure has increased because the system stopped, causing reactor water level to drop. Following the instruction by the government and with fully securing safety, measure to lower the pressure level within the reactor containment vessel and injection of sea water were taken, reactor pressure and water level resumed.

  • TEPCO is continuing the injection of sea water into the reactor.

  • At approximately 6:00am, an abnormal noise began emanating from nearby Pressure Suppression Chamber and the pressure within this chamber decreased. While TEPCO continues sea water injection operations, the temporary transfer of TEPCO employees and workers from other companies not directly involved in this work has begun.

Unit 3 (shut down)

  • Reactor has been shut down. However, the explosive sound and white smoke were confirmed at 11:01AM Mar 14th. It was assumed to be hydrogen explosion and currently under the investigation.

  • As fog like steam was confirmed from reactor building at 8:30AM on March 16th, we transferred the workers to safe area. After that, TEPCO decided to discharge water to the upper side of reactor building by helicopters, but could not do that because there was a trouble with implementation of work.

  • TEPCO plans to discharge water in order to cool spent fuel pool after it completes the preparations by confirming the process of discharging, personnel, and a situation of the site.

  • TEPCO continues monitoring as it was reported that the pressure of the Suppression Chamber temporally increased at around 6:15AM on March 17th.

  • TEPCO has been injecting sea water into the reactor pressure vessel.

Unit 4  (shut down due to regular inspection)

  • Reactor has been shut down. However, TEPCO has confirmed the sustained damage around the 5th floor rooftop area of the Nuclear Reactor Building.

  • Afterward, TEPCO confirmed the outbreak of fire at the northwestern part of Nuclear Reactor Building. TEPCO immediately reported this matter to the fire department and the related authorities.

  • However, at approximately 11:00am, when TEPCO employee arrived at the seen to confirm, the fire had already died down. At 5:45AM on March 16, TEPCO confirmed the outbreak of the fire again, but could not confirm it at 6:15AM. TEPCO will continue to monitor the situation carefully.

Unit 5 (outage due to regular inspection)

  • Reactor has been shut down and sufficient level of reactor coolant to ensure safety is maintained.

  • Currently, TEPCO does not believe there is any reactor coolant leakage inside the reactor containment vessel.

Unit 6 (outage due to regular inspection)

  • Reactor has been shut down and sufficient level of reactor coolant to ensure safety is maintained.

  • Currently, we do not believe there is any reactor coolant leakage inside the reactor containment vessel.

Further information from TEPCO is available at its website.

ABC NEWS March 16, 2011, 22:00 GMT Japan disputes Jaczko claims, says condition stable at Unit Four America's top nuclear official told Congress today that the pool cooling spent fuel rods at the crippled Japanese nuclear complex had lost most of its water or all of its water, a potentially catastrophic situation.

The Japanese quickly challenged that statement, but gave few details saying only that the situation at the holding pool was "stable."

Nuclear Regulatory Commission Chairman Gregory Jaczko said that the fuel pool at unit 4 at the the Fukushima Daiichi nuclear power plant had lost massive amounts of water.

"We believe at this point that unit 4 may have lost a significant inventory, if not lost all of its water," Jaczko told a hearing before the House Energy and Commerce Committee. "What we know at unit three, and again our information is limited, what we believe is that there is a crack in the spent fuel pool for unit three as well, which could lead to a loss of water in that pool."

The spent fuel rods are kept in pools of water to prevent them from overheating and ultimately melting down. The outer shell of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area.

Japan's nuclear safety agency and Tokyo Electric Power Co., which operates the complex, deny water is gone from the pool. Utility spokesman Hajime Motojuku told the Associated Press the "condition is stable" at unit 4.

Radiation levels have risen rapidly at the plant and there is a fear that the situation is heading for the worst. If levels continue to rise the doses emergency workers experience near the reactors could be lethal. One U.S. Official told ABC News that "it would be hard to describe how alarming this is right now" and that a suicide mission might not even be enough to avert disaster.

Jaczko recommends that American citizens living within 50 miles of the Fukushima nuclear power plant evacuate the area.

Full story is available here at ABC News website.

NEW YORK TIMES March 16, 2011, 21:00 GMT                                                  U.S. Calls Radiation 'Extremely High' and Urges Deeper Caution in Japan The chairman of the United States Nuclear Regulatory Commission gave a significantly bleaker appraisal of the threat posed by Japan's nuclear crisis than the Japanese government, saying on Wednesday that the damage at one crippled reactor was much more serious than Japanese officials had acknowledged and advising to Americans to evacuate a wider area around the plant than the perimeter established by Japan.

The announcement marked a new and ominous chapter in the five-day long effort by Japanese engineers to bring four side-by-side reactors under control after their cooling systems were knocked out by an earthquake and tsunami last Friday. It also suggested a serious split between Washington and Tokyo, after American officials concluded that the Japanese warnings were insufficient, and that, deliberately or not, they had understated the potential threat of what is taking place inside the nuclear facility.

Gregory Jaczko, the chairman of the commission, said in Congressional testimony that the commission believed that all the water in the spent fuel pool at the No. 4 reactor of the Fukushima Daiichi Nuclear Power Station had boiled dry, leaving fuel rods stored there exposed and bleeding radiation. As a result, he said, "We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures."

If his analysis is accurate and Japanese workers have been unable to keep the spent fuel at that inoperative reactor properly cooled - it needs to remain covered with water at all times - radiation levels could make it difficult not only to fix the problem at reactor No. 4, but to keep workers at the Daiichi complex from servicing any of the other problem reactors at the plant.

Mr. Jaczko (the name is pronounced YAZZ-koe) said radiation levels may make it impossible to continue what he called the "backup backup" cooling functions that have so far helped check the fuel melting at the other reactors. Those efforts consist of using fire hoses to dump water on overheated fuel and then letting the radioactive steam vent into the atmosphere.

For complete story, see the New York Times.

BBC NEWS March 16, 2011, 20:35 GMT                                                                          US officials have concluded that the Japanese warnings have been insufficient, and that, deliberately or not, they have understated the potential threat of what is taking place inside the nuclear facility, according to the New York Times. Gregory Jaczko, the chairman of the US Nuclear Regulatory Commission, earlier said he believed that all the water in the spent fuel pool at reactor 4 had boiled dry, leaving fuel rods stored there exposed. "We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures," he told a Congressional committee.

NUCLEAR ENERGY INSTITUTE March 16, 2011, 20:30 GMT              Japanese authorities have reported concerns today about the condition of the used nuclear fuel pools at Fukushima Daiichi reactor 3 and reactor 4.

Officials also are preparing to spray water into reactor 4 from ground positions and possibly later into reactor 3. Some debris on the ground from the March 14 explosion at reactor 3 may need to be removed before the spraying can begin.

Most plants store used fuel in steel-lined, concrete vaults filled with water, which acts as a natural barrier for radiation from the used fuel. The water also keeps the fuel cool while the radiation decays-or becomes less radioactive. The water itself does not leave the used fuel pool.

Used nuclear fuel at the Fukushima-Daiichi plant is stored in seven pools (one at each reactor and a shared pool) and in a dry container storage facility (containing nine casks.)

The used fuel pools are designed so that the water in the pool cannot drain down as a result of damage to the piping or cooling systems. The pools do not have drains in the sides or the floor of the pool structure. The only way to rapidly drain down the pool is to have structural damage of the walls or the floor.

For more information on used fuel pools, see NEI's new fact sheet, "Used Nuclear Fuel Storage at the Fukushima Daiichi Nuclear Power Plant."

The U.S. government on Wednesday recommended that Americans within 50 miles of the Fukushima Daiichi plant evacuate the area. The Nuclear Regulatory Commission has posted a news release on its website regarding the evacuation recommendation.

The information contained in NRC's recent press release is new and industry is still evaluating the radiation dose calculations since there is little context for the numbers provided in the press release. On the surface, the estimated doses look to be extremely conservative, but NEI said it has no additional information on which to evaluate them.

ASSOCIATED PRESS March 16, 2011, 20:30 GMT

New power line may ease crisis at Japan nuke plant

A nearly completed new power line could restore cooling systems in Japan's tsunami-crippled nuclear power plant, its operator said Thursday, raising some hope of easing the crisis that has threatened a meltdown and already spawned dangerous radiation surges.

The conditions at the plant appeared to worsen, with white smoke pouring from the complex and a surge in radiation levels forcing workers to retreat for hours Wednesday from their struggle to cool the overheating reactors.

As international concern mounted, the chief of the U.N. nuclear agency said he would go to Japan to assess what he called a "serious" situation and urged Tokyo to provide better information to his organization.

Tokyo Electric Power Co. spokesman Naoki Tsunoda said the new power line to the Fukushima Dai-ichi plant is almost finished and that officials plan to try it "as soon as possible," but he could not say exactly when.

The new line would revive electric-powered pumps, allowing the company to maintain a steady water supply to troubled reactors and spent fuel storage ponds, keeping them cool. The company is also trying to repair its existing disabled power line.

Wednesday's pullback by workers who have been pumping seawater into the reactors cost valuable time in the fight to prevent a nuclear meltdown, a nightmare scenario following Friday's horrific earthquake and tsunami. The disasters pulverized Japan's northeastern coast and are feared to have killed more than 10,000 people.

The tsunami destroyed the complex's backup power system and left operators unable to properly cool nuclear fuel. The 180 emergency workers have been working in shifts to manually pump seawater into the reactors.

Japan's emperor, in an unprecedented made-for-TV speech, called on the country to work together.

NEW YORK TIMES March 16, posted by ANS Nuclear Cafe at 19:00 GMT Radiation at Fukushima Daiichi (for graph, click here)

Radiation jumped significantly from the Fukushima Daiichi nuclear plant on Tuesday during a fire near reactor No. 4, but dropped quickly after the fire was extinguished.

New York Times radiation graph is here.

BLOOMBERG March 16, 2011, 17:40 GMT UN calls emergency meeting as nuclear crisis deepens The United Nations' nuclear agency will call an emergency meeting to discuss the crisis in Japan as a breach at the stricken Fukushima Dai-Ichi plant increased the risk of a radioactive leak.

IAEA Chief Yukiya Amano is flying to Tokyo to talk with authorities today and will return for the meeting as soon as possible, he told reporters in Vienna yesterday. It will be the first extraordinary meeting of the agency's 35-member board since his election to succeed Mohamed ElBaradei two years ago.

The containment vessel of Dai-Ichi's No. 2 reactor may have been breached yesterday, and pressure in the chamber fell "substantially," said Masahisa Otsuku, a Tokyo Electric Power Co. nuclear maintenance official.

The company suspected damage following an explosion in the reactor building March 15. About 70 percent of the fuel rods at the plant's No. 1 reactor and a third of the No. 2 reactor's fuel may have been damaged, and temperatures at spent-fuel-rod- cooling pools were rising, Tepco said.

Clouds of steam rose from the reactor buildings following a fire at Dai-Ichi's No. 4 reactor yesterday morning. Radiation levels at the No. 4 reactor hampered efforts to confirm whether the fire had been extinguished, a day after a similar blaze at the same structure.

"If you get enough cold water inside you may stop the generation of steam and then life will get easier," said Robert Kelley, a nuclear engineer based in Vienna. "As long as there is steam coming out it will carry radioactive particles and gases with it."

Spent Fuel Rods

Temperatures in the spent-fuel-rod cooling pools of the shuttered No. 5 and No. 6 reactors were rising to as high as 63 degrees Celsius (145 degrees Fahrenheit) at 2 p.m. yesterday from 60 degrees Celsius at 7 a.m., said Tsuyoshi Makigami, head of nuclear maintenance at Tepco. Water levels at spent fuel pools at the three inactive reactors, Nos. 4, 5 and 6, dropped by about two meters, exposing the fuel rods, Amano said.

Exposed to air, the fuel bundles could chemically react with moisture, catch fire and spread radiation into the atmosphere, said Edwin Lyman, a physicist with the Union of Concerned Scientists, based in Cambridge, Massachusetts.

Contamination

"Spent fuel is pretty hot and so it is stored under water to keep it cool," said Kelley, who worked for 30 years at the U.S. Energy Department. "If the water leaks or boils away, then the fuel is exposed," then after burning, the uranium corrodes and releases cesium, contaminating the area, he said.

A core group of 50 workers remain at the plant to manage the reactors, Tepco said. Those engineers were temporarily evacuated yesterday when dangerous radiation levels were detected, but have now returned, chief government spokesman Yukio Edano said.

Tepco is building a power cable to supply electricity to the plant's cooling systems, spokesman Daisuke Hirose said. The systems were knocked out by the March 11 earthquake and tsunami. The Yomiuri newspaper reported yesterday that if the plan succeeds, the company may be able to stabilize its reactors. Hirose said there is no timetable for completion.

The latest incidents follow a blast at the No. 3 reactor March 14 after a buildup of hydrogen gas, and a similar explosion at the No. 1 reactor on March 12.

About 140,000 people within a radius of 20 to 30 kilometers from the plant were ordered to stay indoors. The magnitude-9 temblor and tsunami have led to what Prime Minister Naoto Kan has called Japan's worst crisis since World War II. More than 450 aftershocks have followed. The death toll reached 3,771 with 7,843 missing as of 2 p.m. yesterday, the National Police Agency said. The number of dead and missing exceeds the more than 6,400 who died in the 1995 Kobe earthquake.

In a national address yesterday, Emperor Akihito expressed his condolences to victims of the earthquake and tsunami, and told the people of Japan not to give up.

Click here for Bloomberg website.

REUTERS March 16, 2011, 17:06 GMT                                                                       Japan scrambles to pull nuclear plant back from brink Japan's nuclear crisis appeared to be spinning out of control on Wednesday after workers withdrew briefly from a stricken power plant because of surging radiation levels and a helicopter failed to drop water on the most troubled reactor.

In a sign of desperation, police will try to cool spent nuclear fuel at one of the facility's reactors with water cannon, normally used to quell riots.

Early in the day, another fire broke out at the earthquake-crippled facility, which has sent low levels of radiation wafting into Tokyo in the past 24 hours, triggering fear in the capital and international alarm.

Japan's government said radiation levels outside the plant's gates were stable but, in a sign of being overwhelmed, appealed to private companies to help deliver supplies to tens of thousands of people evacuated from around the complex.

"People would not be in immediate danger if they went outside with these levels. I want people to understand this," Chief Cabinet Secretary Yukio Edano told a televised news conference, referring to people living outside a 30-km (18-mile) exclusion zone. Some 140,000 people inside the zone have been told to stay indoors.

The European Union's energy chief, Guenther Oettinger, told the European Parliament that the plant was "effectively out of control" after breakdowns in the facility's cooling system.

Workers cleared debris to build a road so fire trucks could reach reactor No. 4 at the Daiichi complex in Fukushima, 240 km (150 miles) north of Tokyo. Flames were no longer visible at the building housing the reactor.

High radiation levels prevented a helicopter from dropping water into the No. 3 reactor to try to cool its fuel rods after an earlier explosion damaged the unit's roof and cooling system.

The plant operator described No. 3-the only reactor at that uses plutonium in its fuel mix-as the "priority." Plutonium, once absorbed in the bloodstream, can linger for years in bone marrow or liver and lead to cancer.

The situation at No. 4 reactor, where the fire broke out, was "not so good," the plant operator added, while water was being poured into reactors No. 5 and 6, indicating the entire six-reactor facility was now at risk of overheating.

"Getting water into the pools of the No.3 and No.4 reactors is a high priority," Hidehiko Nishiyama, a senior official at Japan's Nuclear and Industrial Safety Administration, told a news conference, adding the pool for spent fuel rods at No. 3 was heating up while No.4 remained a concern.

"It could become a serious problem in a few days," he said.

A military helicopter may be used again to try to drop water and troops mobilized to help pump water by land, he said.

Nuclear experts said the solutions being proposed to quell radiation leaks at the complex were last-ditch efforts to stem what could well be remembered as one of the world's worst industrial disasters.

"This is a slow-moving nightmare," said Dr Thomas Neff, a physicist and uranium-industry analyst at the Massachusetts Institute of Technology.

Click here for the Reuters website.

WORLD NUCLEAR NEWS March 16, 2011, 16:50 GMT                                       Problems for units 3 and 4 Chief cabinet secretary Yukio Edano has described problems that occurred on the morning of 16 March with Fukushima Daiichi 3 and 4, as well as plans to pump water into unit 4.

At 8.34am white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted by the evacuation of workers to after rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 0.6-0.8 millisieverts per hour, but at 10am readings rose to 1.0 millisieverts per hour before falling again just before 11am.

Edano said that one possibility being considered was that the unit 3 reactor had suffered a similar failure to that at unit 2 yesterday, where the torus pressure suppression structure is suspected of being damaged. However, there had been no reported blast or loud sound, which had been the case for unit 2. The immediate focus, said Edano, was on monitoring of water levels and checking pumping operations.

Fuel ponds

About 60% of the total used nuclear fuel from all six reactors is kept in a shared facility, while each of the units also has its own storage pool near the top of the reactor building. At unit 4, the reactor itself contains no fuel, this having been removed to the unit's own store over 100 days ago for maintenance work to take place.

There have now been two fires in the upper portion of unit 4's reactor building, thought to follow an explosion early on 15 March which left the building severely damaged the building. The cause of the fires remains unknown due to radiation in the area, and they could in fact be one fire that died down before reigniting. The exact nature of the explosion is also unknown. The Japan Atomic Industry Forum reports that the level of water in unit 4's fuel pond is low and damage to fuel stored there is suspected. Efforts are underway to refill the pool, including an unsuccessful attempt to douse the building with water from a helicopter, hoping to get some to go through the damaged building.

The full article is available here at the World Nuclear News website.

NUCLEAR ENERGY INSTITUTE March 16, 2011, 14:00 GMT

News reports that high radiation levels led to the evacuation of all workers from the Fukushima Daiichi nuclear power station are not accurate. Workers were evacuated for about an hour, but returned to the site to continue efforts to restore safe conditions at the plant.

Restoration of electrical power to the site was under way at the Daiichi plant as of 6:00 a.m. EDT (10:00 GMT) Wednesday. A temporary cable was being connected between an off-site power line and Daiichi reactor 3. Off-site power has not been available at the site since the earthquake on March 11

Reactors 1, 2, and 3 at the plant are being cooled with seawater. There is some level of uranium fuel damage at all three units, and containment structure damage is suspected at reactor 2

Before the earthquake, reactor 4 had been in refueling and was completely defueled. Attempts to provide cooling water to the used fuel pool at reactor 4 by helicopter were not successful. Preparations are being made to inject water into the fuel storage pool using a high-capacity spray pump. There have been two fires inside the reactor containment building at reactor 4, but they have been extinguished. Although the reactor containment building at Unit 4 was damaged, the primary containment vessel remains intact

At the Fukushima Daini site, all four reactors are safely shut down and cooling functions are being maintained

JAPAN ATOMIC INDUSTRIAL FORUM 10:00 GMT, March 16, 2011

New updated status and latest information of Fukushima-1 and Fukushima-2 Nuclear Power Stations are available at JAIF's website.

JAIF will update the chart daily so that readers may be able to get updated information about the nuclear plants in the area affected by the Tohoku massive earthquake.

Another magnitude 6.0 earthquake hit Shizuoka Prefecture at 10:31 p.m. on March 16 (Japan Time, 13:31 GMT). There is no affect at the Hamaoka Nuclear Power Station, however, according to JAIF.

The Hamaoka plant is owned and operated by Chubu Electric Power Company.

Units 3 is not in service due to periodical inspection, and Units 4 and 5 are continuing normal operation.

FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN Washington DC Office, Update to information sheet regarding Tohoku earthquake as of 10:15AM EST (05:15 GMT), March 16, 2011:

  • Radiation Levels At 6:40AM (JST) on March 16 (21:40 GMT March 15), a radiation level of 400 milli sievert per hour was recorded outside the west side of the secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station.

  • At 6:40AM on March 16, a radiation level of 100 milli sievert per hour was recorded outside the west side of the secondary containment building of the Unit 4 reactor at Fukushima Daiichi Nuclear Power Station.

  • At 8:47AM on March 16, a radiation level of 150 milli sievert per hour was recorded outside the secondary containment building of Unit 2 reactor of Fukushima Daiichi Nuclear Power Station.

  • At 8:47AM on March 16, a radiation level of 300 milli sievert per hour was recorded between the exteriors of the secondary containment buildings of Unit 2 reactor and Unit 3 reactor of Fukushima Daiichi Nuclear Power Station.

  • At 8:47AM on March 16, a radiation level of 400 milli sievert per hour was recorded outside the secondary containment building of Unit 3 reactor of Fukushima Daiichi Nuclear Power Station.

  • At 8:47AM on March 16, radiation level of 100 milli sievert per hour was recorded outside the secondary containment building of Unit 4 reactor of Fukushima Daiichi Nuclear Power Station.

  • At 10:40AM on March 16, a radiation level of 10 milli sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.

  • At 4:10PM on March 16, a radiation level of 1530 micro sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.

  • For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.

  • Fukushima Daiichi Unit 1 reactor At 6:55AM on March 16, the pressure inside the reactor core was measured at 0.17 MPa. The water level inside the reactor core was measured at 1.8 meters below the top of the fuel rods.

  • Fukushima Daiichi Unit 2 reactor At 6:55AM on March 16, the pressure inside the reactor core was measured at 0.043 MPa. The water level inside the reactor core was measured at 1.4 meters below the top of the fuel rods.

  • Fukushima Daiichi Unit 3 reactor At 8:37AM on March 16, white smoke was observed emanating from the vicinity of the secondary containment building.

  • At 9:55AM on March 16, the pressure inside the reactor core was measured at 0.088 MPa. The water level inside the reactor core was measured at 1.9 meters below the top of the fuel rods.

  • At 11:32AM on March 16, the Japanese government announced that the possibility of significant damage to the primary containment vessel was low.

  • Fukushima Daiichi Unit 4 reactor At 4:08AM on March 15, the temperature of the spent fuel pool was measured at 183 degrees Fahrenheit.

  • At 5:45AM on March 16, a fire occurred in the vicinity of the third floor of the secondary containment building.

  • At 7:26AM on March 16, no flames or smoke was observed and thus it was concluded that the fire extinguished on its own accord.

  • Fukushima Daiichi Unit 5 reactor At 4:00AM on March 16, the temperature of the spent fuel pool was measured at 141 degrees Fahrenheit.

  • Fukushima Daiichi Unit 6 reactor At 4:00AM on March 16, the temperature of the spent fuel pool was measured at 137 degrees Fahrenheit.

  • Rokkasho Reprocessing Plant and Accompanying Facilities As of 12:00PM on March 15, power generation of all facilities was restored to the commercial electricity grid from backup power generation systems. It was confirmed that no fire, damage to equipment, injuries to personnel occurred. Radiation levels were measured at a normal level of safety.

TOKYO ELECTRIC POWER COMPANY Information on TEPCO facilities due to Tohoku-Taiheiyou-Oki Earthquake, March 16, 2011, 05:00 GMT (2:00PM JST)

NUCNET - THE NUCLEAR COMMUNICATIONS NETWORK March 16, 2011, 01:50 GMT

Efforts Continue To Cool Spent Fuel At Unit 4

Small fires have broken out inside the reactor building at unit 4 of the Fukushima-Daiichi nuclear power plant in Japan, where damaged

fuel in the spent fuel pool is leading to the uncontrolled release of

radioactive substances.

The Japan Atomic Industrial Forum (JAIF) said reactor building integrity at

unit 4 was "severely damaged", but primary containment vessel integrity was

not affected. Unit 4 was undergoing a scheduled inspection and was already

shut down when Friday's earthquake struck.

JAIF said the level of cooling water in the unit 4 spent fuel pool was low

and workers were preparing to inject water in an effort to keep the fuel

cool.

Plant operator Tokyo Electric Power Company (Tepco) said it was keeping the

area "under surveillance".

The International Atomic Energy Agency (IAEA) said there had been two fires.

The latest was seen at 21:45 central European time (CET) on 15 March, but as

of 22:15 CET of the same day, "the fire could no longer be observed", a

statement said.

Units 1, 2 and 3 at the plant are still being cooled using seawater. JAIF

said core and fuel integrity is damaged at all three units while containment

integrity damage is suspected at units 2 and 3.

There have been uncontrolled releases of radioactivity at unit 2 because the

primary containment vessel is damaged in the suppression pool sector.

At Units 5 and 6, which were already shut down at the time of the quake, the

temperature of spent fuel in the fuel pools is increasing, according to

JAIF. Measures such as ventilating the reactor building to prevent the

accumulation of hydrogen-which is what led to earlier explosions in units

1, 2 and 3-are being taken.

Radiation Measurements

Tepco has published readings from two monitoring posts near the plant's main

gate, but there have been marked fluctuations depending on events such as

controlled venting of containments and the prevailing wind direction.

On 13 March, measurements were about 20 to 120 microsieverts per hour

(microSv/hr) on 13 March; about 40 to 160 microSv/hr on 14 March; about 60

microSv/hr on 15 March.

However, according to the government's chief cabinet secretary the values

have now increased  and reached more than 1,000 microSv/hr today at 10:00

local Japan time.

On the plant site itself, various monitoring posts and mobile measuring

equipment produced much higher levels with a peak of 400 millisieverts per

hour (mSv/hr) between units 3 and 4 on 15 March.

According to samples taken outside the plant site, contamination is not at

an unacceptable or alarming level, and the 20 km evacuation zone remains in

force together with an order for people living between 20 and 30 km from the

plant to stay indoors.

Notes on Radiation

In most countries, the natural background radiation level is in the range of

0.2 to 0.5 microSv/hr (including the natural radon background radiation in

buildings) or about 2 to 4 millisieverts per year (mSv/yr).

The annual dose limit for controlled nuclear workers or medical personnel is

20 mSv/yr, but may reach 50 mSv in an exceptional year when the 5-year

average is not higher than 20 mSv, and 100 mSv in case of declared

emergencies according to recommendations by the International Commission on Radiological Protection.

NISA Releases Details Of Fukushima-Daiichi Radiation Readings

March 16, 2011 Figures from a radiation monitoring post near the main gate of the Fukushima-Daiichi nuclear power plant show the latest reading was 1,900 microsieverts per hour (microSv/hr) at 11:20 Japan time (03:20 central European time; CET) and that there was a peak indication of 6,400 microSv/hr at 10:45 Japan time.

Toshihiro Bannai of Japan's Nuclear and Industrial Safety Agency (NISA) gave

the figures to NucNet in a telephone call at midday CET.

In most countries, the natural background radiation level is in the range of

0.2 to 0.5 microSv/hr, or about 2 to 4 millisieverts per year (mSv/yr).

The annual dose limit for controlled nuclear workers or medical personnel is

20 mSv/yr and for the general public 1 mSv/yr. This means if a person had

remained at the Fukushima-Daiichi site boundary without any protection today

between 10:00 and noon, the annual dose limit would have been exceeded in

less than half an hour.

Mr Bannai also said authorities are taking every measure to keep the

temperature low of spent fuel in the storage pool at unit 4. He said fire

engines had been brought in to help pump water containing boric acid over

the spent fuel.

He said the spent fuel pool had not reached "a critical configuration" and

the last temperature reading from the pool was 84 degrees Celsius at 0400

local time on March 14.

Earlier, small fires had broken out inside the reactor building at unit 4

where damaged fuel in the spent fuel pool was leading to the uncontrolled

release of radioactive substances.

The Japan Atomic Industrial Forum (JAIF) said reactor building integrity at

unit 4 was "severely damaged", but primary containment vessel integrity was

not affected. Unit 4 was undergoing a scheduled inspection and was already

shut down when Friday's earthquake struck.

Units 1, 2 and 3 at the plant are still being cooled using seawater. JAIF

said core and fuel integrity is damaged at all three units while containment

integrity damage is suspected at units 2 and 3.

At Units 5 and 6, which were already shut down at the time of the quake, the

temperature of spent fuel in the fuel pools has been increasing, according

to JAIF. Measures such as ventilating the reactor building to prevent the

accumulation of hydrogen - which is what led to earlier explosions in units

1, 2 and 3 - are being taken.

Click here to get to NucNet's website.

NUCLEAR ENERGY INSTITUTE UPDATE AS OF 01:00 GMT, MARCH 16 At 5:45 am, March 16, Japan Standard Time (4:45 pm EDT, 20:45 GMT, March 15), a fire reignited at Tokyo Electric Power Co.'s Fukushima Daiichi 4 reactor. The fire was extinguished after about two hours, TEPCO said.

TEPCO was planning to battle the fire and provide additional water to cool used nuclear fuel with water dumped from helicopters, but abandoned the plan because a hole in the building's roof is not in close proximity of the used fuel pool.

The company may remove some panels from the top of the reactor containment buildings at reactors 5 and 6 in order to avert a possible buildup of hydrogen in the reactors. Hydrogen buildup caused explosions at reactors 1 and 3.

All of the fuel rods had been moved from reactor 4 to the spent fuel pool due to the maintenance work. About one-third of the fuel rods in reactors 5 and 6 had been removed as part of maintenance and refueling activities.

Seventy percent of the fuel rods Unit 1 and one-third in Unit 2 have been damaged, TEPCO said. The cooling water level in both units is being maintained.

Weather reports indicate that the wind at the Fukushima plant has shifted and is now blowing out to the Pacific.

An earthquake registering 6.1 on the Richter scale struck the Eastern Honshu region of Japan. Hamaoka nuclear plant, about 100 kilometers (62 miles) from the epicenter, continues to operate normally.

NEW YORK TIMES March15, 2011 20:25 GMT

Workers strain to retake control after blast and fire at Japan plant

A small crew of technicians braved radiation and fire through the day on Tuesday as they fought to prevent three nuclear reactors in northeastern Japan from melting down and to stop storage pools loaded with spent uranium fuel pods from bursting into flames.

Officials with the Tokyo Electric Power Company announced Tuesday evening that they would consider using helicopters in an attempt to douse with cold water a boiling rooftop storage pool for spent uranium fuel rods. The rods are still radioactive and potentially as hot and dangerous as the fuel rods inside the reactors if not kept submerged in water.

"The only ideas we have right now are using a helicopter to spray water from above, or inject water from below," a power company official said at a news conference. "We believe action must be taken by tomorrow or the day after."

Hydrogen gas bubbling up from chemical reactions set off by the hot spent fuel rods produced a powerful explosion on Tuesday morning that blew a 26-foot-wide hole in the outer building of Reactor No. 4 at the Fukushima Daiichi nuclear power plant. A fire there may have been caused by machine oil in a nearby facility, inspectors from the United States Nuclear Regulatory Commission said, according to an American official.

Concern remained high about the storage pools at that reactor and at two other reactors, Nos. 5 and 6. None of those three reactors at the plant, 140 miles northeast of Tokyo, were operating on Friday afternoon when an offshore earthquake with a magnitude now estimated at 9.0 suddenly shook the site. A tsunami with waves up to 30 feet high rolled into the northeast Japanese coastline minutes later, swamping the plant.

At least 750 workers evacuated on Tuesday morning after a separate explosion ruptured the inner containment building at Reactor No. 2 at the Daiichi plant, which was crippled by Friday's earthquake and tsunami. The explosion released a surge of radiation 800 times more intense than the recommended hourly exposure limit in Japan.

But 50 workers stayed behind, a crew no larger than would be stationed at the plant on a quiet spring day. Taking shelter when possible in the reactor's control room, which is heavily shielded from radiation, they struggled through the morning and afternoon to keep hundreds of gallons of seawater a minute flowing through temporary fire pumps into the three stricken reactors, Nos. 1, 2 and 3, where overheated fuel rods continued to boil away the water at a brisk pace.

See the New York Times for full story.

REUTERS March 15, 2011 20:00 GMT

U.N. atom chief sees possible Japan plant core damage Possible damage to the core of a disaster-stricken reactor and other worrying developments make it difficult to predict how Japan's nuclear emergency will develop, the U.N. atomic watchdog chief said on Tuesday.

Yukiya Amano, director general of the International Atomic Energy Agency, said he wanted more timely and detailed information from Japan-his first hint at frustration with the pace of updates from authorities in his home country.

"The problem is very complicated, we do not have all the details of the information so what we can do is limited," Amano told a news conference. "I am trying to further improve the communication."

Japanese media have criticized the government's handling of the disaster and nuclear plant operator Tokyo Electric Power Co (TEPCO) for its failure to provide enough information on the incident.

Amano said the Vienna-based U.N. agency planned to send a small team of experts to Japan, possibly to help with environmental monitoring.

See Reuters.com for full story

NUCLEAR ENERGY INSTITUTE March 15, 2011 18:15 GMT

Fukushima Daiichi-2 has damaged suppression chamber

An explosion at Unit 2 of the Fukushima Daiichi plant earlier today has damaged the suppression chamber, which holds water and steam released from the reactor core. Personnel not directly supporting recovery efforts have been evacuated from the plant, with about 50 employees remaining, principally to restore cooling water in the reactors.

Later in the day, water level inside the Unit 2 reactor was measured at 1.7 meters below the top of the fuel rods, but it was rising as workers pumped sea water into the reactor, reports said.

Tokyo Electric Power Co. said that an oil leak in a cooling water pump at Unit 4 was the cause of a fire that burned for approximately 140 minutes. The fire was not in the spent fuel pool, as reported by several media outlets. Unit 4 was in a 105-day-long maintenance outage at the time of the earthquake and there is no fuel in the reactor.

All four reactors at the Fukushima Daini power plant are shutdown and reactor coolant systems are keeping the reactors safe.

The U.S. Nuclear Regulatory Commission has sent 11 experts to Tokyo to provide assistance requested by the Japanese government. Two reactor experts were dispatched Saturday; others began departing Monday.

See NEI's website for full story.

WORLD NUCLEAR NEWS March 15, 2011 18:00 GMT

Radiation decreasing, fuel ponds warming Loud noises were heard at Fukushima Daiichi 2 this morning and a major component beneath the reactor may be damaged. Evacuation to 20 kilometres is being completed, while radiation levels decrease from a high in the morning. Concern is growing over the status of fuel cooling ponds at units 4, 5 and 6.

Confirmation of loud sounds at unit 2 this morning came from the Nuclear and Industrial Safety Agency. It noted that "the suppression chamber may be damaged." It is not clear that the 6am sounds were explosions in the usual sense.

Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system. One effect of this is that the water and steam in the torus will exist alongside a range of gases produced by the nuclear processes in the reactor.

The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

In line with the theory that non-condensed gases in the torus will be released fairly promptly and not replenished at the same rate, it is possible that the radiation release-at least via this route-will diminish and stabilize.

See World Nuclear News for full story.

BLOOMBERG March 15, 2011 17:00 GMT

Japan struck by temblor south of Tokyo A temblor struck southwest of Tokyo late yesterday and Japanese Prime Minister Naoto Kan  called for calm as the government battled to cool three damaged nuclear reactors in the northeast after the country's worst earthquake on record five days ago.

The 6.1-magnitude earthquake struck at 10:31 p.m. local time, 42 kilometers (26 miles) northeast of Shizuoka, according to the U.S. Geological Survey. Chubu Electric Power Co.'s Hamaoka nuclear plant, about 100 kilometers from the epicenter, was unaffected, Japan's Ministry of Economy, Trade and Industry said in an e-mailed statement.

The quake came as hundreds of thousands of people faced freezing temperatures with no power. Stocks plunged after news that a third explosion and fire struck Tokyo Electric Power Co.'s Fukushima plant, sending Japan's Topix 9.5 percent lower at the close in Tokyo, the largest one-day slide since October 2008. The Standard & Poor's 500 Index fell to a two-month low as global stocks also slumped.

Japan's Chief Cabinet Secretary Yukio Edano said yesterday radiation readings outside reactors rocked by explosions were falling below harmful levels, while a fire at a separate unit appeared to have been put out. Earlier, Edano said in Tokyo the steel unit containing the radioactive core of one reactor had been damaged and he warned of dangerous contamination.

See Bloomberg.com for full story.

NHK TV News Tuesday,  Update March 15, 2011

Japan's Chief Cabinet Secretary Yukio Edano says the radiation level on the premises of the quake-damaged Fukushima No. 1 nuclear power plant has been falling.

Edano told reporters on Tuesday afternoon that water is being injected steadily into the plant's No. 1 and No. 3 reactors, but that the injection of water into the No. 2 reactor is not yet stable.

Earlier in the day, radiation levels as high as 8,217 microsieverts per hour were detected around the plant's main entrance.

Edano said that although the figure is serious, the level has been falling from its momentary peak. He said he's slightly relieved by this development.

Edano said that debris from Monday's collapse of the covering of the No. 3 reactor building could be the cause of the 400 millisieverts-per-hour radiation detected around the reactor.

This level of radiation, which is high enough to affect human health, had been blamed on a fire at the plant's No. 4 reactor, which was thought to have released highly radioactive material into the air.

Edano also said temperatures in the plant's No. 5 and No. 6 reactors were gradually increasing due to malfunctioning of cooling systems affected by the quake. He added that workers are trying to prevent possible hydrogen gas explosions similar to that at the No. 4 reactor.

THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update / Brief No. 65 / 15 March 2011

Radioactivity 'Decreasing' At Fukushima-Daiichi

15 Mar (NucNet): The Japanese authorities have said the level of radioactivity has been decreasing at the Fukushima-Daiichi nuclear power plant site.

The authorities told the International Atomic Energy Agency (IAEA) that a dose rate of 11.9 millisieverts per hour (mSv/hr) was recorded at midnight UTC (01:00 Central European Time) at the main gate, and at 06:00 UTC (07:00 CET) on 15 March the rate was 0.6 mSv/hour.

The IAEA confirmed that earlier, a 400-mSv/hr dose rate was recorded at Fukushima-Daiichi between units 3 and 4.

The IAEA said in a statement: "This is a high dose-level value, but it is a local value at a single location and at a certain point in time."

The agency said it was continuing to confirm "the evolution and value" of this dose rate.

About 150 people from populations around the plant have received monitoring for radiation levels. The results have resulted in measures being taken to decontaminate 23 people.

Evacuation of the population from the 20-kilometre zone around the plant is continuing. The Japanese government has asked residents living between 20 km and 30 km of the plant to stay indoors.

The authorities have distributed iodine tablets to evacuation centres, but no decision has yet been taken on their administration.

The ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid.

Earlier today there was an explosion at unit 2 of the Fukushima-Daiichi plant and the spent fuel storage pool at unit 4 caught fire with radioactive substances being released directly into the atmosphere after partial destruction of the reactor building.

The fire in the storage pool area was probably caused by a hydrogen explosion and has now been extinguished.

The Japan Atomic Industrial Forum (JAIF) said damage is suspected to unit 2's inner or primary containment vessel (PCV).

Staff and workers, apart from 50 Tokyo Electric Power Company (Tepco) employees involved in the water injection operation trying to cool the plant's damaged reactor units 1 to 3, have been evacuated.

There was an explosion at unit 3 yesterday and at unit 1 on 12 March, but according to JAIF the PCVs at those units have not been damaged.

JAIF has issued an updated status report on all affected units:

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300189582P.pdf

Fire broke on the 4th floor of the Unit-4 Reactor Building around 6AM Tuesday 3/15 and the radiation monitor readings increased outside of the building:30mSv between Unit-2 and Unit-3, 400mSv beside Unit-3, 100mSv beside Unit-4 at 10:22.

It is estimated that the spent fuels stored in the spent fuel pit heated and hydrogen was generated from these fuels, resulting in the explosion.

TEPCO later announced the fire had been extinguished. Other staff and workers than 50 TEPCO employees, who are engaged in water injection operation, have been evacuated.  Source: Japan Atomic Industrial Forum

Bloomberg - Radiation under control at Fukushima #3

The operator of a Japanese nuclear power plant where a reactor's containment building exploded says radiation levels at the unit are within legal limits.

Tokyo Electric Power Co. says radiation levels at Unit 3 of the stricken Fukushima Dai-Ichi plant were 10.65 microsieverts Monday, significantly under the 500 microsieverts.

New York Times - Japan faces potential nuclear disaster

0900 GMT March 15, 2011

Japan's nuclear crisis verged toward catastrophe on Tuesday after an explosion damaged the vessel containing the nuclear core at one reactor and a fire at another spewed large amounts of radioactive material into the air, according to the statements of Japanese government and industry officials.

(full text of NYT report at cited URL above)

Bloomberg - March 15, 2011, 0634 GMT

Japan's Stricken Nuclear Power Plant Rocked by Blasts, Fire

March 15 (Bloomberg) -- Tokyo Electric Power Co.'s stricken nuclear power plant was today rocked by two further explosions and a fire as workers struggled to avert the risk of a meltdown.

A hydrogen blast hit the Fukushima Dai-Ichi plant's No. 4 reactor, where Tokyo Electric earlier reported a blaze, Japan's Chief Cabinet Secretary Yukio Edano said at a briefing. Four of the complex's six reactors have been damaged by explosions.

Prime Minister Naoto Kan appealed for calm as he said the danger of further radiation leaks was rising at the crippled nuclear facility, 135 miles (220 kilometers) north of Tokyo. Sea water is being pumped to cool the reactors and prevent the uncontrolled release of radioactive material.

Asia's biggest utility said the containment chamber of the No. 2 reactor may be damaged after a blast at 6:14 a.m. today and radiation leakage is possible. The explosion occurred near a suppression chamber that controls pressure in the reactor core, Tokyo Electric said.

The utility's stock was set to retreat by the daily limit of 25 percent in Tokyo. The shares failed to open for trading because of a lack of buy orders.

Today's blasts follow one at the No. 3 reactor yesterday after a buildup of hydrogen gas and a similar explosion at the No. 1 reactor on March 12.

Radiation Levels

About 140,000 people within a radius of 20 to 30 kilometers from the plant were ordered to stay indoors, Kyodo News reported, citing the prefectural government. The wind near the Fukushima plant was blowing from the east-north-east at noon, the Japan Meteorological Agency said.

Edano said earlier the vessel containing the radioactive core of the plant's No. 2 reactor was damaged in today's blast and radiation levels could harm public health.

As of 10.22 a.m. local time, radiation levels of 30 millisieverts were measured between the No. 2 and No. 3 reactors, while at the No. 3 reactor 400 millisieverts were detected, Edano said. "This is a level that could harm people," he said.

Four-hundred millisieverts is 20 times the annual limit for nuclear industry employees and uranium miners, according to the World Nuclear Association. A radiation dose of 100 millisieverts a year is the lowest level at which any increase in cancer is evident, the London-based WNA said on its website.

World Nuclear News Dramatic escalation in Japan 15 March 2011

FIRST PUBLISHED 1.22am GMT UPDATE 1: 1.58am GMT Information from TV appearance, change of headline from 'Possible damage to Fukushima Daiichi 2'

CORRECTION: 1.58am GMT Removal of potential inaccuracy on torus' status in containment

UPDATE 2: 2.19am GMT Information from government, change of headline from 'Damage to Fukushima Daiichi 2'

UPDATE 3: 3.20am GMT Details on fire from PM's spokesman

UPDATE 4: 3.44am GMT Fire reported put out

Loud noises were heard at Fukushima Daiichi 2 at 6.10am this morning. A major component beneath the reactor is confirmed to be damaged. Evacuation to 20 kilometres is being completed, while a fire on site has now been put out.

Confirmation of loud sounds at unit 2 this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that "the suppression chamber may be damaged." It is not clear that the sounds were explosions in the usual sense.

Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system.

The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

A close watch is being kept on the radiation levels to ascertain the status of containment. As a precaution Tokyo Electric Power Company has evacuated all non-essential personnel from the unit. The company's engineers continue to pump seawater into the reactor pressure vessel in an effort to cool it.

Fire put out at unit 4

Prime minister Naoto Kan confirmed a fire burning at unit 4, which, according to all official sources, had never been a safety concern since the earthquake. This reactor was closed for periodic inspections when the earthquake and tsunami hit, therefore did not undergo a rapid and sudden shutdown. It was of course violently shaken and subject to the tsunami.

Kan's spokesman Noriyuki Shikata said that there had been "a sign of leakage" while firefighters were at work, "but we have found out the fuel is not causing the fire." The fire is now reported extinguished.

Evacuation ordered

Kan has requested that evacuation from a 20 kilometer radius is completed and those between 20-30 kilometers should stay indoors. He said his advice related to the overall picture of safety developments at Fukushima Daiichi, rather than those at any individual reactor unit.

Shikata added that radiation levels near the reactors had reached levels that would affect human health. It is thought that the fire had been the major source of radiation.

Nuclear Energy Institute 0400 GMT March 15, 2011

Yukio Edano, Japan's Chief Cabinet Secretary, during a live press conference at 10 p.m. EDT, said there is a fire at Fukushima Daiichi 4 that is accompanied by high levels of radiation between Units 3 and 4 at the site.

The fire began burning at Unit 4 at around 6 a.m. Japan time on March 14 and is still burning. Fire fighters are responding to the fire. The reactor does not have fuel in the reactor, but there is spent fuel in the reactor (pool) and Edano said that he assumes radioactive substances are being released.

"The substances are coming out from the No. 4 reactor and we are making the utmost effort to put out the first and also cool down the No. 4 reactor (pool)."

Edano said that a blast was heard this morning at Unit 2 at about 6:30 a.m. A hole was observed in the number 2 reactor and he said there is very little possibility that an explosion will occur at Unit 2.

"The part of the suppression chamber seems to have caused the blast," Edano said. A small amount of radioactive substance seems to have been released to the outside.

TEPCO workers continue to pump sea water at 1, 2 and 3 reactors. "The biggest problem is how to maintain the cooling and how to contain the fire at No. 4." At 10:22 a.m. Japan time, the radiation level between units 2 and 3 were as high as 40 rem per hour. "We are talking about levels that can impact human health." Edano said.

Of the 800 staff that remained at the power plant, all but 50 who are directly involved in pumping water into the reactor have been evacuated.

World Nuclear News: Possible damage at Fukushima Daiichi 2

15 March 2011 | 0122 GMT

Loud noises were heard at Fukushima Daiichi 2 at 6.10am this morning. A major component beneath the reactor may be damaged.

Confirmation of loud sounds this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that "the suppression chamber may be damaged." It is not clear that the sounds were explosions.

Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system.

The torus is not within the primary containment structure surrounding the reactor vessel, but within the secondary containment structure of the reactor building itself.

Breaking News Alert The New York Times

0100 GMT Tuesay 3/15/11

New York Times - New Blast Reported at Japanese Nuclear Plant

An explosion early Tuesday morning may have damaged the inner steel containment vessel of the No. 2 reactor at Japan's Fukushima Daiichi Nuclear Power Station, leading to the wide release of radioactive materials there and forcing the evacuation of emergency workers, the plant's operator said.

The blast appeared to be different -- and more severe -- than those that at two other troubled reactor at the same nuclear complex because this one, reported to have occurred at 6:14 a.m., happened in the "pressure suppression room" in the cooling area of the reactor, raising the possibility to damage to the reactor's containment vessel.

Financial Times | New explosion at Japanese reactor

Published: March 13 2011 21:58 | Last updated: March 15 2011 00:27

Japanese nuclear authorities evacuated non-essential personnel from a crippled nuclear power station on Monday.

The damage occurred in part of the Fukushima Daiichi facility's No 2 reactor known as the suppression chamber, which was believed to have been filled with contaminated water and air.

The extent of the damage was unclear but elevated radiation levels were detected in the area immediately around the station. The reactor's innermost core, which holds its fuel, was said to be intact.

ABC TV News Japan Earthquake:

Another  explosion at Third Reactor at Fukushima  #2

0200 GMT March 15, 2011

Blast Came After IAEA Said Containment Vessels at Fukushima Nuclear Reactors Seem to Be Working

A new explosion at a Fukushima Daiichi nuclear plant reactor in Japan early Tuesday may have left the reactor leaking water, according to the company that runs the plant.

A senior U.S. official said the blast -- the third in three days at the plant since a powerful earthquake struck Japan on Friday -- may be more dangerous than the others.

While the two previous explosions -- at Fukushima Daiichi reactors No. 1 and 3 -- were hydrogen blasts caused by a buildup of steam in the reactor units, the new blast at reactor No. 2 has officials unsure of the cause.

In addition, the fuel rods in the reactor were melting, the official said, though the situation was not described as a meltdown.

Half of the fuel rods were exposed, not immersed in water, and the suppression pool, which holds the water used to keep the rods cool, seemed to be damaged, according to Tokyo Electric Co., which runs the plant, and government officials.

The U.S. official said water being pumped in is disappearing faster than it would if it only were caused by evaporation, which suggests there may be a leak in the reactor's containment vessel. But, the official said, it also could be that there is so much pressure inside the reactor that it is hard to pump in water.

A government official said that though the level of radiation rose around the reactor, there was no danger.

"The radioactive level near unit 2 has gone up, but at this juncture, the level is not judged to be immediately harmful to human bodies," said Noriyuki Shikata, a spokesman in the prime minister's office.

But Japanese news agency NHK reported that the radiation levels at the front gate of the Daiichi plant were so high that a person would receive more in one hour than they would receive naturally in an entire year.

The explosion, which occurred at 6:10 a.m., came shortly after the International Atomic Energy Agency announced that the reactors at the Fukushima Daiichi plant were shut down.

Japan Times - Problems persist at Fukushima #2,

but cold shut down near at units #1 & #3

A crisis continued Tuesday at the troubled No. 2 reactor at the quake-hit Fukushima No. 1 nuclear power plant, as fuel rods became fully exposed again after workers recovered water levels to cover half of them in a bid to prevent overheating.

The plant operator, Tokyo Electric Power Co., said steam vents of the pressure container of the reactor that houses the rods were closed probably due to the battery problem, raising fears that its core will melt at a faster pace.

The firm said it will first lower the pressure of the reactor by releasing radioactive steam and open the vents with new batteries to resume the operation to inject seawater to cool down the reactor.

Earlier, cooling functions of the reactor failed, causing water levels to sharply fall and fully exposing the fuel rods for about 140 minutes. TEPCO said they could not pour water into the reactor soon as it took time for workers to release steam from the reactor to lower its pressure, the government's nuclear safety agency said.

As TEPCO began pouring coolant water into the reactor, water levels went up at one point to cover more than half of the rods that measure about 4 meters.

Prior to the second full exposure of the rods around 11 p.m. Monday, radiation was detected at 9:37 p.m. at a level twice the maximum seen so far- 3,130 micro sievert per hour - near the main gate of the No. 1 plant, according to TEPCO.

* * *

TEPCO said the No. 1 and No. 2 reactors at its Fukushima No. 2 plant, which is adjacent to the No. 1 plant, have successfully cooled down to exit critical situations.

The government ordered residents within a 20-kilometer radius of the No. 1 plant to evacuate Saturday in the wake of the initial blast at the plant's No. 1 reactor. A total of 354 people are still attempting to leave the area, according to the nuclear agency.

The agency ruled out the possibility of broadening the area subject to the evacuation order for now.

TVO: Ontario's Public Educational Media Organization has uploaded a new video featuring Dr. Dan Meneley, faculty at the University of Ontario Institute of Technology and ANS Board Member, discussing the situation at the Fukushima Daiichi nuclear plant.

Start March 15, 2011 coverage

Financial Times- Japan asks for help

Published: March 13 2011 21:58 GMT | Last updated: March 14 2011 16:05

Japan issued a call for international reinforcement in its battle to prevent a potential nuclear disaster amid signs that a third reactor had gone into partial meltdown on Monday at the Fukushima power plant crippled by last week's devastating earthquake.

The International Atomic Energy Agency said Japan had requested "expert missions" to help tackle the escalating nuclear crisis. In Washington, the White House said two officials from the US Nuclear Regulatory Commission were already in Tokyo giving assistance.

Yukiya Amano, a veteran Japanese diplomat who heads the IAEA, said the agency was discussing details with Tokyo. He said: "The nuclear plants have been shaken, flooded and cut off from electricity. Operators have suffered personal tragedies."

ABC News, March 14, 2011 1630 EDT |

Japan Seeks U.S. Help With Nuclear Reactor Emergency

Asks U.S. Nuclear Commission for Help With Fukushima's Troubled Reactors.

The Japanese government formally asked the United States' Nuclear Regulatory Commission for help in stabilizing its troubled nuclear reactors in the wake of the country's massive earthquake and tsunami.

The NRC sent two boiling water reactor experts to Japan as part of a team of aid workers to help in the recovery efforts.

A series of nuclear reactors continue to deteriorate at the Fukushima Daiichi plant, raising worries of a nuclear meltdown.

After two hydrogen explosions in three days at the Fukushima Daiichi plant, a third reactor has lost its ability to cool. Officials are increasingly concerned about unit 2 at the plant.

"They continue to work hard to raise the water level to cover the fuel. Let's pray again," Tatsujiro Suzuki, vice chairman of Japan's Atomic Energy Commission, posted on Facebook today.

The fuel rods on unit 2 have been fully exposed for the second time today, a dangerous development in the effort to stop the reactor from melting down. Japanese officials said that a closed steam vent has caused a dip in the water levels, allowing the rods to be exposed, the Associated Press reported.

The exposure of the fuel rods means that the temperature in the reactor is likely to rise, which will allow it to make steam. The steam could lead to the creation of hydrogen and cause another explosion, experts said.

Knowing how long the fuel rods have been exposed is key to understanding if there is a real chance of a meltdown, said Dr. Peter Hosemann, a nuclear energy expert and professor at the University of California at Berkeley.

"Having too much of the fuel rods exposed for too long of a time can lead to the core melt. Again, if a core melt happens, the reactor pressure vessel and the containment are designed to contain it," Hosemann said.

Japanese officials acknowledged that the fuel rods appear to be melting inside all three of the reactors at the Fukashima plant.

"Although we cannot directly check it, it's highly likely happening," Chief Cabinet Secretary Yukio Edano told the Associated Press.

Experts said that the melting of the fuel rods should not be seen as an indication of imminent danger.

"The melting of the fuel rods in and of itself is not an immediate threat to the life and health of the public...there's at least three layers [of protection]: 1. The fuel is inside cladding 2. The fuel and cladding are inside the pressure vessel and 3. The fuel and pressure vessel are inside a containment bullding and that containment building is holding up well and the pressure vessel is holding up well," Dr. Edward Morse, a nuclear engineering professor at the University of California at Berkeley, said.

Officials first became concerned about unit 2 at the plant after pressure began rising in the reactor. Officials from the Tokyo Electric Power Co. told NHK News that the explosion at unit 3 might have damaged unit 2's cooling system.

Workers began pumping sea water onto the reactor following this morning's explosion. The system pumping the sea water experienced a fuel loss, causing a dip in the water levels around the rods, NHK News reported. This led to the first exposure of the rods.

"They've had trouble with getting the pumps working, with site power in general... They've shipped in extra diesel generators and they may have to do some extra retrofit plumbing," Morse said.

Workers had returned to pumping sea water when the fuel rods were exposed for a second time.

While unit 1, the first reactor to explode at the plant, appears to be stable, unit 3, which exploded early Monday morning in Japan, reportedly has a leak in its bottom.

World Nuclear News - Loss of coolant at Fukushima Daiichi 2 |

1814 GMT March 14, 2011

Serious damage to the reactor core of Fukushima Daiichi 2 seems likely after coolant was apparently lost for a period. Seawater is again being injected, but coolant level is unknown.

A spokesman for Tokyo Electric Power Company has appeard on national broadcaster NHK to explain the company's efforts to control unit 2's reactor core after its isolation cooling system failed following an increase in containment pressure to some 700 kPa.

The company prepared to inject seawater into the reactor system, but this was only started "after the water level reached the top of the fuel." Guages indicated that water levels continued to drop despite the injection process and after some time injection became impossible due to high pressure.

Opening the relief valve made injection possible again, but after a time pressure relief was again required. Injection has continued since that second venting operation but guages still do not indicate that water levels are rising.

The Japan Atomic Industry Forum reported back statements from the Nuclear and Industrial Safety Agency (NISA) saying that Tepco made a notification at 8.50pm that some fuel rods were presumed broken, based on radiation detected.

Researched and written by World Nuclear News

Guardian UK Monday 14 March 2011 19.01 GMT

Crisis deepens at Fukushima nuclear power plant in Japan

Fuel rods in three nuclear reactors at the Fukushima plant are likely to have suffered partial meltdown after series of setbacks

The situation at Japan's stricken Fukushima 1 nuclear power plant continued to deteriorate on Monday as engineers fought to save three reactors from meltdown and a second explosion at the site tore the roof off a containment building.

A series of frustrating setbacks during the day saw workers struggle to pump seawater into the reactors in a desperate attempt to cool the overheating nuclear cores.

At one point, emergency cooling at two of the reactors was suspended because the pools from which seawater was being pumped ran dry. Later in the day, a back-up pump to a third reactor ran out of fuel, causing water levels to fall so low that the fuel rods were fully exposed.

Officials at Tepco, the company that operates the power station, said it believed all three reactors were likely to have suffered partial meltdowns, though this could mean anything from one fuel rod to nearly all of them melting within the cores.

The reactors are at risk of going into meltdown because although they were automatically shut down, the fuel rods continue to give off heat. Primary and back-up power to the cooling systems was knocked out during the massive earthquake and tsunami that struck on Friday.

On Monday evening, Ryohei Shiomi, an official at Japan's Nuclear and Industrial Safety Agency (Nisa), said reactors 1 and 3 appeared stable for the time being, but that reactor two, where fuel rods were most exposed, was still a concern. "Unit 2 now requires all our effort and attention," he said.

The day began with an orange flash and a violent blast that destroyed most of the containment building around reactor 3, with debris falling back inside and onto the structure housing the reactor. The blast was caused by a buildup of hydrogen that was produced when superheated steam in the core reacted with the zirconium alloy cladding that surrounds the reactor's fuel rods.

Tepco said 11 people were injured in the accident, one seriously. A similar explosion blew the top off the reactor 1 building on Saturday morning.

Despite earlier assurances from Tepco that the steel containment vessels surrounding the reactors were undamaged in both explosions, Naoki Kumagai, a Nisa official, said "It's impossible to say whether there has or has not been damage."

Water has to cover the radioactive fuel rods in the nuclear cores completely to prevent them from overheating, but on Monday afternoon water levels dropped substantially in all three reactors, and at one point fully exposed the fuel rods in reactor 2. A spokesman for Tepco said it could not rule out a meltdown at this reactor.

Speaking about the situation at reactor 2, the government's chief cabinet secretary Yukio Edano said: "The pump ran out of fuel, and the process of inserting water took longer than expected, so the fuel rods were exposed from the water for a while."

The decision to pump salty, untreated seawater into the nuclear reactors - along with boric acid to dampen down radioactivity - is a vastly expensive last resort that effectively writes off the reactors. The plants are usually cooled by highly purified deionised water that does not damage the delicate components inside.

Engineers at the power plant face a difficult balancing act because the seawater being pumped into the reactors immediately boils and the steam is raising the pressure inside. This has to be vented before more water can be pumped in, but this releases small amounts of radioactive material into the air.

Nisa has already confirmed that caesium-137 and iodine-131 have been released into the atmosphere. These are radioactive isotopes that are produced in the core and can contaminate cooling water if fuel rods get hot enough to melt the cladding that surrounds them.

The release of radioactivity has raised health concerns and wider fears of environmental contamination. Monitoring posts to the northwest of the power station recorded radiation levels of 680 microsieverts per hour on Monday, a dose roughly equivalent to four months of natural background radiation.

An American warship, the USS Ronald Reagan, detected low levels of radiation at a distance of 100 miles from the Fukushima plant.

Radiation levels have increased in the immediate vicinity of the power station and in surrounding areas. People caught in the evacuation zone around Fukushima were given potassium iodide pills to protect against thyroid cancer. Radioactive iodine is easily absorbed by the thyroid, where it can cause tumours, but the pills saturate the gland with the element and make it harder for the radioactive form to be absorbed.

Under normal conditions, nuclear reactors produce electricity by using heat from fission reactions in the fuel rods to turn water into steam and drive turbines. Reactors 1 and 2 use uranium fuel rods, but reactor 3 uses a mixed oxide fuel, or Mox, which contains plutonium, a highly toxic substance that if released can linger in the environment for thousands of years.

The half life of plutonium is 24,000 years, meaning it takes that long for its radioactivity to drop by half.

Nuclear experts have emphasised that there are significant differences between the unfolding nuclear crisis at Fukushima and the events leading up to the Chernobyl disaster in 1986.

The Chernobyl reactor exploded during a power surge while it was in operation, which released a huge cloud of radiation because the reactor had no containment structure around it.

At Fukushima, each reactor has shut down and is inside a 20cm-thick steel pressure vessel that is designed to contain a meltdown. The pressure vessels themselves are surrounded by steel-lined, reinforced concrete shells.

"While the material is enclosed in the reactor vessel it is safe, in that it is the same radioactivity that was there in the fuel rods. The issue would come if there is a continued problem to cool down the fuel rods," said Paddy Regan, a nuclear physicist at Surrey University.

He said the worst case scenario would be "that some of the fission fragments and fuel could be widely dispersed if the vessel was to explode. This seems unlikely at present, so the next worst would likely be ongoing venting of the steam which has built up in the reactors."

Yukiya Amano, director general of the International Atomic Energy Agency, said it was "unlikely that the accident would develop" like Chernobyl.

"The Japanese authorities are working as hard as they can, under extremely difficult circumstances, to stabilise the nuclear power plants and ensure safety," Amano said in a statement.

Nuclear Energy Institute, Washington, DC, Japan reactor status update

1330 EDT 2011 03 14

Unit 2 at the Fukushima Daiichi nuclear power plant lost a significant amount of reactor coolant for a second time on Monday. Some of the uranium fuel rods were uncovered for a period of time. A malfunctioning safety relief valve at the plant caused an increase in reactor pressure and hindered injection of coolant back into the reactor. The cause of the relief valve failure is under investigation.

The Japanese government has distributed 230,000 units of potassium iodine to evacuation centers in the area surrounding the Fukushima Daiichi and Fukushima Daini stations, according to officials. Ingestion of potassium iodine can help prevent the accumulation of radioactive iodine in the thyroid.

At the Fukushima Daini site all units have off-site power, and water levels in all units are stable. Plant operators at Daini Unit 1 were able to restore a residual heat remover system, which is now being used to cool the reactor. Work is in progress to achieve a cold shutdown. Workers at Daini Units 2 and 4 are working to restore residual heat removal systems. Unit 3 is in a safe, cold shutdown.

Radiation dose rate measurements observed at four locations around the Daini plant´s perimeter over a 16-hour period on Sunday were all normal.

NHK TV Japan - Fukushima #3 nuclear plant blast injures 11

2011 03 14 0930 GMT

What appears to be another hydrogen blast has occurred at a nuclear power plant in Fukushima. No damage to the reactor chamber has been reported, but 11 people have been injured.

IAEA reported the exterior reactor building exploded but the primary containment building was not damaged. The control room of unit 3 remains operational.

The Nuclear and Industrial Safety Agency says what it believes was a hydrogen blast occurred at 11:01 AM on Monday at the No.3 reactor of Tokyo Electric Power Company's Fukushima No.1 nuclear power plant. The agency says it has so far observed no abnormal rise in radiation around the compound of the plant.

The company says the blast injured 11 people.

The Nuclear and Industrial Safety Agency has advised anyone remaining within 20 kilometers of the power plant to take shelter inside buildings as soon as possible. About 600 people are thought to be still in the area.

A similar hydrogen blast occurred at the No.1 reactor at the same plant on Saturday.

Chief Cabinet Secretary Yukio Edano told reporters that he has received a report that the latest blast has left the container of No.3 reactor intact. He said the likelihood of large volumes of radioactive materials being dispersed in the air is low.

Video footage shows that the top of the building housing the reactor has been blown off, as in Saturday's blast.

Fears of an explosion grew when the water level of the No. 3 reactor dropped, exposing fuel rods, and a reaction with the steam generated a large amount of hydrogen. The Nuclear and Industrial Safety Agency says that even if the top of the building has blown off, the reactor chamber will not be affected.

THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update  / Brief No. 60 / 14 March 2011

Second Explosion Has Not Damaged Containment, NISA Confirms

14 Mar (NucNet): Japan's Nuclear and Industrial Safety Agency (NISA) has said a hydrogen explosion that occurred today at unit 3 at the Fukushima Daiichi nuclear plant did not damage the inner or primary containment vessel (PCV).

The reactor building exploded, but the PCV remains intact. The control room of unit 3 remains operational, NISA said.

NISA said the explosion occurred 14 March 2011 at 11:01AM local Japan time.

Operator the Tokyo Electric Power Company (Tepco) said the status of the plant and the impact of radioactive materials on the outside environment are "presently under investigation".

NISA told the International Atomic Energy Agency that all personnel at the site are accounted for, but six people - two working for Tepco and two for other organisations - have been injured.

World Nuclear News - hydrogen explosion at Fukushioma #3

2010 03 14 | 0410 GMT

Another explosion has rocked the Fukushima Daiichi nuclear power plant, this time at the third reactor unit. Initial analysis is that the containment structure remains intact.

News of the explosion came at the same time as details of an earthquake but it is unclear if the events are connected.

Chief cabinet secretary Yukiyo Edamo appeared on television stating that the blast was a hydrogen explosion. He said contact had been made with the plant manager whose belief is that the containment structure, important to nuclear safety, remains intact.

The rationale for that statement, Edamo said was that water injection operations have continued and pressure readings from the reactor system were with a comfortable range.

Bloomberg - hydrogen explosion at Fukushima #3

March 14 (Bloomberg) -- A hydrogen explosion occurred at Tokyo Electric Power Co.'s Fukushima Dai-Ichi No. 3 reactor at 11:01 a.m. local time today, Japan's Ministry of Economy, Trade and Industry said.

Tokyo Electric spokesman Daisuke Hirose said smoke was seen rising from the reactor. Japan's Nuclear and Industrial Safety Agency reported earlier pressure at the reactor had fallen and Prime Minister Naoto Kan said the situation remains a concern.

BBC - To recap, in the past hour we have had reports of a new tsunami which appears to have been a false alarm, and a blast has wrecked a wall at a nuclear reactor but its containment vessel withstood the impact.

Japanese government spokesman Yukio Edano has just spoken on TV. Says that water injection at Reactor 3 seems to be continuing, and the containment vessel is still safe.

IAEA - Japan Earthquake Update (13 March 2011 21:45 CET)

The Japanese authorities have informed the IAEA that radioactivity levels at the site boundary of the Onagawa nuclear power plant have returned down to normal background levels. The first (ie lowest) state of emergency was reported at the plant earlier on Sunday after an increased level of radioactivity was detected at the site boundary. Investigations at the site indicate that no emissions of radioactivity have occurred from any of the three units at Onagawa. The current assumption of the Japanese authorities is that the increased level may have been due to a release of radioactive material from the Fukushima Daiichi nuclear power plant.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

1335 CET, 13 March 2011

Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that venting of the containment of reactor Unit 3 of the Fukushima Daiichi nuclear power plant started at 9:20 AM local Japan time of 13 March through a controlled release of vapour. The operation is intended to lower pressure inside the reactor containment.

Subsequently, following the failure of the high pressure injection system and other attempts of cooling the plant, injection of water first and sea water afterwards started. The authorities have informed the IAEA that accumulation of hydrogen is possible.

Japanese authorities have also informed the IAEA that the first (i.e., lowest) state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company. The authorities have informed the IAEA that the three reactor units at the Onagawa nuclear power plant are under control.

As defined in Article 10 of Japan's Act on Special Measures Concerning Nuclear Emergency Preparedness, the alert was declared as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation. The IAEA has offered its "Good Offices" to Japan to support the nation's response to the 11 March earthquake and tsunami. One IAEA capability intended to help member states during crises is the Response and Assistance Network (RANET). The network consists of nations that can offer specialized assistance after a radiation incident or emergency. Such assistance is coordinated by the IAEA within the framework of the Assistance Convention.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

0235 CET, 13 March 2011 -- CORRECTED

An earlier version of this release incorrectly described pressure venting actions at Units 1, 2, and 4 at the Fukushima Daini nuclear power plant. Venting did not occur at these units.

Japanese authorities have informed the IAEA that Units 1, 2, and 4 at the Fukushima Daini retain off-site power. Daini Unit 3 is in a safe, cold shutdown, according to Japanese officials.

Japanese authorities have reported some casualties to nuclear plant workers. At Fukushima Daichi, four workers were injured by the explosion at the Unit 1 reactor, and there are three other reported injuries in other incidents. In addition, one worker was exposed to higher-than-normal radiation levels that fall below the IAEA guidance for emergency situations. At Fukushima Daini, one worker has died in a crane operation accident and four others have been injured.

In partnership with the World Meteorological Organization, the IAEA is providing its member states with weather forecasts for the affected areas in Japan. The latest predictions have indicated winds moving to the Northeast, away from Japanese coast over the next three days.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

2110 CET, 12 March 2011

Japanese authorities have informed the IAEA that the explosion at Unit 1 reactor at the Fukushima Daiichi plant occurred outside the primary containment vessel (PCV), not inside. The plant operator, Tokyo Electric Power Company (TEPCO), has confirmed that the integrity of the primary containment vessel remains intact.

As a countermeasure to limit damage to the reactor core, TEPCO proposed that sea water mixed with boron be injected into the primary containment vessel. This measure was approved by Japan's Nuclear and Industrial Safety Agency (NISA) and the injection procedure began at 20:20 local Japan time.

Japan has reported that four workers at Fukushima Daiichi were injured by the explosion.

NISA have confirmed the presence of caesium-137 and iodine-131 in the vicinity of Fukushima Daiichi Unit 1. NISA reported an initial increase in levels of radioactivity around the plant earlier today, but these levels have been observed to lessen in recent hours.

Containment remains intact at Fukushima Daiichi Units 1, 2 and 3.

Evacuations around both affected nuclear plants have begun. In the 20-kilometre radius around Fukushima Daiichi an estimated 170000 people have been evacuated. In the 10-kilometre radius around Fukushima Daini an estimated 30000 people have been evacuated. Full evacuation measures have not been completed.

The Japanese authorities have classified the event at Fukushima Daiichi Unit 1 as a level 4 'Accident with Local Consequences' on the International Nuclear and Radiological Event Scale (INES). The INES scale is used to promptly and consistently communicate to the public the safety significance of events associated with sources of radiation. The scale runs from 0 (deviation) to 7 (major accident).

Japan has also confirmed the safety of all its nuclear research reactors.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Los Angeles Times - Japan making progress at Fukushima

2011 03 13 1200 EDT

Japanese officials have begun pumping seawater into a second nuclear reactor at the Fukushima No. 1 power plant 140 miles north of Tokyo to cool the reactor core in a last-ditch effort to stave off a core meltdown.

The action indicates that the reactor's normal backup cooling system has failed and is no longer able to supply fresh water to the core. Officials at Tokyo Electric Power Co., which owns the plant, have been struggling to keep six shut-down nuclear reactors cooled because seawater from the tsunami that followed Friday's magnitude 9.0 earthquake damaged the diesel generators that power the circulating pumps.

An explosion Saturday night at the No. 1 reactor destroyed the cooling system there and officials had little choice but to begin injecting seawater laced with boron directly into the reactor containment vessel. Seawater is highly corrosive, particularly when heated, and injecting it into the reactor means the company is, for all practical purposes, abandoning the reactor for all future uses.

That action at the No. 1 reactor seems to have been successful so far. Power company officials have reported that radiation levels at the plant have fallen and that the core seems to be cooling effectively.

Now they have been forced into the same decision at the No. 3 reactor at the site.

Power company officials say hydrogen gas has also been building up inside the reactor building at the No. 3 reactor. They have vented some of the gas, but fear that could lead to an explosion similar to the one that destroyed the building at reactor No. 1.

The International Atomic Energy Agency said Sunday evening that Japan had informed it that an emergency had been declared at the nearby Onagawa power plant because excessive radiation had been detected outside the plant.

Power company officials later said, however, that all three reactors at Onagawa had been safely shut down and were under control and that wind had blown the radiation there from the Fukushima plant.

On Monday morning, Japan Atomic Power said that two of the three backup diesel generators at its Tokai No. 2 facility about 75 miles north of Tokyo in Ibaraki prefecture had failed, but that the remaining generator was providing sufficient electricity to power the circulating pumps to keep the three shut-down nuclear reactors there controlled.

CNN - Workers scramble to cool reactors; official says

2011 03 13 1617 GMT

(CNN) -- Japanese efforts to prevent a nuclear meltdown by flooding reactors with seawater are a last-ditch attempt, but do not mean that a nuclear tragedy is imminent, experts said Sunday.

Nuclear experts who have followed the developments at the damaged Fukushima Daiichi nuclear plant in northeastern Japan say that despite several setbacks, the possibility of massive radiation exposure remain low -- at least for now.

Japanese officials are keeping an eye on two nuclear plants that have released radiation beyond normal levels. At the Daiichi plant in Fukushima, two of the three reactors -- Nos. 1 and 3 -- are at risk for meltdown because of the powerful earthquake and tsunami that struck on Friday. At a second plant, in Onogawa, excessive radiation levels also were recorded, though officials have told the United Nations' atomic watchdog agency that the situation is "under control."

An explosion caused by hydrogen buildup Saturday blew the roof off a concrete building housing the plant's No. 1 reactor, but the reactor and its containment system were not damaged in the explosion. Officials say the No. 3 reactor would also likely withstand a similar blast, noting that workers had already released gas from the building to try to prevent an explosion.

"I don't think we're really close to a meltdown," said Dale Klein, vice chancellor for special engineering projects at the University of Texas, referring to the Daiichi plant.

There does appear to be some fuel damage to one of the reactors, but the seawater method to keep them cool seems to be working.

Reuters - Japan agency: Onagawa plant functioning properly

2011 03 13 | 1055 EDT

(Reuters) - Japan's nuclear safety agency said on Sunday there was no problem with the cooling process at Tohoku Electric Power Co's (9506.T) Onagawa nuclear power plant and that a rise in radiation levels there was due to radiation leakage at another plant in a neighbouring prefecture.

The agency said a report from Tohoku Electric shows that cooling systems at all three reactors at the Onagawa complex, which were automatically shut after a massive earthquake and tsunami on Friday, are functioning properly.

Cooling systems at Tokyo Electric Power Co's (9501.T) Fukushima Daiichi nuclear plant were damaged by the quake and tsunami, forcing the power utility to let out air from reactor container vessels to reduce pressure built inside.

Japan nuclear health risks low, won't blow abroad Reuters

2011 03 13 | 1155 EDT

Health risks from Japan's quake-hit nuclear power reactors seem fairly low and winds are likely to carry any contamination out to the Pacific without threatening other nations, experts say.

"This is not a serious public health issue at the moment," Malcolm Crick, Secretary of the U.N. Scientific Committee on the Effects of Atomic Radiation, told Reuters.

"It won't be anything like Chernobyl. There the reactor was operating at full power when it exploded and it had no containment," he said. As a precaution, around 140,000 people have been evacuated from the area around Fukushima.

"Many people thought they'd been exposed after Three Mile Island," he said. "The radiation levels were detectible but in terms of human health it was nothing." Radiation can cause cancers.

The World Health Organization (WHO) also said the public health risk from Japan's atomic plants remained "quite low." The quake and devastating tsunami may have killed 10,000 people.

The Japan Meteorological Agency said that the winds in the area would shift from the south to a westerly on Sunday night, blowing from Fukushima toward the Pacific Ocean.

"The wind direction is right for people in Japan. It's blowing out to the Pacific," Lennart Carlsson, director of Nuclear Power Plant Safety in Sweden, told Reuters. "I don't think this will be any problem to other countries."

Crick said that time is a big help for reducing health risks since many of the most damaging nuclear effects, such as radio iodines, dissipate within hours or days. He said a meltdown can be contained in a sealed reactor.

Japan's biggest earthquake on record on Friday knocked out the back-up cooling systems at Fukushima, north of Tokyo, causing a build-up of heat and pressure. An explosion hit the plant on Saturday.

Japan has rated the Fukushima accident at four on an international scale -- meaning an accident with local consequences -- against Chernobyl which was worst at seven on the 1-7 scale. Three Mile Island rated a five.

Japan Times Monday March 14, 2011 | 1610 GMT (March 13)

Water injected into Fukushima reactor

Radioactive leak at No. 3 no health risk: Edano

Compiled from Kyodo, AP

Authorities scrambled Sunday to control an overheating reactor at the problem-prone Fukushima No. 1 nuclear power plant by injecting seawater and venting gas to reduce the pressure inside.

While acknowledging that the core of the plant's No. 3 reactor may have overheated and deformed, Chief Cabinet Secretary Yukio Edano denied it led to a meltdown of the critical fuel rods.

At a news conference, Edano said that "a very small amount" of radioactive substances had leaked from the No. 3 reactor, dismissing concerns it posed a threat to human health.

The government's top spokesman warned, however, that a hydrogen explosion similar to the one that blew up a building housing a separate reactor at the facility Saturday could occur again at this reactor.

Large amounts of hydrogen formed when the water injection procedure temporarily ran into trouble and may have filled the upper part of the building housing the No. 3 reactor, Edano said.

The developments came after the cooling systems for some of the plant's reactors failed after the magnitude 9.0 earthquake hit eastern Japan on Friday. The failure caused the core of the No. 1 reactor to partially melt Saturday, triggering fears of a nuclear disaster.

Hidehiko Nishiyama, a senior official at the Ministry of Economy, Trade and Industry, indicated Sunday that the core of the No. 3 reactor had also undergone some melting.

"I don't think the fuel rods themselves have been spared damage," he said.

The operator of the plant, Tokyo Electric Power Co., began injecting fresh water into the No. 3 reactor's core on Sunday after learning that the tops of its MOX fuel rods were sticking 3 meters out of the cooling water. The rods must be completely covered to avoid overheating.

But after trouble developed with the pump for the fresh water, the company was forced to pour seawater into it, a step that will eventually lead to the reactor's dismantlement. The desperate step, however, caused water levels to rise, Edano said.

Radiation around the reactor exceeded the legal limit to hit 1,557 microsieverts per hour at 1:52 p.m. This rate then fell to 184 microsieverts about 50 minutes later. At this level, Edano said a hydrogen explosion is unlikely to affect human health, even one occurs.

Meanwhile, radiation at the Onagawa nuclear power plant in Miyagi Prefecture shot up from late Saturday through early Sunday, Tohoku Electric Power Co. said, adding that radiation levels were low but about 700 times higher than normal.

The government's Nuclear and Industrial Safety Agency said the rise in radiation was likely caused by substances scattered by the hydrogen explosion that hit the troubled Fukushima plant on Saturday, dismissing the possibility that the Miyagi plant was to blame.

The No. 3 reactor is the sixth reactor overall linked to the Fukushima No. 1 and No. 2 plants to experience cooling failures since the massive earthquake and ensuing tsunami struck Japan on Friday. The plants sit about 11 km from each other.

The nuclear crisis is raising fears of radiation exposure.

Nineteen people who evacuated from an area within 3 km of the No. 1 plant were found to have been irradiated, joining three others already exposed, the Fukushima Prefectural Government said Sunday.

Another 160 people are feared to have been exposed as well, the government agency said.

The Fire and Disaster Management Agency said that 15 people were found contaminated with radioactive material at a hospital within 10 km of the reactor.

To measure radiation for residents who may have been exposed and determine whether they need emergency treatment, the National Institute of Radiological Sciences sent 17 doctors and experts to the city of Fukushima on Sunday.

Meanwhile, electric power companies in other regions, as well as Japan Nuclear Fuel Ltd., have dispatched 48 people to help Tepco deal with the crisis at the Fukushima power plants.

In Vienna on Saturday, the International Atomic Energy Agency said Japanese authorities had informed it that iodine pills would be distributed to residents around the Fukushima Daiichi and Daini plants.

The government and nuclear authorities said Saturday's explosion at the No. 1 reactor did not damage the steel containment vessel housing its core, noting the blast happened when vapor from the vessel turned into hydrogen and mixed with outside oxygen.

Tokyo Electric Power has begun new cooling operations to fill the reactor with seawater and pour in boric acid to prevent a criticality - a spontaneous atomic chain reaction - from occurring.

Edano said in a news conference Sunday morning that there had been no major changes in the results of radioactivity monitoring near the No. 1 reactor.

In the types of reactors involved, water is used to cool the reactor core and produce steam to turn the turbines that make electricity. The water contains two of the least dangerous forms of radioactivity now in the news - radioactive nitrogen and tritium. Normal plant operations produce both of them in the cooling water, and they are even released routinely in small amounts into the environment, usually through tall chimneys.

THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update / Brief No. 58 / 13th March 2011  1548 GMT

Cooling System Fails At Fukushima-Daiichi-3, Venting 'A Success'

13 Mar (NucNet): Tokyo Electric Power Company (Tepco) says it successfully vented the inner or primary containment vessel (PCV) at Fukushima-Daiichi unit 3 this morning after the high pressure reactor core coolant injection system stopped working.

Tepco said the venting was completed at 08:41 local Japan time. Venting is a controlled release of gases including radioactive substances via a filter system to the outside air in order to stop pressure building up.

Tepco said it then began injecting water containing boric acid, which absorbs neutrons, into the reactor system using a fire pump.

A statement said workers at the plant in northern Japan had attempted to restart the unit's cooling system, but had failed.

Unit 3 at the plant, a boiling water reactor of 760 megawatts, uses mixed-oxide (MOX) fuel and according to the Japan Safety Agency coolant levels were 2 to 3 meters below the top of the MOX fuel rods.

Tepco said it has been seeing a rise in pressure at unit 3 and there is a risk of damage to the facility, but it is working to prevent this.

Chief cabinet secretary Yukio Edano said the core of the unit-3 reactor may have been deformed due to overheating, but denied it had led to a "meltdown", a critical situation where fuel rods have melted.

Mr Edano said at a news conference that a hydrogen explosion might occur at the unit 3 reactor building because hydrogen may have accumulated during a period when cooling of the reactor was insufficient.

He said there might be a similar explosion to the one which occurred at unit 1 yesterday, but said even if an explosion occurs, the impact should not affect the pressure vessel and containment vessel.

Unit 1 at the six-unit plant has been shut down and is being inspected following yesterday's explosion. Japanese authorities confirmed last night that the explosion occurred outside the PCV, not inside. Tepco said the integrity of the PCV remains intact.

Tepco said it has been injecting seawater mixed with boric acid into the reactor in an effort to cool the nuclear fuel. This measure was approved by Japan's Nuclear and Industrial Safety Agency (NISA) and the injection procedure began at 20:20 Japan time.

Unit 2 is shut down but the backup cooling system is not working, Tepco said. Workers are trying to install equipment in order to enable cooling with seawater.

Tepco also confirmed last night that containment remains intact at Fukushima-Daiichi units 2 and 3. Units 4, 5 and 6 were already shut down for scheduled maintenance when the earthquake struck.

Unit 2 is shut down and the reactor core isolation cooling system has been injecting water to the reactor. Tepco said the reactor water level is lower than the normal level, but the water level was "steady".

Radioactivity at the boundary of Fukushima-Daiichi has exceeded statutory limits and the incident has been rated as level 4 on the IAEA's International Nuclear and Radiological Event Scale (INES).

Japan has also confirmed the safety of all its nuclear research reactors.

Reuters Partial nuclear meltdown "no disaster,": expert 2011 03 13 1406 GMT

VIENNA (Reuters) - Any partial meltdown of nuclear fuel in a quake-hit power plant in Japan "is not a disaster" and a complete meltdown is unlikely, a German industry expert said on Sunday.

Robert Engel, a structural analyst and senior engineer at Switzerland's Leibstadt nuclear power plant, said he believed Japanese authorities would be able to manage the situation at the damaged Fukushima facility north of Tokyo.

Engel was an external member of a team sent by the International Atomic Energy Agency (IAEA) to Japan after a 2007 earthquake that hit the Kashiwazaki-Kariwa plant, until then the largest to affect a nuclear complex.

"I think nobody can say at this time whether there is a small melting of any fuel elements or something like that. You have to inspect it afterwards," he told Reuters by phone.

But a partial meltdown "is not a disaster" and a complete meltdown is not likely, he said, suggesting he believed Japanese authorities were succeeding in cooling down the reactors even though the systems for doing this failed after the quake hit.

"I only see they are trying to cool the reactor, that is the main task, and they are trying to get cooling water from the sea," Engel said, stressing he did not have first-hand information about events at the Fukushima facility.

Normally, he said, the water level inside a reactor core is about 3 to 4 meters above the fuel. If the rods are not covered by water for a longer time then a core melting is possible.

"I think they will be able to manage it ... When the (reactor) containment is intact only a small amount of radioactivity can go out, like in Three Mile Island," he said referring to the 1979 nuclear accident in the United States.

At Three Mile Island, a cooling fault led to a build-up of pressure in the radioactive core and resulted in a relatively small radiation leak.

Japan was working on Sunday to prevent the fuel rods in the plant from overheating after radiation leaked into the air.

The government said a building housing a second reactor was at risk of exploding after a blast on Saturday blew the roof off the facility's No. 1 reactor, where there is believed to have been a partial meltdown of the fuel rods.

Experts say the critical issue is what has happened or is happening with the fuel -- which contains nearly all the radioactivity in the plant -- and whether and to what extent it is damaged.

If there is a fuel meltdown, it would release radioactivity, but Engel said there were barriers before it could escape into the atmosphere -- the fuel rods, reactor vessel and containment.

PLATTS What's going on with the Japanese nuclear reactors: a primer

2011 03 13 |  1311 GMT

Washington--Tokyo Electric Power began injecting sea water into a reactor at its Fukushima Daiichi nuclear power plant Saturday in an effort to maintain cooling of the unit, which lost power following an earthquake and tsunami Friday.

Tepco reported higher-than-normal levels of radioactivity at the site but did not provide numbers. Tepco said one worker in the unit 1 reactor building was sent to the hospital after receiving a radiation dose that exceeded the threshold considered as low. Earlier that day, the IAEA said radiation levels at the plant, which rose earlier, had lessened. One worker at the adjacent Fukushima Daini station was reported killed, Tepco said, but did not give the cause.

* * *

Dale Klein, a former chairman of the NRC, said in an interview Saturday that using seawater to flood Fukushima Daiichi-1's reactor core--and containment as a precautionary measure--is part of the plant's emergency planning process. "If you're near the end of your options, that's one of them," he said.

Klein said such a procedure leads him to believe the condensate tank was broken or empty or the pipes leading to it were broken because it would have been used otherwise. The condensate tank is used to provide water to the emergency core cooling system.

Klein, who chaired the NRC from July 2006 to May 2009, said future operation of the reactor "would be an economic decision that Tepco would have to make." But he said that it was his guess that the company would consider building a new one instead. "It would be a major cleanup of contaminated components and water," he said. The 460-MW unit 1 at Fukushima Daiichi (or Fukushima I) began commercial operation in 1971 and is the oldest and smallest of the Fukushima reactors.

Klein said he would characterize the quake impact on Fukushima I-1 as "more like a Three Mile Island [but] with a lot more knowledge." Operators at the Japanese unit "knew early on what they had to do, they just had trouble doing it." he said.

During the accident at the Three Mile Island-2 unit in Pennsylvania on March 28, 1979, operators mistakenly turned off the emergency core cooling system, which had automatically activated, because they erroneously believed the core was covered. The TMI-2 accident -- in which there was a partial core meltdown -- is considered the worst in US commercial nuclear power plant history but led to no deaths or injuries to plant workers, according to NRC.

The workers at Fukushima I-1 set up emergency diesel generators to provide backup power for the cooling system, but they apparently ran for only a short time before being damaged by the tsunami, Klein said. Backup power could have been provided by batteries but that typically lasts only a few hours, and damage to the surrounding area appears to have cut off the option of bringing in additional emergency diesel generators, he said.  "The earthquake had minimal impact; the tsunami had the impact," Klein said.

At early-afternoon EST Saturday, Klein said he believed there would be few fatalities due to the reactor itself, although he said the hydrogen explosion could have injured people in the plant. "I think this will be remembered for the fatalities from the quake and tsunami, not from the reactor," he said.

* * *

The problem in cooling Fukushima Daiichi-1 was officially rated an accident on the IAEA scale Saturday. The event was reported on the IAEA website as having a rating of 4 on the International Nuclear Events Scale, meaning it was an accident with local consequences, according to the agency's website. Events can be rated from 1, an "anomaly," to 7, a "major accident."

The explosion of a reactor at the Chernobyl nuclear plant in Ukraine in 1986 was a level 7 event; the partial meltdown of the core at Three Mile Island-2 was rated at level 5, IAEA said. Events rated 4 or higher are considered accidents, IAEA said.

Japanese authorities were reportedly planning to distribute potassium iodide tablets to residents around the plant. In the event of a radiation release from an accident, potassium iodide can protect the thyroid gland from possible radiation damage by blocking the absorption of radioactive iodine.

New York Times: Japanese Scramble to Avert Meltdowns as Nuclear Crisis Deepens After Quake 2011 03 13 | 1045 GMT

TOKYO - Japanese officials struggled on Sunday to contain a widening nuclear crisis in the aftermath of a devastating earthquake and tsunami, saying they presumed that partial meltdowns had occurred at two crippled reactors and that they were bracing for a second explosion, even as they faced serious cooling problems at four more reactors.

* * *

On Saturday, Japanese officials took the extraordinary step of flooding the crippled No. 1 reactor at Fukushima Daiichi Nuclear Power Station, 170 miles north of Tokyo, with seawater in a last-ditch effort to avoid a nuclear meltdown. That came after an explosion caused by hydrogen that tore the outer wall and roof off the building housing the reactor, although the steel containment of the reactor remained in place.

Then on Sunday, cooling failed at a second reactor - No. 3 - and core melting was presumed at both, said the top government spokesman, Chief Cabinet Secretary Yukio Edano. An explosion could also rock the No. 3 reactor, Mr. Edano warned, because of a buildup of hydrogen within the reactor.

"The possibility that hydrogen is building up in the upper parts of the reactor building cannot be denied. There is a possibility of a hydrogen explosion," Mr. Edano said. He stressed that as in the No. 1 unit, the reactor's steel containment would withstand the explosion.  "It is designed to withstand shocks," he said.

Officials also said they would release steam and inject water into a third reactor at the Fukushima Daiichi plant after temperatures rose and water levels fell around the fuel rods.

Cooling had failed at three reactors at a nuclear complex nearby, Fukushima Daini, although he said conditions there were considered less dire for now.

With high pressure inside the reactors at Daiichi hampering efforts to pump in cooling water, plant operators had to release radioactive vapor into the atmosphere. Radiation levels outside the plant, which had retreated overnight, shot up to 1,204 microsieverts per hour, or over twice Japan's legal limit, Mr. Edano said.

* * *

Even before Mr. Edano's statement on Sunday, it was clear from the radioactive materials turning up in trace amounts outside the reactors that fuel damage had occurred. The existence or extent of melting might not be clear until workers can open the reactors and examine the fuel, which could be months from now.

The Japanese Nuclear and Industrial Safety Agency said that as many as 160 people may have been exposed to radiation around the plant, and Japanese news media said that three workers at the facility were suffering from full-on radiation sickness.

Even before the explosion on Saturday, officials said they had detected radioactive cesium, which is created when uranium fuel is split, an indication that some of the nuclear fuel in the reactor was already damaged.

* * *

On Sunday morning, an official with Tokyo Electric Power said that the emergency cooling system at the No. 3 reactor at Daiichi had stopped working. The official, Atsushi Sugiyama, said that urgent efforts were being made to cool the reactor with water, and that, as with the first reactor, there would be a release of vapor containing trace amounts of radiation to relieve a buildup of pressure.

Japanese nuclear safety officials and international experts said that because of crucial design differences, the release of radiation at Daiichi would most likely be much smaller than at Chernobyl even if the plant had a complete core meltdown, which they said it had not.

* * *

The decision to flood the reactor core with corrosive seawater, experts said, was an indication that Tokyo Electric Power and Japanese authorities had probably decided to scrap the plant. "This plant is almost 40 years old, and now it's over for that place," said Olli Heinonen, the former chief inspector for the I.A.E.A., and now a visiting scholar at Harvard.

Mr. Heinonen lived in Japan in the 1980s, monitoring its nuclear industry, and visited the stricken plant many times. Based on the reports he was seeing, he said he believed that the explosion was caused by a hydrogen formation, which could have begun inside the reactor core. "Now, every hour they gain in keeping the reactor cooling down is crucial," he said.

But he was also concerned about the presence of spent nuclear fuel in a pool inside the same reactor building. The pool, too, needs to remain full of water to suppress gamma radiation and prevent the old fuel from melting. If the spent fuel is also exposed - and so far there are only sketchy reports about the condition of that building - it could also pose a significant risk to the workers trying to prevent a meltdown.

CNN Workers scramble to cool reactors; official says 2nd blast possible  2011 03 13  | 1120 GMT

(CNN) -- Workers continued efforts to cool down fuel rods inside two nuclear reactors Sunday as a government official warned that a second explosion could occur at the plant.

Chief Cabinet Secretary Yukio Edano said an explosion could take place in the building housing the No. 3 reactor at the Fukushima Daiichi plant in northeastern Japan.

"There is a possibility that the third reactor may have hydrogen gas that is accumulating in the reactor (that) may potentially cause an explosion," he said.

An explosion caused by hydrogen buildup Saturday blew the roof off a concrete building housing the plant's No. 1 reactor, but the reactor and its containment system were not damaged in the explosion.

Edano said the No. 3 reactor would also likely withstand a similar blast, noting that workers had already released gas from the building to try to prevent an explosion.

Workers have been scrambling to cool off fuel rods at both reactors after a massive earthquake and tsunami disabled their cooling systems. Japanese authorities have said there is a "possibility" that a meltdown has occurred in the reactors.

A meltdown is a catastrophic failure of the reactor core, with a potential for widespread radiation release.

But Japanese officials stressed that there were no indications of dangerously high radiation levels in the atmosphere around the two reactors at the Fukushima Daiichi nuclear plant in northeastern Japan. They said they were unable to confirm whether a meltdown had occurred because they cannot get close enough to the reactors' cores.

"We are continuing to monitor the radiation, but it is under control," Chief Cabinet Secretary Yukio Edano told reporters.

Edano said doctors were examining nine people who tested positive for high radiation levels on their skin and clothing.

Meanwhile, he said authorities were responding under the presumption that meltdowns had taken place in both reactors.

Workers were pumping seawater into the reactors in what one expert described as an "act of desperation" to cool them down.

As official information about the crisis trickled out, scientists and experts around the world weighed in on the situation, offering a wide range of interpretations of the events and their possible consequences.

* * *

Authorities have also detected cooling system problems at another nuclear facility in Fukushima Prefecture, the Fukushima Daini plant, but have not expressed any concerns about possible meltdowns there.

Edano said that there have not been any leaks of radioactive material at either of the affected plants. Authorities deliberately have let out radioactive steam in order to alleviate growing pressure inside both of the affected reactors.

End March 12 coverage - begin March 13 coverage

CNN ~ Fukushima Daiichi Units #1 & 3 may have damage to reactor cores

2011 03 12 |  2058 EST

Shirakawa, Japan (CNN) -- Japanese authorities are operating on the presumption that possible meltdowns are under way at two nuclear reactors, a government official said Sunday, adding that there have been no indications yet of hazardous emissions of radioactive material into the atmosphere.

The attempts to avert a possible nuclear crisis, centered around the Fukushima Daiichi facility in northeast Japan, came as rescuers frantically scrambled to find survivors following the country's strongest-ever earthquake and a devastating tsunami that, minutes later, brought crushing walls of water that wiped out nearly everything in their paths.

Chief Cabinet Secretary Yukio Edano told reporters there is a "possibility" of a meltdown at the plant's No. 1 reactor, adding, "It is inside the reactor. We can't see." He then added that authorities are also "assuming the possibility of a meltdown" at the facility's No. 3 reactor.

Multiple updates from U.S. Nuclear Regulatory Commission on Japan's nuclear crisis 2011 03 11 | 2048 EST

These are summary level updates. Click on each link for the full text (PDF files) of the agency's press releases with embedded links to additional NRC information.

NRC Experts Deploy to Japan as Part of U.S. Government Response

Two officials from the U.S. Nuclear Regulatory Commission with expertise in boiling water nuclear reactors have deployed to Japan as part of a U.S. International Agency for International Development (USAID) team. USAID is the federal government agency primarily responsible for providing assistance to countries recovering from disaster.

"We have some of the most expert people in this field in the world working for the NRC and we stand ready to assist in any way possible," said Chairman Gregory Jaczko.

The NRC has stood up its Maryland-based headquarters Operations Center since the beginning of the emergency in Japan, and is operating on a 24-hour basis.

NRC in Communication with Japanese Regulators

Officials at Nuclear Regulatory Commission headquarters in Rockville, Md., have spoken with the agency's counterpart in Japan, offering the assistance of U.S. technical experts. Should the Japanese want to make use of this expertise, NRC staffers with extensive background in boiling-water reactors are available to assist ongoing efforts.

U.S. nuclear power plants are built to withstand environmental hazards, including earthquakes and tsunamis. Even those plants that are located outside of areas with extensive seismic activity are designed for safety in the event of such a natural disaster. The NRC requires that safety-significant structures, systems, and components be designed to take into account the most severe natural phenomena historically estimated for the site and surrounding area.

NRC Continues to Track Earthquake and Tsunami Issues

Senior officials at U.S. Nuclear Regulatory Commission headquarters in Rockville, Md., are following events related to the Japanese earthquake and subsequent tsunami. In addition, the agency's regional office in Arlington, Texas, will continue to monitor the Diablo Canyon Power Plant's handling of a notice of unusual event (NOUE) at the site, near San Luis Obispo, Calif., for the duration of the event.

NRC Monitors Notice of Unusual Event at Diablo Canyon Power Plant, Tsunami Issues

The U.S. Nuclear Regulatory Commission, through its regional office in Arlington, Tex., is monitoring a notice of unusual event (NOUE) at the Diablo Canyon Power Plant, located near San Luis Obispo, Calif. Senior NRC officials are working at the agency's Rockville, Md., headquarters to coordinate NRC activities with respect to the Japanese earthquake and subsequent tsunami.

"The NRC is closely monitoring this situation as it unfolds with respect to nuclear facilities within the United States. NRC staff is working closely with its resident inspectors who are on site to ensure safe operations," said NRC Chairman Gregory Jaczko.

Pacific Gas and Electric Co. (PG&E), operator of the Diablo Canyon two-reactor plant, declared a precautionary NOUE Unusual Event at 4:23 a.m. EST today after receiving a tsunami warning from the West California Emergency Management Agency. The tsunami warning was generated after an estimated 8.9 magnitude earthquake occurred off the eastern Japanese coast.

The licensee reported the Diablo Canyon plant is stable and both units remain on line. The plant is well protected against tsunami conditions as required by NRC regulations. The NRC has staff at the plant keeping track of the plant's response.

Washington Post ~ Japanese nuclear plants' operator scrambles to avert meltdowns 2011 03 12 2058 EST

Tokyo Electric Power Co., owner of two heavily damaged nuclear power complexes near the center of Friday's earthquake, told Japanese regulators Sunday that it faced a new emergency at one of its 10 reactors, even as it struggled to bring several others under control.

Earlier, the big electric utility took the unprecedented step of pumping seawater mixed with boric acid into the core of Fukushima Daiichi's unit 1 reactor to tame ultra-high temperatures from fuel rods that had been partially exposed.

* * *

Tokyo Electric said it had also vented or planned to vent steam and gas containing small amounts of radioactivity from seven of its reactor units. The company said that one employee, who had been working inside a reactor building, had been hospitalized for radiation exposure.

* * *

The evacuation, wider than announced the day before, followed an explosion Saturday that destroyed a building that housed both the reactor vessel and its containment building. Four workers were injured, but Japanese authorities said the containment building was intact.

The explosion was yet another indicator of dire problems inside Fukushima Daiichi unit 1, problems that might be plaguing other units as well. The explosion was caused by hydrogen, which nuclear experts said could only have been produced from inside the reactor vessel by the exposure of zirconium cladding that surrounds the fuel rods. Those rods are supposed to be covered by water, but at extremely high temperatures, steam reacts with the zirconium and produces hydrogen.

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When pressure rose in the reactor vessel, it vented the gas into the containment building that surrounds it for just such an emergency. But experts believe that devices designed to ignite the hydrogen before it reached dangerous levels were not working because of power failures.

Those power failures helped start the crisis at the nuclear plants. After grid power was knocked out by the quake, the tsunami flooded and disabled backup diesel generators, and battery power ran out. Margaret Harding, a U.S. nuclear safety consultant in touch with experts in Japan, said that the entire complex was blacked out for a period of time before new backup generators arrived.

* * *

Experts said that the decision to pump seawater into the unit was a recognition that the elaborate system of valves, pumps and pipes, and the layers of steel and concrete, might not be enough to guarantee that the nuclear facility could avoid a disaster of Chernobyl proportions.

The water and boric acid would absorb neutrons, Tokyo Electric said. But experts said it would also make it unlikely that the plant would operate again.

"We're past worrying about ruining the reactor," said Victor Gilinsky, another former commissioner at the U.S. Nuclear Regulatory Commission. "It's gone."

Already, Tokyo Electric reported that radiation levels next to the unit 1 building had increased nearly a hundredfold.

The Nuclear Energy Institute said that the incident at Fukushima Daiichi had received a rating of 4 on its 7-point International Nuclear and Radiological Event Scale, lower than the 5 earned by the 1979 Three Mile Island incident in Pennsylvania and the 7 earned by the 1986 Chernobyl disaster.

Wall Street Journal ~ Japan Quake Damage Mounts; Reactor Watched

2011 03 112 2037 EST

Japan Chief Cabinet Secretary Yukio Edano said Sunday the problems with abnormal pressures and radiation levels at the stricken Daiichi nuclear power plant in Fukushima Prefecture are "not deteriorating" and that they are continuing with the plan to pump water into the No. 1 reactor that was hit by an explosion on Saturday.

However, Mr. Edano said the No. 3 reactor at the Daiichi facility wasn't having external water injected into the container and that slightly radioactive steam was being released to avoid a dangerous buildup in pressure. Earlier, officials from Nuclear and Industrial Safety Agency said the No. 3 unit had lost its cooling functions.

Japanese authorities have been struggling to contain the reactors at the facility since the earthquake knocked out power for the cooling system and emergency generators were flooded by water from the tsunami that followed the quake.

Mr. Edano said there were no risks to the general public from the release of radioactive steam. However, he acknowledged that nine people have been affected by radiation coming from the plant.

New York Times - Japan Floods Nuclear Reactor Crippled by Quake in Effort to Avert Meltdown 2011 03 12 | 2103 EST

TOKYO - Japanese officials took the extraordinary step on Saturday of flooding a crippled nuclear reactor with seawater in a last-ditch effort to avoid a nuclear meltdown, as the nation grappled simultaneously with its worst nuclear accident and the aftermath of its largest recorded earthquake.

A radiation leak and explosion at the Fukushima Daiichi Nuclear Power Station on Saturday prompted the government to expand an evacuation order to affect 170,000 people in the plant's vicinity. And the plant's operator issued an emergency notice early Sunday morning that a second reactor at the same aging plant was also experiencing critical failures of its cooling system, and that a way to inject water into the reactor to cool it was urgently being sought.

The government said that radiation emanating from the first reactor appeared to be decreasing after the blast on Saturday afternoon destroyed part of the facility, and they said that they had filled it with seawater to prevent full meltdown of the nuclear fuel. That step would be taken only in extreme circumstances because ocean water is likely to permanently disable the reactor.

The Japanese Nuclear and Industrial safety agency said as many as 160 people may have been exposed to radiation around the plant.

(Read rest of long article at cited URL above)

CNN - Third reactor may be overheating 2011 03 12 2030 EST

Shirakawa, Japan (CNN) -- A meltdown may be occurring at one of the reactors at a damaged nuclear power plant in northeast Japan, a government official said Sunday morning, sparking fears of a widespread release of radioactive material at a time when rescuers are frantically scrambling to find survivors from the country's strongest-ever earthquake.

Toshihiro Bannai, an official with Japan's nuclear and industrial safety agency, said officials have injected sea water and boron into the reactor at the Fukushima Daiichi facility in an effort to cool its nuclear fuel. He expressed confidence that efforts to contain the crisis would be successful.

A state of emergency has been declared for three reactors at the facility, the same place where an explosion late Saturday injured four people.

Ichiro Fujisaki, Japan's ambassador to the United States, told CNN from Washington minutes after the announcement that he did not know of any "evidence" of a meltdown. A meltdown is a catastrophic failure of the reactor core, with a potential for widespread radiation release.

Meanwhile, another reactor at the same facility failed Sunday morning -- bringing to three the number of units there that are experiencing major problems in cooling radioactive material, Chief Cabinet Secretary Yukio Edano said. Officials are working to release radioactive steam in order in order to relieve pressure in the reactor.

"A very small amount of radiation has been emitted into the air, although the level is not hazardous," Edano said.

About 180,000 people are being evacuated from within 10 to 20 kilometers (6 to 12 miles) of the Daiichi plant -- which is in addition to the thousands that have already been taken away who live closer by. More than 30,000 more people were being evacuated from their homes within 10 kilometers of the Fukushima Daiini nuclear facility located in the same prefecture.

The news of the possible meltdown came as rescue efforts resumed Sunday morning in areas devastated by the 8.9-magnitude quake and subsequent tsunami, which unleashed a wall of seawater that decimated entire neighborhoods.

Reuters - Quake-hit Japan nuclear plant faces fresh threat 2011 03 12  |1855pm EST

FUKUSHIMA, Japan (Reuters) - Japan battled to contain a radiation leak at an earthquake-crippled nuclear plant on Sunday, but faced a fresh threat with the failure of the cooling system in a second reactor.

Operator TEPCO said it was preparing to release some steam to relieve pressure in the No.3 reactor at the plant 240 km (150 miles) north of Tokyo -- which would release a small amount of radiation -- following an explosion and leak on Saturday in the facility's No. 1 reactor.

The government insisted radiation levels were low following Saturday's explosion, saying the blast had not affected the reactor core container, and the International Atomic Energy Agency (IAEA) said it had been told by Japan that levels "have been observed to lessen in recent hours."

But Japan's nuclear safety agency said the number of people exposed to radiation from the Fukushima Daiichi plant could reach 160. Workers in protective clothing were scanning people arriving at evacuation centers for radioactive exposure.

Around 140,000 people had been evacuated from areas near the plant and another nuclear facility nearby, while authorities prepared to distribute iodine to people in the vicinity to protect them from radioactive exposure.

"There is radiation leaking out, and since the possibility (of being exposed) is high, it's quite scary," said Masanori Ono, 17, standing in line on Saturday to be scanned for radiation at an evacuation center in Fukushima prefecture.

Before news of the problem with reactor No. 3, the nuclear safety agency said the plant accident was less serious than both the Three Mile Island accident in 1979 and the 1986 Chernobyl nuclear disaster.

An official at the agency said it has rated the incident a 4 according to the International Nuclear and Radiological Event Scale (INES). Three Mile Island was rated 5 while Chernobyl was rated 7 on the 1 to 7 scale, the official said.

NO REPEAT OF CHERNOBYL - EXPERTS

The blast at the nuclear plant raised fears of a meltdown at the power facility.

Experts had earlier said Japan should not expect a repeat of Chernobyl. They said pictures of mist above the plant suggested only small amounts of radiation had been expelled as part of measures to ensure its stability, far from the radioactive clouds Chernobyl spewed out 25 years ago.

Plant operator TEPCO has had a rocky past in an industry plagued by scandal. In 2002, the president of the country's largest power utility was forced to resign along with four other senior executives, taking responsibility for suspected falsification of nuclear plant safety records.

THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update  / Brief No. 57 / 13th March 2011 1823 EST

Japan Says Containment Are Intact At All Fukushima-Daiichi Units

13 Mar (NucNet): Japanese authorities have confirmed that the explosion at unit 1 of the Fukushima-Daiichi plant occurred outside the primary containment vessel (PCV), not inside. The plant operator, Tokyo Electric Power Company (Tepco), has confirmed that the integrity of the primary containment vessel remains intact.

Tepco has also confirmed to the International Atomic Energy Agency (IAEA) that containment remains intact at Fukushima-Daiichi units 1, 2 and 3.

Units 3, 4 and 5 were already shut down for scheduled maintenance when the earthquake struck.

As a countermeasure to limit damage to the unit 1 reactor core, Tepco proposed that sea water mixed with boron be injected into the primary containment vessel. This measure was approved by Japan's Nuclear and Industrial Safety Agency (NISA) and the injection procedure began at 20:20 Japan time.

The IAEA said in a statement that Japan has reported that four workers at Fukushima-Daiichi were injured by the explosion. Tepco said in a statement at 02:00 Japan time on 13 March 2011 that two workers at the site were unaccounted for.

NISA has confirmed the presence of caesium-137 and iodine-131 in the vicinity of Fukushima-Daiichi unit 1. NISA reported an initial increase in levels of radioactivity around the plant earlier today, but these levels have lessened in recent hours.

Evacuations around two affected nuclear plants have begun. In the 20-kilometre radius around Fukushima-Daiichi an estimated 170,000 people have been evacuated. In the 10-kilometre radius around the Fukushima-Daini plant an estimated 30,000 people have been evacuated. Full evacuation measures have not been completed, the IAEA said.

Radioactivity at the boundary of Fukushima-Daiichi has exceeded statutory limits and the incident has been rated as level 4 on the IAEA's International Nuclear and Radiological Event Scale (INES).

Japan has also confirmed the safety of all its nuclear research reactors.

Reuters - Snap Analysis: How bad is the nuclear accident in Japan?

2011 03 12 | 1243 EST

(Reuters) - The Japanese nuclear safety agency rated the damage at a nuclear power plant at Fukushima at a four on a scale of one to seven, which is not quite as bad as the Three Mile Island accident in the United States in 1979, which registered a five. But what does that mean?

The International Atomic Energy Agency -- an inter-governmental organization for scientific co-operation in the nuclear field -- said it uses the scale to communicate to the public in a consistent way the safety significance of nuclear and radiological events.

The International Nuclear and Radiological Event Scale (INES) ranges from one to seven with the most serious being a seven referred to as a "major accident", while a one is an "anomaly". The scale is designed so the severity of an event is about ten times greater for each increase in level.

The Chernobyl explosion in the Ukraine in 1986, the worst nuclear power accident ever, was rated a seven. That was the only event classified as a major accident in nuclear power history, exploded due to an uncontrolled power surge that damaged the reactor core, releasing a radioactive cloud that blanketed Europe.

The Three Mile Island accident in Pennsylvania was a partial core meltdown in which the metal cladding surrounding the fuel rods started to melt. That metal surrounds the ceramic uranium fuel pellets, which hold most of the radiation and power the reactor.

Nuclear reactors operate at between 550 and 600 degrees F (between 288 and 316 degrees C). The metal on the fuel rods will not melt until temperatures are well above 1000 degrees F. The ceramic uranium pellets themselves won't melt until about 2000 degrees.

About half the reactor core at Three Mile Island melted before operators restored enough cooling water to stop the meltdown. The core holds the uranium fuel rods, which must be cooled by water to prevent overheating.

So what happened at Fukushima?

The blast at the 40-year-old Daiichi 1 reactor came as plant operator Tokyo Electric Power Co (Tepco) worked to reduce pressure from mildly radioactive steam in the core after the total loss of power needed to keep water circulating to prevent the reactor fuel from overheating.

That blast led to fears of a disastrous meltdown at the plant, which automatically shut after the quake, even though the government has insisted that radiation levels were low.

The cause and exact location of the blast still needs to be established, nuclear experts queried about the incident said.

A couple of examples of fours on the INES scale include a fatal overexposure of workers following an incident at a nuclear facility at Tokaimura, Japan in 1999 and the melting of one channel of fuel in the reactor -- though no radiation was released outside the site -- at Saint Laurent des Eaux, France in 1980.

Kyodo wire service - Blast did not involve reactor: Japan spokesman

TOKYO (Kyodo) -- Japanese authorities have confirmed there was an explosion at the Fukushima No. 1 nuclear power plant Saturday afternoon but it did not occur at its troubled No. 1 reactor, top government spokesman Yukio Edano said.

The chief Cabinet secretary also told an urgent press conference that the operator, Tokyo Electric Power Co., has confirmed there is no damage to the steel container housing the reactor.

Edano said the 3:36 p.m. explosion resulted in the roof and the walls of the building housing the reactor's container being blown away. [The primary containment structure was not affected by the event.]

The authorities expanded an evacuation area for all local residents from a 10-kilometer radius of the Fukushima No. 1 and No. 2 plants to a 20-km radius.

Bloomberg - Evacuation zone widened to 20 km 2011 03 12 | 1158 EST

March 13 (Bloomberg) -- Japanese officials battling to prevent a meltdown at a nuclear power station after Friday's record earthquake are using seawater to try and cool a reactor and prevent damage to the chamber holding its radioactive core.

An explosion at Tokyo Electric Power Co.'s Fukushima Dai- Ichi nuclear power station yesterday destroyed the walls of its No. 1 reactor building and injured four people. A hydrogen leak caused the blast, which didn't damage the steel chamber, Chief Cabinet Secretary Yukio Edano said at a briefing yesterday.

Asia's biggest utility "has decided to fill the containment with seawater," Edano said. Japan's Nuclear Safety Agency couldn't confirm a meltdown at the plant and monitoring around the reactor is showing that radiation is falling, spokesman Shinji Kinjyo said today.

Fuel Rods

Fuel rods at the reactor may be melting after radioactive Cesium material left by atomic fission was detected near the site, Nuclear and Industrial Safety Agency spokesman Yuji Kakizaki said yesterday.

"If the fuel rods are melting and this continues, a reactor meltdown is possible," Kakizaki said. A meltdown refers to a heat buildup in the core of such intensity it melts the floor of the reactor containment housing.

Evacuation Zone

The government widened the evacuation zone around the damaged reactor to 20 kilometers from 10 kilometers, affecting thousands of people.

New York Times - Major meltdown not imminent 2011 03 12 | 1115 EST

Radiation Leaks Said to Recede After Blast at Japan Nuclear Plant

TOKYO - An explosion at a nuclear power plant in northern Japan on Saturday blew the roof off one building and destroyed the exterior walls of a crippled reactor, but officials said radiation leaks from the plant were receding and that a major meltdown was not imminent.

Japanese television showed a cloud of white-gray smoke from the explosion billowing up from a stricken reactor at the Fukushima Daiichi Nuclear Power Station Saturday afternoon, and officials said the threat of ongoing radiation leaks prompted them to expand the evacuation area around the facility to a 12-mile radius.

Although safety officials described the release of radioactive materials as small, they also told the International Atomic Energy Agency that they were making preparations to distribute iodine, which is used to help protect from radiation exposure, to people living near two nuclear plants that suffered damage in the quake. Japanese news media said three workers at the Daiichi plant had suffered radiation exposure.

Government officials and executives of Tokyo Electric Power, which runs the plant, gave confusing accounts of the causes of the explosion and the damage it caused. Late Saturday night, officials said that the explosion occurred in a structure housing turbines near the No. 1 reactor at the plant rather than inside the reactor itself.

The blast, apparently caused by a sharp build-up of pressure after the reactor's cooling system failed, destroyed the concrete structure surrounding the reactor but did not collapse the critical steel container inside, they said. They said that raised the chances they could prevent the release of large amounts of radioactive material and could avoid a core meltdown at the plant.

"We've confirmed that the reactor container was not damaged. The explosion didn't occur inside the reactor container. As such there was no large amount of radiation leakage outside," Japan's Chief Cabinet Secretary Yukio Edano said in a news conference Saturday evening. "At this point, there has been no major change to the level of radiation leakage outside, so we'd like everyone to respond calmly."

Tokyo Electric Power, which operates the plant, which is located 160 miles north of Tokyo, now plans to fill the reactor with sea water to cool it down and reduce pressure. The process would take five to 10 hours, Mr. Edano said, expressing confidence that the operation could "prevent criticality."

The company also said its workers also added boric acid to the containment vessel Saturday night to slow down the nuclear reaction.

* * *

Officials said even before the explosion that they had detected cesium, an indication that some of the nuclear fuel in the reactor was already damaged. That suggests that the plant experienced a partial meltdown. But officials insisted the fuel damage was contained and that the prospect of more radioactive leaks had receded.

Naoto Sekimura, a professor at Tokyo University, told NHK, Japan's public broadcaster, that "only a small portion of the fuel has been melted. But the plant is shut down already, and being cooled down. Most of the fuel is contained in the plant case, so I would like to ask people to be calm."

* * *

Malfunctioning cooling systems allowed pressure to build up beyond the design capacity of the reactors. Early Saturday officials had said that small amounts of radioactive vapor were expected to be released into the atmosphere to prevent damage to the containment systems and that they were evacuating tens of thousands of people living around the plants as a precaution.

Those releases apparently did not prevent the buildup of hydrogen inside the plant, which ignited and exploded Saturday afternoon, government officials said. They said the explosion itself did not increase the amount of radioactive material being released into the atmosphere, but they expanded the evacuation area around the Daiichi plant from a six-mile radius to a 12-mile radius.

Safety officials continued to insist that the levels of radiation were not large enough to threaten the health of people outside the plants, but they also told people living in the vicinity to cover their mouths and stay indoors.

* * *

Yasuko Kamiizumi contributed reporting from Tokyo, Alan Cowell from Paris and Ken Belson from New York.

Economist: Explosion at Japanese nuclear plant 2011 03 12 1549 GMT

Two aftershocks of yesterday's quake rattled northeastern Japan between 10:20 and 10:40 pm, measuring 4.8 and 6.0 in magnitude. Yesterday's 8.8 magnitude earthquake set off the automatic shut-down systems in ten of Japan's 55 nuclear power plants, from which the country gets a third of its energy.

At  3:36 pm Japan time the Fukushima Daiichi (number one) building exploded following reported tremors, billowing plumes of smoke into the atmosphere. Yukio Edano, the government's chief cabinet secretary, said that the reactor's nuclear containment vessel did not suffer a meltdown or explode, citing the plant's operator, Tokyo Electric Power Company (TEPCO).

The explosion, he said, was due to hydrogen buildup in the steam piping that mixed with oxygen, and that there was no damage to the container with the nuclear fuel. TEPCO has been filling the container with seawater combined with boric acid to cool the reactor, which Mr Edano called an "unprecedented" remedy. Boric acid, as well as being a strong neutron absorber to prevent the nuclear fuel from overheating, will also make the reactor much harder to get running again.

Four workers were injured from the blast and another person is reported dead. The hourly radiation following the blast was 1,015 micro sievert, a level of exposure that is considered acceptable per person per year. But it has since been falling steadily, according to TEPCO.

The government has ordered the evacuation of people within a  20 kilometer radius of Fukushima Dai-ichi, and a 10km radius of a second reactor nearby. "We wanted to play it safe," Mr Edano said.

NucNet - THE NUCLEAR COMMUNICATIONS NETWORK

Japan Update / Brief No. 56 / 12 March 2011  1123 EST / 1623 GMT

Radiation Leak At Fukushima-Daiichi Rated INES Level 4

12 Mar (NucNet): Radioactivity at the boundary of the Fukushima-Daiichi nuclear power plant in northern Japan has exceeded statutory limits and the incident has been rated as level 4 on the International Atomic Energy Agency' International Nuclear and Radiological Event Scale (INES).*

The Japanese authorities did not give any radiation measurements in their INES report to the IAEA, but plant operator Tokyo Electric Power Co. (Tepco) said earlier that radiation levels next to unit 1's machine building had increased from 0.07 millisieverts per hour (mSv/hr) to 6.7 mSv/h and around the buildings measurements have shown an increase from 0.7 mSv to 5.3 mSv. Normal background radiation levels would be 0.07 mSv/hr.

Tepco confirmed that it has successfully vented the containment of unit 1 at Fukushima-Daiichi and was preparing to vent units 2 and 3, which also shut down automatically when the 8.9-magnitude earthquake hit yesterday.

Venting is designed to reduce pressure in the containment. It is not yet known why the pressure increased.

Noriyuki Shikata, deputy cabinet secretary for public relations and director of global communications at the prime minister's office, said Tepco's efforts to depressurise unit 1's containment was successful.

"Additional measures are now being taken tonight using sea water and boric acid," he said, commenting on methods  being used to cool the plant's reactors and containments.

He said an explosion earlier today at the plant was caused by accumulated hydrogen combined with oxygen in the space between containment and outer structure. He said there was no damage to the containment.

* The International Nuclear and Radiological Event Scale

The International Nuclear and Radiological Event Scale (INES) was developed by the IAEA and the OECD in 1990 to better communicate and standardise the reporting of nuclear incidents or accidents to the public.

INES explains the significance of events from a range of activities, including industrial and medical use of radiation sources, operations at nuclear facilities and transport of radioactive material.

Events are classified on the scale at seven levels: Levels 1-3 are called "incidents" and Levels 4-7 "accidents". The scale is designed so that the severity of an event is about 10 times greater for each increase in level on the scale.

Events without safety significance are called "deviations"

and are classified Below Scale / Level 0.

Chernobyl rated as 7 (Major Accident) on the scale and Three Mile Island rated 5 (Accident with Wider Consequences).

7 Major Accident

6 Serious Accident

5 Accident With Wider Consequences

4 Accident with Local Consequences

3 Serious Incident

2 Incident

1 Anomaly

0 Below Scale/No Safety Significance

CBS News -  Meltdown most unlikely - Ian Hore Lacy WNA |2011 03 12 | 1020 EST

The explosion at a nuclear plant in Fukushima, Japan destroyed a building that houses a reactor Saturday, triggering a radiation leak and fears of a nuclear meltdown.

But a representative of the global nuclear power industry asserts the possibility of a meltdown is "diminishing by the hour," making a meltdown "most unlikely."

Ian Hore-Lacy, director of communications of the World Nuclear Association, told "Early Show on Saturday Morning" co-anchor Russ Mitchell the situation is "less dangerous than it was yesterday. The challenge remains to keep the fuel cool in the reactor, particular they that number one unit of the Fukushima Dai-ichi plant.

* * *

Hore-Lacy said they should just "sit tight and watch. It's really -- I mean that hydrogen explosion ... was a surprise. But hydrogen is always a factor in any nuclear reactor, but I think that the focus here has been on keeping the things cool, and obviously there was a hydrogen buildup somewhere and (it led to the explosion). ... But that was a bit of a diversion. I don't think it's increased the risk of radiation release at all. There is a slight risk of radiation release, but not, I think, of any magnitude. And there is a possibility that some fuel may be damaged. But I think that a meltdown, particularly at this stage, some 30 hours after shutdown, is most unlikely."

He observed that Japanese nuclear plants are constructed with earthquakes in mind, saying, "They're all built in the secure knowledge that they'll almost certainly have to endure serious earthquakes during their lifetime. And the reactors themselves are built in a very robust way, on solid rock. And I think, with all the earthquakes that have been in Japan, I don't think any of the basic reactor structures have ever been damaged. Although, of course, all the services around are liable to be damaged."

At 20:30 local time Japan Sat 3/12/11 Chief Cabinet Secretary Edano announced at the press conference as follows:

1. Hydrogen explosion occurred at 15:36 between containment and reactor building of Fukushima Daiichi unit 1.  Walls of reactor building were blown out or damaged.

2. It was confirmed that unit 1 containment integrity was maintained. Explosion was not inside the containment as it is inert.

3. Radiation level at the Fukushima Daiichi site border once increased when containment vent was conducted and reached 1,015 micro Sv per hour around the time when explosion occurred; however, the radiation level turned to decrease after the explosion down to 860 at 15:40 and 70.5 micro Sv per hour at 18:58.

4. Government has agreed to TEPCO decision to fill the entire containment up with sea water.  The filling sea water will contain boron.  TEPCO started the work for filling up at 20:20.

Reuters - Reactor core intact - No repeat of Chernobyl disaster for Japan-experts 2011 03 12 | 1411 GMT

* Experts discount threat of "Japanese Chernobyl"

* Better design key to safety concerns

BRUSSELS, March 12 (Reuters) - Japan should not expect a repeat of the Chernobyl nuclear disaster after an explosion blew the roof off one of its nuclear power plants that had been shaken in a huge earthquake, experts said on Saturday.

Japan's Daiichi 1 reactor north of the capital Tokyo began leaking radiation after the 8.9-magnitude earthquake triggered a tsunami, and swiftly prompted fears of a nuclear meltdown.

But experts said pictures of mist above the plant suggested only small amounts of radiation had been expelled as part of measures to ensure its stability, far from the radioactive clouds that Chernobyl spewed out when it exploded in 1986.

"The explosion at No. 1 generating set of the Fukushima nuclear plant in Japan, which took place today, will not be a repetition of the Chernobyl nuclear disaster," said Valeriy Hlyhalo, deputy director of the Chernobyl nuclear safety centre.

"Apart from that, these reactors are designed to work at a high seismicity zone, although what has happened is beyond the impact the plants were designed to withstand," Hlyhalo said.

"Therefore, the consequences should not be as serious as after the Chernobyl nuclear disaster."

Japanese officials said on Saturday that the nuclear reactor's core was intact, and that sea water would be poured into the leaking reactor to cool it down and reduce pressure in the unit -- a statement that should calm any fears.

Experts said it was crucial to make sure the steel reactor container had not been shattered in the explosion or in the earthquake.

Robert Grimes, professor of materials physics at Imperial College London, said earlier it had seemed that back-up generators had failed and had allowed pressure to build up.

"It does seem as if the back-up generators although they started initially to work, then failed," Grimes told BBC television, adding that the explosion was probably the large release of that pressure.

"If it's that, then we're not in such bad circumstances ... Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained.

Most experts said the relatively slight damage to the reactor was testimony to the improved security of nuclear power, something that has convinced more governments to adopt the technology in recent years despite environmentalists' concerns.

"We must remember that there are 55 reactors in Japan and this was a huge earthquake, and as a test of the resilience and robustness of nuclear plants it seems they have withstood the effects very well," Regan said. (Editing by Jon Boyle)

CNN - Japan to pump sea water into reactor containment building 2011 03 12 | 0800 EST

(CNN) -- An explosion at an earthquake-damaged nuclear plant was not caused by damage to the nuclear reactor but by a pumping system that failed as crews tried to bring the reactor's temperature down, Chief Cabinet Secretary Yukio Edano said Saturday.

The next step for workers at the Fukushima Daiichi plant will be to flood the reactor containment structure with sea water to bring the reactor's temperature down to safe levels, he said. The effort is expected to take two days.

Radiation levels have fallen since the explosion and there is no immediate danger, Edano said. But authorities were nevertheless expanding the evacuation to include a radius of 20 kilometers (about 12.5 miles) around the plant. The evacuation previously reached out to 10 kilometers.

The explosion about 3:30 p.m. Saturday sent white smoke rising above the plant a day after a massive earthquake and tsunami crippled cooling systems at the plant in northeastern Japan. Four workers were injured in the blast.

The exact circumstances of the explosion remained unclear. Kyodo News Agency, citing Tokyo Electric Power Company, reported that the roof of a reactor at the plant collapsed after the explosion.

The Fukushima prefecture government said hourly radiation levels at the plant had reached levels allowable for ordinary people over the course of a year, Kyodo reported.

Earlier Saturday, Japan's nuclear agency said workers were continuing efforts to cool fuel rods at the plant after a small amount of radioactive material escaped into the air.

The agency said there was a strong possibility that the radioactive cesium monitors detected was from the melting of a fuel rod at the plant, adding that engineers were continuing to cool the fuel rods by pumping water around them.

A spokesman for Japan's Nuclear and Industrial Agency earlier said atomic material had seeped out of one of the five nuclear reactors at the Daiichi plant, located about 160 miles (260 kilometers) north of Tokyo.

Authorities evacuated people living near the reactor after the earthquake and tsunami crippled cooling systems there, as well as at another Tokyo Electric Power Company nuclear plant in Japan's Fukushima Prefecture.

By late Saturday, authorities had extended the evacuation area to 20 kilometers around the Daiichi plant, Kyodo reported.

Reuters - Japan to fill leaking nuke reactor with sea water 2011 03 12 | 1237 GMT

TOKYO, March 12 (Reuters) - Tokyo Electric Power Co plans to fill a leaking reactor at the Fukushima Daiichi power plant with sea water to cool it down and reduce pressure in the unit, Japan's top government spokesman said on Saturday.

"The nuclear reactor is surrounded by a steel reactor container, which is then surrounded by a concrete building," Chief Cabinet Secretary Yukio Edano said.

"The concrete building collapsed. We found out that the reactor container inside didn't explode."

Japan earlier in the day warned of a meltdown at the reactor at the plant, damaged when a massive earthquake and tsunami struck the northeast coast, but said the risk of radiation contamination was small.

"We've confirmed that the reactor container was not damaged. The explosion didn't occur inside the reactor container. As such there was no large amount of radiation leakage outside," he said.

"At this point, there has been no major change to the level of radiation leakage outside (from before and after the explosion), so we'd like everyone to respond calmly," Edano said.

"We've decided to fill the reactor container with sea water. Trade minister Kaieda has instructed us to do so. By doing this, we will use boric acid to prevent criticality."

Edano said it would take about five to 10 hours to fill the reactor core with sea water and around 10 days to complete the process.

Edano said due to the falling level of cooling water, hydrogen was generated and that leaked to the space between the building and the container and the explosion happened when the hydrogen mixed with oxygen there.

New York Times - Explosion not at reactor 2011 03 12 0745 EST

WASHINGTON - An explosion at a nuclear power plant in northern Japan on Saturday blew the roof off one building, brought down walls and caused a radiation leak of unspecified proportions, Japanese officials said, after Friday's huge earthquake caused critical failures in the plant's cooling system.

Yukio Edano, confirmed earlier news reports of an explosion at the Fukushima Daiichi nuclear plant, 15o miles north of Tokyo, saying: "We are looking into the cause and the situation and we'll make that public when we have further information."

* * *

Naoto Sekimura, a professor at Tokyo University, told NHK, Japan's public broadcaster, that "only a small portion of the fuel has been melted. But the plant is shut down already, and being cooled down. Most of the fuel is contained in the plant case, so I would like to ask people to be calm."

The plants' problems were described as serious but were far short of a catastrophic emergency like the partial core meltdown that occurred at the Three Mile Island plant near Harrisburg, Pa., in 1979.

NucNet - THE NUCLEAR COMMUNICATIONS NETWORK Japan Update / Brief No. 55 / 12th March 2011

Tepco Confirms Venting Of Unit 1, 'Reactor Not Affected' By Explosion

12 Mar (NucNet): Tokyo Electric Power Company (Tepco) has confirmed that it has successfully vented the containment of unit 1 at the Fukushima-Daiichi nuclear power plant in northern Japan.

Meanwhile, chief cabinet secretary Yukio Edano has told a press conference that there was an explosion at Fukushima-Daiichi at 15:36 local time, but he said it has not affected the reactor's primary system or its containment.

Mr Edano said there was a hydrogen explosion in the space between the concrete container and the reactor's primary system. However, the explosion did not damage the containment function or the reactor system, he added.

In a statement, Tepco said the venting of unit 1 had been successful and it was preparing to vent units 2 and 3, which also shut down automatically when the 8.9-magnitude earthquake hit yesterday.

The utility also confirmed that the national government had ordered an evacuation for residents within a 10 km radius of the plant's periphery.

Tepco has not yet made any comment on the explosion at the plant, although confirmation of successful venting would appear to contradict media reports that the containment has been breached.

Venting is designed to reduce pressure in the containment. It is not yet known why the pressure increased.

Earlier, Tepco said the pressure in unit-1's containment was 600 kilopascal (6 bar) and according to Japan's Nuclear and Industrial Safety Agency (NISA) it could have increased to 840 kilopascal (8.4 bar) in the meantime. NISA said the design pressure for the unit's containment is 400 kilopascal (4 bar).

Wire Services - Explosion, injuries reported at Fukushima 2011 03 12 | 0350 EST

TOKYO (Dow Jones)--An explosion was heard and white smoke was seen around the Fukushima Daiichi nuclear power plant late Saturday afternoon in Japan, though the cause and exact location of the event were not immediately clear, according to Japan's national broadcaster NHK.   Several people appeared to have been injured in the incident, NHK said.

Reuters - Japan Chief Cabinet Secretary Edano: expands evacuation area at no.2 plant to 10 km.

Bloomberg Reactor Fuel Rods May Have Started to Melt 2011 03 12 | 0345 EST

A nuclear reactor in the Fukushima Dai-Ichi power station about 220 kilometers (140 miles) north of Tokyo may be starting to melt down after Japan's biggest earthquake on record hit the area yesterday.

Fuel rods at the No. 1 reactor at the plant run by Tokyo Electric Power Co. may be melting after radioactive Cesium material left by atomic fission was detected near the site, Nuclear and Industrial Safety Agency, spokesman Yuji Kakizaki said by phone today.

"If the fuel rods are melting and this continues, a reactor meltdown is possible," Kakizaki said. A meltdown refers to a heat buildup in the core of such an intensity it melts the floor of the reactor containment housing.

Wall Street Journal - Japan Scrambles to Avert Meltdown - |2011 03 12 | 0252 EST

TOKYO-Emergency measures taken to avert a meltdown at a nuclear power plant hit by Friday's massive earthquake in northern Japan appear to be working, the plant's operator said after earlier warning that it faced a meltdown threat.

Workers are bringing down dangerous pressures that had built up in the container for the Fukushima Daiichi No. 1 nuclear reactor, a spokesman for Tokyo Electric Power Co. said Saturday afternoon.

"The steps we have taken through relieving the pressure inside the container and adding additional water to cool the rods appear to be succeeding in averting any damage to the reactor core, which was our main priority," said a Tepco spokesman.

Previously, the utility had said there was a risk of a meltdown in the core after the quake cut off power to pumps providing cooling water. That, in turn, could lead to heating of the core, the risk of a meltdown, and the release of radiation.

A portion of the reactor's fuel rods, which create heat through a nuclear reaction, had become exposed due to the cooling-system failure. The spokesman for Tepco said 1.5 meters of the 4.5 meter long fuel rods were exposed. It was unclear Saturday afternoon whether the water added by workers had re-covered the rods.

Loss of cooling water resulted in a near meltdown of the Three Mile Island reactor in Pennsylvania in 1979, the worst nuclear incident in U.S. history.

Asked about the impact of radiation at eight times higher than normal levels, Naoto Sekimura, a professor of quantum engineering at Tokyo University, said on national broadcaster NHK, "This is a minuscule amount. This is not going to have negative impact on the human body."

Later on Saturday, Tokyo Electric said another nuclear-power plant nearby, Fukushima Daini, was experiencing rises of pressure inside its four reactors. A state of emergency was called and precautionary evacuations ordered. The government has ordered the utility to release "potentially radioactive vapor" from the reactors, but hasn't confirmed any elevated radiation around the plant.

Start Saturday March 12, 2011 coverage

End Friday March 11, 2011 coverage

CNN - Two Japanese plants struggling to cool cores 2011 03 11 1730 EST

Tokyo (CNN) -- Reactors at two Japanese power plants can no longer cool radioactive substances inside, a prominent electric company said Saturday, according to a news agency report that added that atomic material may have leaked out of one of the plants.

Citing the Tokyo Electric Power Co., Japan's Kyodo News Agency said that radioactive substances may have seeped out of the Fukushima Daiichi nuclear reactors, about 160 miles (260 kilometers) north of Tokyo.

Potentially dangerous problems in cooling radioactive material appear to have cropped up there, as well as at another of the Tokyo Electric Power Company's nuclear plants. Both plants are named Fukushima Daiichi and both have nuclear reactors, but they are separate facilities.

Kyodo reported Saturday that the power company alerted authorities that the cooling system at three of the four units of one Fukushima Daini plant in northeastern Japan's Fukushima prefecture had failed.

LA Times - Japan nuclear plant conditions worsening 2011 03 11 1944 EST

The Kyodo news agency says the cooling system has failed at three reactors at a nuclear power plant in Fukushima Prefecture in northeastern Japan and that the coolant water's temperature has reached boiling level.

Conditions appear to be worsening at a nuclear power plant in Fukushima Prefecture in northeastern Japan, according to local media.

The Kyodo news agency reported that the cooling system has failed at three reactors of Fukushima No. 2 nuclear power plant. The coolant water's temperature had reached boiling temperature, the agency reported, citing the power plant's operator, Tokyo Electric Power.

The cooling system failure at the No. 2 power plant came after officials were already troubled by the failure of the emergency cooling system at the Fukushima No. 1 plant, which officials feared could cause a meltdown.

Associated Press State of Emergency declared for five reactors 2011 03 11 1815 EST

TOKYO - Japan declared states of emergency for five nuclear reactors at two power plants after the units lost cooling ability in the aftermath of Friday's powerful earthquake. Thousands of residents were evacuated as workers struggled to get the reactors under control to prevent meltdowns.

A single reactor in northeastern Japan had been the focus of much of the concern in the initial hours after the 8.9 magnitude quake, but the government declared new states of emergency at four other reactors in the area Saturday morning.

The earthquake knocked out power at the Fukushima Daiichi plant, and because a backup generator failed, the cooling system was unable to supply water to cool the 460-megawatt No. 1 reactor. Although a backup cooling system is being used, Japan's nuclear safety agency said pressure inside the reactor had risen to 1.5 times the level considered normal.

Authorities said radiation levels had jumped 1,000 times normal inside Unit 1 and were measured at eight times normal outside the plant. They expanded an earlier evacuation zone more than threefold, from 3 to 10 kilometers (2 miles to 6.2 miles). Some 3,000 people had been urged to leave their homes in the first announcement.

The utility, which also operates reactors at the nearby Fukushima Daini plant, later confirmed that cooling ability had been lost at three of four reactors there, as well as a second Fukushima Daiichi unit. The government promptly declared a state of emergency there as well.

Japan Nuclear and Industrial Safety Agency official Ryohei Shiomi said radiation levels surged inside the control center at the Fukushima Daiichi No. 1 reactor, while a monitoring device at the front gate of the compound detected radiation that is eight times higher than normal.

The level outside the 40-year-old plant in Onahama city, about 170 miles (270 kilometers) northeast of Tokyo, is still considered very low compared to the annual exposure limit, Shiomi said. It would take 70 days of standing at the gate to reach the limit, he said.

Shiomi said radioactive vapor probably entered the control room because of lack of air flow control resulting from power outage. The control room is usually radiation free, protected by negative air pressure. If the condition persists or worsens, the plant is equipped with gas masks and other protective gear to protect workers from radiation exposure, he said.

Officials planned to release slightly radioactive vapor from the unit to lower the pressure in an effort to protect it from a possible meltdown, but the continuing power supply problem has delayed the process.

Chief Cabinet Secretary Yukio Edano said the amount of radioactive element in the vapor would be "very small" and would not affect the environment or human health. "With evacuation in place and the ocean-bound wind, we can ensure the safety," he said at a televised news conference early Saturday.

USA Today - Japan declares emergency at 2nd nuclear plant 2011 03 11 1836 EST

Update at 6:36 p.m. ET: The Japanese government has declared a nuclear emergency at the Fukushima No. 2 power plant. An emergency also exists at plant No. 1.

The cooling system has failed for three reactors at the Fukushima No. 2 nuclear plant, about seven miles from its quake-crippled companion, the Tokyo Electrical Power Co. now says.

The utility, which operates both Fukushima plants, notified the government Saturday morning that the failsafe system at the No. 2 plant stopped working as the coolant water topped the boiling point, the Kyodo news service reports.

Update at 6:25 p.m. ET: Japan's nuclear safety agency is preparing to issue what Kyodo News called "an unprecedented order" directing the Tokyo Electric Power Co. to open a valve at the earthquake-crippled Fukushima No. 1 nuclear power plant to release pressure from a reactor that is in danger of overheating.

Original post: Radiation 1,000 times normal has been detected inside a crippled nuclear plant in northeastern Japan where utility managers have released potentially radioactive steam to reduce mounting reactor pressure, the Kyodo News service is reporting, citing the government's safety agency.

That suggests radioactivity could spread around Tokyo Electric Power's Fukushima No. 1 plant, where thousands of residents within a 6-miles were ordered to leave before dawn Saturda

Mobile generator in service at Fukushima-Daiichi NPP;

Tepco Considers Controlled Venting

12 Mar (NucNet): Tokyo Electric Power Company (Tepco) has installed a mobile power generation unit at its Fukushima-Daiichi nuclear power plant in an effort to ensure the function of essential pumps for cooling reactors that automatically shut down during an earthquake yesterday.

The back-up power is needed because the plant's cooling system failed when the earthquake caused a power outage and emergency diesel generators stopped working after less than an hour for an as yet unknown reason.

The utility said pressure in the containment of the oldest unit on the site, unit 1, which has been in commercial operation since 1970, has continued to increase.

At 00:00 local time, the pressure was 600 kilopascal (6 bar) and according to Japan's Nuclear and Industrial Safety Agency (NISA) it could have increased to 840 kilopascal (8.4 bar) in the meantime. NISA said the design pressure for the unit's containment is 400 kilopascal (4 bar).

At 04:00 local time Tepco said it had decided to implement measures to reduce the pressure in the reactor containment vessel "for those units that cannot confirm a certain level of water injection by the reactor core isolation cooling system".

Tepco is considering a controlled containment venting in order to avoid an uncontrolled rupture and damage to the containment itself.

Tepco said there has already been a leak of a small amount of radioactive substances.

Earlier, authorities in Fukushima prefecture evacuated residents living within three kilometres of the plant.

Japanese officials also told the International Atomic Energy Agency (IAEA) that pressure is increasing inside unit 1's containment and they have decided to vent the containment to lower the pressure. The controlled release will be filtered to retain most radioactive substances within the containment, the IAEA said.

Three reactors at the plant were operating at the time of the earthquake, and the water level in each of the reactor vessels remains above the fuel elements, according to Japanese authorities.

The Japan Atomic Industrial Forum (JAIF) said earlier today that unit 2 at the six-unit plant suffered a loss of feeding water for its cooling system, caused by the cut-off of power supply. JAIF said Tepco had earlier reported to NISA that two emergency diesel generators were out of order at Fukushima-Daiichi.

Eleven nuclear reactors in areas of Japan affected by today's earthquake have all shut down automatically and so far there have been no reports of radioactive release, the Ministry of Economic Trade and Industry (METI) has said.

The 11 nuclear units are in three northern prefectures: Miyagi, Fukushima and Ibaraki. The reactors that automatically shut down because of the quake are:

• All three units at the Onagawa plant;

• Units 1, 2 and 3 at the Fukushima-Daiichi plant (units 4, 5 and 6 were undergoing a scheduled inspection and already shut down);

• All four units at the Fukushima-Daini nuclear plant;

• Unit 1 at the single-unit Tokai plant.

Earlier, NISA said no damage to nuclear plants has been reported "at this stage" following the earthquake

The US Geological Survey said the quake struck at 14:46 local time and was magnitude 8.9 on the Richter scale. The epicentre was about 70 kilometres east of Honshu and the depth was about 24 km.

The epicentre was about 80 km east of the Onagawa nuclear site and about 150 km north-east of both Fukushima sites.

New York Times - Japan expands evacuation area 2011 03 11 1805 EST

Japanese officials early Saturday expanded the area around a crippled nuclear power plant subject to emergency evacuation, as radiation levels inside the facility were reported to have surged and operators struggled to keep the plant's cooling system operating on battery power.

A Japanese nuclear safety panel said radiation levels were 1,000 times above normal in a reactor control room after a huge quake damaged the plant's cooling system, and that some radiation - it was not clear how much - had seeped outside the plant. The elevated radiation reading was taken inside the control room of the No. 1 reactor of the Fukushima plant.

Prime Minister Naoto Kan said before boarding a helicopter to visit the plant that the government had expanded the evacuation area around the plant to a six-mile radius from a two-mile radius.

The nuclear plant, known formally as the Fukushima Daiichi Nuclear Power Station, was operating in an emergency, battery-powered cooling mode seventeen hours after the earthquake knocked out its two main sources of the electrical power needed for safe shutdown. But the International Atomic Energy Agency said that "mobile electricity supplies have arrived at the site" to keep the crisis at the crippled plant from worsening.

The Chief Cabinet Secretary of the Japanese government said the plant was releasing steam with a "very small" amount of radioactive material to relieve pressure in one reactor at the. The government had earlier declared an "atomic power emergency" to begin the evacuation, a difficult challenge in the midst of a natural catastrophe

With the steam-driven pump in operation, pressure valves on the reactor vessel would open automatically as pressure rose too high, or could be opened by operators. "It's not like they have a breach, there's no broken pipe venting steam," said Margaret E. Harding, a nuclear safety consultant, who managed a team at General Electric, the reactor's designer, that analyzed pressure build-up in reactor containments. "You're getting pops of release valves, for minutes, not hours, that take pressure back down." Some of the radioactive steam would condense back to liquid in the containment building, she said.

Bloomberg - damaged reactor may release radioactive steam 2011 03 11 1745 EST

Tokyo Electric Power Co. may vent radioactive vapor to reduce pressure at its nuclear reactor in Fukushima, Japan, after the nation's strongest earthquake on record caused power failures, Chief Cabinet Secretary Yukio Edano said.

Radioactive elements in the vapor from the Dai-Ichi No. 1 reactor wouldn't pose a threat to public health, Edano said at a press conference today in Tokyo. The plant, 210 kilometers (130 miles) north of Tokyo, lost power after the earthquake yesterday and about 5,800 residents near the plant were ordered to evacuate.

Wire services - San Onofre Officials Expect No Problems 2011 03 11 1507 EST

Officials at the San Onofre Nuclear Generating Station south of San Clemente said they do not expect any issues.

"The waves that could reach the Southern California coastline shortly after 8 a.m. (Pacific) today due to the 8.9 magnitude earthquake that struck Japan would pose no danger to the San Onofre Nuclear Generating Station," spokesman Gil Alexander said in a statement. "The plant's protective measures include a reinforced tsunami wall 30 feet above sea level."

Power plants along the U.S. West Coast were preparing themselves in light of the tsunami alert on Friday, after a massive earthquake off Japan.

PG&E Corp (PCG.N: Quote) said its Diablo Canyon nuclear power plant was operating normally and the reactors were designed to deal with any big wave that might reach California later Friday.

Meanwhile, Southern California Edison, a unit of Edison International (EIX.N: Quote) said workers at its San Onofre plant would be monitoring "unusual small waves" that were likely to hit the coast and that the plant was designed with a 30-feet tsunami protective wall.

Reuters - TEPCO's biggest nuke plant continue ops after quake 2011 03 11 1431 EST

(Reuters) - Japan's Tokyo Electric Power Co said operations at its biggest Kashiwazaki-Kariwa nuclear plant were continuing after a strong quake hit northern Japan on Saturday.

A strong earthquake aftershock with a preliminary magnitude of 6.6 struck northwestern Japan on Saturday, about half a day after massive 8.9 magnitude quake hit northeastern Japan.

Four nuclear units at the plant continued to operate, while the three remaining units were kept shut, a company official at the plant said.

New York Times - Emergency Declared at Japanese Nuclear Plant 2011 03 11 1355 EST

The Japanese government declared an "atomic power emergency" and evacuated thousands of residents living close to a nuclear plant in northern Japan after a major earthquake, but officials said there had been no radiation leak from the facility and that problems with its cooling system were not critical.

The plant is designed to shut down safely after an earthquake, but its emergency diesel generators, needed to run water pumps, were not working. American experts on reactors of the Fukushima design said, though, that technicians at the plant would have several hours to restore power before any significant damage resulted.

Japan's nuclear safety agency said pressure inside one of six boiling water reactors at the Fukushima Daiichi plant had risen to 1.5 times the level considered normal, according to The Associated Press. To reduce the pressure, slightly radioactive vapor would be released, the news agency said, but it was not immediately clear if it was going to be released into the containment building or the atmosphere. The agency said the radioactive element in the vapor would not affect human health.

At least two other Japanese nuclear plants also reported trouble, but there was no radiation leak at either of them, government officials said. A number of nuclear reactors around the hardest-hit area of the country were shut down, and Japanese news media said a fifth of the country's total nuclear generating capacity was offline because of the quake.

Associated Press - Fukushima Daiichi reactor cooling system update

Japan's nuclear safety agency said pressure inside one of six boiling water reactors at the Fukushima Daiichi plant had risen to 1.5 times the level considered normal. To reduce the pressure, slightly radioactive vapor may be released. The agency said the radioactive element in the vapor would not affect the environment or human health.

After the quake triggered a power outage, a backup generator also failed and the cooling system was unable to supply water to cool the 460-megawatt No. 1 reactor, though at least one backup cooling system is being used. The reactor core remains hot even after a shutdown.

The agency said plant workers are scrambling to restore cooling water supply at the plant but there is no prospect for immediate success.

Chief Cabinet Secretary Yukio Edano said the 40-year-old plant was not leaking radiation. The plant is in Onahama city, about 170 miles (270 kilometers) northeast of Tokyo.

If the outage in the cooling system persists, eventually radiation could leak out into the environment, and, in the worst case, could cause a reactor meltdown, a nuclear safety agency official said on condition of anonymity, citing sensitivity of the issue.

Another official at the nuclear safety agency, Yuji Kakizaki, said that plant workers were cooling the reactor with a secondary cooling system, which is not as effective as the regular cooling method.

Kakizaki said officials have confirmed that the emergency cooling system - the last-ditch cooling measure to prevent the reactor from the meltdown - is intact and could kick in if needed.

"That's as a last resort, and we have not reached that stage yet," Kakizaki added.

CNN - Japan struggling to 'cool down' nuclear plant, minister says 2011 03 11 1327 EST

U.S. President Barack Obama said Friday that Japanese Prime Minister Naoto Kan told him there was no evidence so far of radiation leaks from nuclear reactors due to the earthquake and tsunami, an assertion also made by Edano earlier in the day.

Yet Edano said the Fukushima Daiichi reactor "remains at a high temperature," because it "cannot cool down." The Kyodo agency reported Friday that the radiation level was rising in a turbine building at the plant.

Cham Gallas, a professor of disaster management at the University of Georgia, said that it wouldn't be surprising if reactors get "both thermally hot and radioactively hot" after the reactors were shut down.

"When they shut down reactors, it takes a long time for them to go down," said Dallas. "It does not necessarily mean radioactive material got out of the reactor."

While authorities are "bracing for the scenario," the minister said, "At this moment, there is no danger to the environment."

Fire broke out at a second facility, the Onagawa plant, but crews were able to put that fire out, according to the International Atomic Energy Agency.

Using Air Force planes, the U.S. government has sent over coolant for the Fukushima plant, said Secretary of State Hillary Clinton on Friday.

New York Times - Cooling system under control at Fukushima nuclear reactor 2011 03 11 1155 EST

An analyst with the World Nuclear Association, a major international nuclear power group, said that he understood fresh cool water was now being pumped into the cooling system at Fukushima, reducing the threat of a meltdown.

"We understand this situation is under control," the analyst said. The analyst said he understood that a back-up battery power system had been brought online after about an hour, and begun pumping water back into the cooling system, where the water level had been falling.

Reuters Cooling system under control at Japan's Fukushima nuclear reactor 2011 03 11 1058 EST

(Reuters) - The World Nuclear Association, the main nuclear industry body, said Friday that it understood the situation at Japan's Fukushima plant after a massive earthquake was under control, and water was being pumped into its cooling system.

"We understand this situation is under control," an analyst at the association told Reuters.

The Japanese government had declared an emergency situation around the plant as a precaution and evacuated residents, saying a cooling system was not working.

The analyst said he understood that a back-up battery power system had been brought online after about an hour, and begun pumping water back into the cooling system, where the water level had been falling.

Reuters - Calif nuclear plants operating normally, on Tsunami alert 2011 03 11 0817 EST

Precautions are routine, California nukes operating normally

Reuters) - PG&E Corp declared an "unusual event" at the Diablo Canyon nuclear power plant in California due to a tsunami warning, which is a normal operating procedure, a spokesman at the NRC told Reuters Friday.  The tsunami warning followed the massive earthquake and tsunami off the coast of Japan.

NRC spokesman Scott Burnell said there was nothing wrong with the plant, but a tsunami warning is something that requires the plant to issue an unusual event.

The same thing would happen if, for instance, there was a twister in the general area or an earthquake in Mexico. It merely puts plant workers on alert to prepare for the unusual.

Both reactors at Diablo Canyon were operating normally and at full capacity.  Burnell said the reactors were designed to deal with the big wave expected to reach California later Friday.

The NRC also said Edison International's San Onofre nuclear plant was monitoring the tsunami but was only under a tsunami watch.

Diablo is located in the middle of the Californian coast, about halfway between Los Angeles and San Francisco.  San Onofre is on the Southern California coast between Los Angeles and San Diego.

Daily Mail UK - Control rods in core, internal cooling expected at Fukushima No. 1 power plant run by the Tokyo Electric Power  2011 03 11 0853 EST

Professor Tim Abram, a nuclear fuel technology expert at Manchester University, said that as long as a reactor is shut down, it is considered 'benign' until bosses decide it is safe to be turned back on.

He said: 'All nuclear facilities are designed to withstand seismic events.

'The magnitude of the seismic event that they are designed to withstand varies from country to country.

'It's not done on a case of a particular point on the Richter scale, but instead on the basis of probability of earthquakes in particular countries. In somewhere like Japan, the probability will be much, much higher.'

The professor said although a failure in the cooling system of a nuclear power plant was 'unexpected', once a reactor is shut down, the heat levels plummet anyway.

He said: 'Reactors shut themselves down automatically when something called "ground acceleration" is registered at a certain point, which is usually quite small. It will instantly drop control rods into the core.'

At that stage, he said, the heat of a nuclear station drops dramatically in a matter of seconds, and within a couple of minutes, it is down to under five per cent of its normal temperature.

He added: 'That's a tiny, tiny percentage of the usual power output of the core.

'You still need to get rid of the decay heat, but the system is very capable of doing that.

CNN - Cooling system problems at Fukushima NPP 2011 03 11 0910 EST

(CNN) -- Workers at a nuclear power plant in north-central Japan are having trouble cooling the reactor and authorities have asked nearby residents to evacuate, Chief Cabinet Secretary Yukio Edano said at a news conference Friday.

The Fukushima Nuclear Power Plant was shut down after the earthquake that hit the country.

"This is a precautionary instruction for people to evacuate. There is no radioactive leakage at this moment outside of the facility," he said. "At this moment there is no danger posed to the environment."

Japan declared a state of atomic power emergency after the earthquake, the Kyodo News agency reported. The government is sending senior officials and a defense force team to the power plant, it said.

Edano said plant workers were having trouble generating sufficient electricity to pump water into the cooling system. They were using all available backup electricity, he said.

"The emergency shutdown has been conducted but the process of cooling down the reaction is currently not going as planned," he said.

NucNet - 11 Reactors shut down in Japan 2011 03 11 0817 EST

TOKYO, March 11 (Xinhua) -- Japanese Prime Minister Naoto Kan on Friday declared a state of atomic power emergency after an earthquake hit Japan's northeastern Honshu island, but he denied there are any radiation leaks.

Chief Cabinet Secretary Yukio Edano said some cooling functions were not working at the plant and one reactor cannot be cooled down.

Separately, a fire broke out at a nuclear power plant in Miyagi Prefecture following the massive quake. Tokyo Electric Power Co. said that the fire started detected at a building housing the turbine at its Onagawa plant but denied any radiation leaks.

According to the ministry, 11 nuclear reactors were automatically shut down at the Onagawa plant, Fukushima No. 1 and No. 2 plants and Tokai No. 2 plant.

Reuters - Japan working to fix reactor cooling systems 2011 03 11 0852 EST

(Reuters) - A cooling system for a nuclear reactor was not working after a powerful earthquake in Japan, prompting the government to declare an emergency situation as a precaution although it said there was no radioactive leakage at present.

Residents that live within a 3 km radius of Tokyo Electric Power's Fukushima Daiichi nuclear plant have been told to evacuate, Japan's Chief Cabinet Secretary Yukio Edano told a news conference.  The declaration of a state of emergency allows the government to mobilize people and equipment to respond to the earthquake.

TEPCO confirmed that water levels inside the reactors at its Fukushima-Daiichi nuclear plant were on a falling trend, but added it was working to maintain water levels to avert the exposure of nuclear fuel rods.

The company has been trying to restore power to its emergency power system so that it can add water to the inside of the reactors, a TEPCO spokesman said.

NY Times - Japan orders evacuation near nuclear power plant 0800 EST

TOKYO (AP) - Japan is issuing an evacuation order to thousands of residents near a nuclear power plant. Japan's nuclear safety agency says the evacuation order to more than 2,800 people followed the government's declaration at a nuclear power plant after its cooling system failed following a massive earthquake Friday. The agency says plant workers are currently scrambling to restore cooling water supply at the Fukushima No. 1 power plant. There was no prospect for an immediate success. The plant experienced a mechanical failure in the backup power generation system to supply water needed to cool the reactor.

Chief Cabinet Secretary Yukio Edano said that the plant was not in immediate danger of radiation leak.

Los Angeles Times - size of earthquake surprises seismologists 2011 03 11 0800 EST

The 8.9 magnitude earthquake is among the top 10 ever recorded and occurred on an irregular fault line where a smaller temblor would be expected.

The magnitude 8.9 earthquake that struck Friday off the coast of Japan "is going to be among the top 10 earthquakes recorded since we have had seismographs," said seismologist Susan Hough of the U.S. Geological Survey in Pasadena. "It's bigger than any known historic earthquake in Japan, and bigger than expectations for that area."

Geologists had expected the portion of the Ring of Fire that produced this quake to yield a temblor on the order of magnitude 8 or perhaps 8.5, she said. "Something as big as an 8.9 is a bit of a surprise."

A quake that big usually requires a long, relatively straight fault line that can rupture, such as those found in Peru and along the eastern coast of South America. Thursday's quake occurred in the Japan Trench, where the Pacific tectonic plate slides under the Japan plate.

Reuters - IAEA says no radiation leaks at affect Japan NPP 2011 03 11 0758 EST

Reuters) - Japan has told the U.N. nuclear wathchdog that a heightened state of alert has been declared at the Fukushima Daiichi nuclear power plant after Friday's major earthquake, the Vienna-based agency said.

The International Atomic Energy Agency (IAEA) said it had also been informed that the plant had been shut down and that no release of radiation had been detected.

Wall Street Journal: Japan issues emergency at nuclear plant 2011 03 11 0716 EST

TOKYO-The Japanese government issued an official emergency at one of the country's nuclear plants Friday after a massive earthquake automatically shut down its reactors and caused problems with its cooling system, but said there are currently no reports of radiation leakage.

Kyodo News - Japan declares nuclear emergency 2011 03 11 0800 EST

Japan declared a state of atomic power emergency after the country was hit by its largest-ever magnitude earthquake, while saying no radiation leaks have been detected at or near any nuclear power plants as of Friday evening.

The International Atomic Energy Agency is scrambling for details from contacts with Japan's industry ministry, while saying in a statement that at least four nuclear power plants ''closest to the quake have been safely shut down'' after the 2:46 p.m. quake with a magnitude 8.8.

According to the ministry, a total of 11 nuclear reactors were automatically shut down at the Onagawa plant, Fukushima No. 1 and No. 2 plants and Tokai No. 2 plant after the biggest-magnitude quake in the country's modern history.

Xinhua News Service - 11 reactors offline in Japan 2011 03 11 0740

TOKYO, March 11 (Xinhua) -- Japanese Prime Minister Naoto Kan on Friday declared a state of atomic power emergency after an earthquake hit Japan's northeastern Honshu island, but he denied there are any radiation leaks.

Chief Cabinet Secretary Yukio Edano said some cooling functions were not working at the plant and one reactor cannot be cooled down.

Separately, a fire broke out at a nuclear power plant in Miyagi Prefecture following the massive quake. Tokyo Electric Power Co. said that the fire started detected at a building housing the turbine at its Onagawa plant but denied any radiation leaks.

According to the ministry, 11 nuclear reactors were automatically shut down at the Onagawa plant, Fukushima No. 1 and No. 2 plants and Tokai No. 2 plant.

Nuclear Engineering News (UK) - Japan mobilizes emergency response 2011 03 11 0800 EST

Onagawa, Fukushima Daiichi, Fukushima Daini and Tokai nuclear power stations have automatically shut down following a magnitude 8.8 earthquake off the northeast coast of the largest island of Japan, Honshu.

All four operating plants on that coast have automatically shut down, or SCRAMmed, according to Japan Atomic Information Forum (JAIF). Higashidori 1, which is also located on Honshu's northeast coast, was shut down for a periodic inspection.

The earthquake struck at 2:45pm local time. A 6:45 pm local time report from the Japan Nuclear and Industrial Safety Agency contained more information of damage and other problems in a site-by-site report.

-A C02 fire has broken out at Onagawa nuclear power station.

-Utility TEPCO has requested the establishment of a nuclear emergency response programme for Fukushima Daiichi 1&3 and Fukushima Daini 1.

JAIF reported that Fukushima Daiichi 1, 2 and 3 automatically shut down; units 4, 5 and 6 were in maintenance outages. Fukushima Daini 1, 2, 3 and 4 automatically shut down.

JAIF has reported that TEPCO sent the emergency report because emergency diesel generators at the two sites are out of order. It also said that there have been no reports of radiation detected outside of the site.

Nuclear power stations at Hamaoka, Kashiwazaki-Kariwa and Tomari are continuing normal operation, according to JAIF.

World Nuclear News (London UK) - Plant by plant status report following 8.9 magnitude earthquake in Japan (see URL for individual NPP) 2011 03 11 0800 EST

Nuclear reactors appear to have shut down normally during today's massive earthquake in Japan. Official sources have no reports of radioactive release.

Tokyo Electric Power Company (Tepco) alerted safety regulators to a technical emergency in relation to Fukushima Daiichi nuclear power plant, at which some emergency diesel generators failed to start automatically. Nisa noted that emissions from the exhaust stack of the showed no increase in radioactivity.

Tohoku Electric Power Company has reported a fire in the non-nuclear turbine building of Onagawa 1. A minor fire burned in a non-nuclear service building of Tepco's Fukushima Daini 1 but this was extinguished within two hours.

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