ANS flooding and seismic consensus standards assist the NRC and DOE in buttressing nuclear facility safety policies
April 2, 2021, 2:47PMNuclear NewsLeah Parks, Carl Mazzola, Jim Xu, and Brent Gutierrez A map of Japan highlighting the Fukushima prefecture.
March 11 will mark the 10-year anniversary of the Fukushima Daiichi event, when a 45-foot tsunami, caused by the 9.0-magnitude Great Tohoku Earthquake, significantly damaged the reactors at Japan’s Fukushima Daiichi nuclear power plant. In response to this event, the U.S. Nuclear Regulatory Commission took actions to evaluate and mitigate beyond-design-basis events, including a new requirement for the staging of so-called Flex equipment, as well as changes to containment venting and improvements to emergency preparedness. The U.S. Department of Energy also addressed beyond-design-basis events in its documented safety analyses.
The 40-year effort to make research reactors safer and more secure has led to the conversion of 71 reactors worldwide from HEU fuel to LEU.
The Ghana Research Reactor-1, located in Accra, Ghana, was converted from HEU fuel to LEU in 2017. Photo: Argonne National Laboratory
In late 2018, Nigeria’s sole operating nuclear research reactor, NIRR-1, switched to a safer uranium fuel. Coming just 18 months on the heels of a celebrated conversion in Ghana, the NIRR-1 reboot passed without much fanfare. However, the switch marked an important global milestone: NIRR-1 was the last of Africa’s 11 operating research reactors to run on high-enriched uranium fuel.
The 40-year effort to make research reactors safer and more secure by replacing HEU fuel with low-enriched uranium is marked by a succession of quiet but immeasurably significant milestones like these. Before Africa, a team of engineers from many organizations, including the U.S. Department of Energy’s Argonne National Laboratory, concluded its conversion work in South America and Australia. Worldwide, 71 reactors in nearly 40 countries have undergone conversions to LEU, defined as less than 20 percent uranium-235. Another 31 research reactors have been permanently shut down.