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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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The RAIN scale: A good intention that falls short
Radiation protection specialists agree that clear communication of radiation risks remains a vexing challenge that cannot be solved solely by finding new ways to convey technical information.
Earlier this year, an article in Nuclear News described a new radiation risk communication tool, known as the Radiation Index, or, RAIN (“Let it RAIN: A new approach to radiation communication,” NN, Jan. 2025, p. 36). The authors of the article created the RAIN scale to improve radiation risk communication to the general public who are not well-versed in important aspects of radiation exposures, including radiation dose quantities, units, and values; associated health consequences; and the benefits derived from radiation exposures.
Dandong Feng, Paolo Morra, Ramu Sundaram, Won-Jae Lee, Pradip Saha, Pavel Hejzlar, Mujid S. Kazimi
Nuclear Technology | Volume 160 | Number 1 | October 2007 | Pages 45-62
Technical Paper | Annular Fuel | doi.org/10.13182/NT07-A3883
Articles are hosted by Taylor and Francis Online.
This paper assesses the performance of internally and externally cooled annular fuel in a four-loop pressurized water reactor during a variety of transients and accidents, namely, the loss of flow accident (LOFA), main steam line break (MSLB), large break loss of coolant accident (LBLOCA), and rod ejection accident (REA). The RELAP5 code was the primary vehicle for these analyses, although the VIPRE code was also used to calculate the minimum departure from nucleate boiling ratio (MDNBR) for LOFA and MSLB transients based on the RELAP5 results. It has been found that the MDNBR for the annular fuel at 150% power was higher than the MDNBR value for the reference solid fuel at 100% power for LOFA and MSLB. For LBLOCA analysis, the RELAP5-3D code was applied twice since the code has a constraint on the reflood model, which can be applied to only one cooling surface (either the inner channel or the outer channel). The analysis, with the reflood model applied to the outer channel, showed that using the standard size (100%) accumulator but with an increased (150%) safety injection flow rate, the peak cladding temperature (PCT) for the annular fuel at 150% power would be ~1200 K (927°C). This is ~150°C higher than the PCT for the solid fuel at 100% power but 277°C lower than the regulatory limit of 1204°C. When the reflood model is applied to the inner channel, the PCT would be limited to 1100 K (827°C), which is only 50°C higher than the PCT for the solid fuel at 100% power and 377°C lower than the regulatory limit of 1204°C. The calculated fuel temperatures and enthalpies during the REA have been found to be much smaller for the annular fuel, even at 150% power, compared to that for the solid fuel at 100% power. These analyses indicate that the new internally and externally cooled annular fuel can accommodate 50% power uprate in a PWR and still maintain adequate safety margins for a variety of transients and accidents including LOFA, MSLB, LBLOCA, and REA.