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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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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.
J. L. Rempe, K. Y. Suh, F. B. Cheung, S. B. Kim
Nuclear Technology | Volume 161 | Number 3 | March 2008 | Pages 210-267
Technical Paper | Reactor Safety | doi.org/10.13182/NT08-A3924
Articles are hosted by Taylor and Francis Online.
In-vessel retention (IVR) of core melt is a key severe-accident-management strategy adopted by some operating nuclear power plants and proposed for some advanced light water reactors (LWRs). If there were inadequate cooling during a reactor accident, a significant amount of core material could become molten and relocate to the lower head of the reactor vessel, as happened in the Three Mile Island Unit 2 accident. If it is possible to ensure that the vessel head remains intact so that relocated core materials are retained within the vessel, the enhanced safety associated with these plants can reduce concerns about containment failure and associated risk. For example, the enhanced safety of the advanced 600 MW(electric) pressurized water reactor (AP600) designed by Westinghouse, which relied upon external reactor vessel cooling (ERVC) for IVR, resulted in the U.S. Nuclear Regulatory Commission approving the design without requiring that certain features common to existing LWRs, such as containment sprays, be safety related. Clearly, ERVC offers the potential to reduce the AP600's construction and operating costs. However, it is not clear that the ERVC proposed for the AP600 could provide sufficient heat removal for higher-power reactors [up to 1500 MW(electric)] without additional enhancements. This paper reviews efforts made and results reported regarding the enhancement of IVR in LWRs. Where appropriate, the paper identifies what additional data or analyses are needed to demonstrate that there is sufficient margin for successful IVR in high-power thermal reactors.