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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 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.
Rei Kimura, Kazuhito Asano
Nuclear Science and Engineering | Volume 194 | Number 3 | March 2020 | Pages 213-220
Technical Paper | doi.org/10.1080/00295639.2019.1685352
Articles are hosted by Taylor and Francis Online.
Nuclear energy has been one of the sustainable energy sources, but after the Fukushima Daiichi nuclear accident, large-scale light water reactors are losing price competitiveness due to the rising costs to meet elevated safety standards. On the other hand, small modular reactors (SMRs) have been developed by various teams and are expected to provide not only electricity but also heat for small communities, chemical plants, factories, mines, and hydrogen production. Since 2017, a multipurpose very small modular reactor (vSMR), namely, Mobile-Very-small reactor for Local Utility in X-mark (MoveluXTM), has been studied at Toshiba Energy Systems and Solutions Corporation as a feasible distributed energy source. The main concept to MoveluX is a heat pipe–cooled calcium hydride–moderated core to simplify the reactor system while increasing inherent safety and nuclear security. Portable vSMRs are useful for remote places; therefore, criticality safety during their transport is essential for vSMRs to gain popularity. In a previous paper, we discuss positive temperature reactivity coefficients of the hydride-moderated core and its control method. The phenomenon is caused by thermal-neutron spectrum shifts at increased temperatures. In the current paper, we show that a positive temperature reactivity coefficient can be utilized to maintain subcriticality during transport. The reactor core requires preheating to achieve criticality, which means the core does not become critical even though safety rods have been extracted in the low-temperature range. The positive reactivity in the low-temperature range establishes inherent criticality safety during transport of the reactor system.