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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.
Weston M. Stacey, Jr.
Nuclear Science and Engineering | Volume 48 | Number 4 | August 1972 | Pages 444-458
Technical Paper | doi.org/10.13182/NSE72-A22512
Articles are hosted by Taylor and Francis Online.
A variational theory is developed for estimating reactivity worths (and other bilinear ratios) and reaction rate ratios in critical nuclear reactors. These estimates embody corrections to first-order perturbation theory which account for the flux change caused by the reactivity perturbation and for the changes in the flux and adjoint when the system is altered. The physical significance of certain generalized functions which arise in the development of the theory is investigated. The relation of the variational theory to generalized perturbation theory is examined, and the additional restrictions required to reduce the former to the latter are established. Finally, the variational theory is demonstrated to yield accurate estimates for reactivity worths and reaction rate ratios in a fast reactor model, subject to a wide range of alterations in nuclear properties and compositions.
