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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.
Donald J. Dudziak
Nuclear Science and Engineering | Volume 47 | Number 2 | February 1972 | Pages 230-234
Technical Note | doi.org/10.13182/NSE72-A22402
Articles are hosted by Taylor and Francis Online.
A derivation of the time-dependent forward stochastic equation is sketched for a point reactor with linear feedback and an arbitrary finite fission neutron frequency distribution. Certain pathological characteristics of possible stochastic trajectories are discussed, and limiting conjectures are made based on physical considerations. The time-independent forward stochastic equation with negative reactivity feedback is solved in the classical manner, leading to a recursion relation for the long-run probabilities. Next, all factorial moments of the long-run distribution are shown to be finite, and the corresponding probabilities, P(N,∞), are thus o(N-k) for any integer k. Following this, a more tractable recursion relation is presented for the simpler case of binary fission. For this simpler model, the equivalence to an independent analysis of the Kolmogorov forward matrix equations, as presented in a previous paper, is demonstrated. Finally, a simple recursion relation among factorial moments of the long-run distribution is derived for the binary fission model.