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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.
Y. S. Rana, S. B. Degweker
Nuclear Science and Engineering | Volume 162 | Number 2 | June 2009 | Pages 117-133
Technical Papers | doi.org/10.13182/NSE08-13
Articles are hosted by Taylor and Francis Online.
In our earlier papers, we developed a theory of reactor noise for accelerator-driven systems (ADSs). It was shown that reactor noise in ADSs is different from that in critical or radioactive source-driven subcritical systems because of the periodically pulsed source and its non-Poisson character. Various noise descriptors, such as Rossi alpha, Feynman alpha (or variance to mean), power spectral density, and cross-power spectral density, were derived, for a periodically pulsed source, including correlation between different pulses and finite pulses of different shapes. Throughout the work we restricted ourselves to the case of prompt neutrons only. In the present paper, we extend the theory to the delayed neutron case. Feynman-alpha and Rossi-alpha formulas are derived by considering the source to be a periodically pulsed non-Poisson source, without correlations between different pulses. Each pulse is assumed to be a delta function. The calculations are carried out in the time domain that leads to closed-form expressions for these descriptors.