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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.
R. C. Lloyd, R. A. Libby, E. D. Clayton
Nuclear Science and Engineering | Volume 82 | Number 3 | December 1982 | Pages 325-331
Technical Paper | doi.org/10.13182/NSE82-A19393
Articles are hosted by Taylor and Francis Online.
Experiments were performed with a 122-cm-diam sphere to determine criticality of aqueous solutions of plutonium in a system having low-neutron leakage. The plutonium in the chemical form of Pu(NO3)4 had a 240Pu content of 2.52 wt%. The critical-sphere concentration obtained in this experiment was analyzed along with data from eight additional critical experiments to evaluate the minimum critical concentration for plutonium. The limiting critical concentration was determined to be 7.62 g Pu/ℓ, for Pu(NO3)4 without excess acid and 7.59 g Pu/ℓ for a 239Pu-water mixture. From these data, the Maxwellian-averaged thermal value of the number of fission neutrons emitted per neutron absorbed by 239Pu, eta, was determined to be 2.056 ± 0.037. The value at 2200 m/s is 2.100 ±0.041.
