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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.
K. Natesan, D. L. Smith
Nuclear Technology | Volume 22 | Number 1 | April 1974 | Pages 138-150
Technical Paper | Fusion Reactor Materials / Material | doi.org/10.13182/NT74-A16283
Articles are hosted by Taylor and Francis Online.
Thermodynamic calculations were made on the distribution of hydrogen and tritium between various refractory metals and liquid lithium as a function of temperature. The limiting tritium pressures that can be attained by cold trapping secondary liquid metals such as sodium, potassium, and sodium—78 wt% potassium (NaK) were also calculated. In the absence of tritium breeding, these pressures are 2.5 × 10−5, 2 × 10−7, and 1.2 × 10−10 Torr for sodium, potassium, and NaK, respectively, which correspond to tritium concentrations in lithium of 45, 4, and < 1 ppm, respectively, at 700°C. For a 1000-MW(th) thermonuclear reactor with a tritium breeding rate of 150 g/day, a tritium recovery system that incorporates (a) a separate lithium purification loop with niobium as the permeable membrane, (b) NaK as the secondary heat transport fluid, and (c) tungsten cladding on the IHX tubes will yield a tritium pressure of 10−9 Torr or less in the secondary system. This configuration will result in a tritium release rate ∼10−6 g/h to the steam system for a tungsten-clad steam generator operating at ∼600°C. The corresponding activity release rate is ∼300 Ci/yr.