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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. Röllig
Nuclear Technology | Volume 35 | Number 2 | September 1977 | Pages 516-523
Fission Product Release | Coated Particle Fuel / Fuel | doi.org/10.13182/NT77-A31912
Articles are hosted by Taylor and Francis Online.
The release of the rare fission gases, krypton and xenon, from a high-temperature reactor pebble-bed core is predominantly determined by the heavy-metal contamination of the matrix material during manufacture. In the case of the Thorium High-Temperature Reactor prototype fuel, particles with failed coatings contribute <10% to the total core release of the xenon and krypton isotopes with the exception of long-lived 85Kr. In a series of irradiation experiments with spherical fuel elements, a linear relation between the gas release and the contamination of the matrix material was established. At mean fuel temperatures of 700°C (973 K), only ∼1% of the 85mKr and 133Xe produced by fuel contamination is released. The experimental data for the steady-state release of 13 krypton and xenon isotopes can be explained by describing the graphitic matrix material as a two-component. system. Component 1 is attributed to the graphitic grains of the raw material, and component 2 to the material between the grains, such as the amorphous, nongraphitized binder coke. The total contamination-induced release from the fuel elements is given by the retention characteristics of the two components working in parallel, followed in series by the gas-phase transport through the interconnected porosity of the fuel element structure. As a consequence of this model, the apparent activation energy for the steady-state release depends on the half-lives of the isotopes of the same species yielding, e.g., 5 kcal/mole (21 kJ/mole) for 140Xe and 9 kcal/mole (38 kJ/mole) for 138Xe.