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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.
Jae-Joo Ha, Tunc Aldemir
Nuclear Technology | Volume 79 | Number 3 | December 1987 | Pages 297-310
Technical Paper | Fission Reactor | doi.org/10.13182/NT87-A34019
Articles are hosted by Taylor and Francis Online.
An operational concern in natural-convection-cooled research reactors is pool-top 16N activity (PTNA). The conventional technique for reducing PTNA is to disperse the water plume rising above the core by a planar water jet and thus increase the transit time of 16N nuclei to the pool top. The extension in transit time is a function of pool dynamics under dispersion. Ideally, a sufficiently deep stagnant water layer is formed below the pool top to confine 16N activity to lower pool regions. The effects of changes in pool configuration and disperser design parameters on pool dynamics are not well known. These effects are important in determining the feasibility of a power upgrade without major facility modifications. Due to the complexity of pool geometry, pool dynamics under dispersion cannot be described by simple flow models. The COMMIX-1A code is used to simulate the pool dynamics of a typical natural-convection-cooled research reactor with plate-type elements as a function of pool configuration and disperser design parameters. The pool is partly described as continuum and partly as porous medium. All the major pool components are explicitly modeled. The differences between the shapes of some pool structures and computational cells are accounted for using the concept of directional surface permeability. The importance of local turbulence effects and cross-flow friction losses at the guide tubes above the core are also investigated. The results show the following: