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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.
Sin Kim, Goon-Cherl Park
Nuclear Technology | Volume 117 | Number 3 | March 1997 | Pages 340-352
Technical Paper | Heat Transfer and Fluid Flow | doi.org/10.13182/NT97-A35348
Articles are hosted by Taylor and Francis Online.
The anisotropic turbulent diffusion and the turbulent mixing phenomena in rod bundle flow fields are studied. The former is a distinguishing feature of the flow through rod bundles, and the latter is essential to the subchannel thermal-hydraulic analysis. On the basis of the flow pulsation, which is suggested as a main process of turbulent mixing, scale relations for principal parameters such as the anisotropic factor and mixing rate are derived. To obtain a scale relation for the anisotropic factor, eddy viscosities are classified into isotropic and flow pulsation parts. Scales of each part are estimated using the scale analysis method. For the purpose of determining the length and velocity scales of the pul sating flow, a hypothetical circulating flow with a period corresponding to the frequency of the pulsation is assumed. The scale relation is compared with the experimental data and shows good agreement both with respect to trend and magnitude for various geometries. Thus, it is concluded that the flow pulsation is a significant contributor to the strong anisotropy in the rod bundle flow field. Also, the mixing rate is predicted by estimating the effective mixing velocity. The estimated mixing rate is transformed into well-known dimensionless numbers, which are compared with the experimental data and with correlations to verify the predictability.