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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.
José N. Reyes Jr.
Nuclear Technology | Volume 210 | Number 5 | May 2024 | Pages 906-918
Research Article | doi.org/10.1080/00295450.2023.2264475
Articles are hosted by Taylor and Francis Online.
NuScale Power has completed a series of full-length helical coil steam generator tests at SIET Laboratories in Piacenza, Italy. The test program included an investigation of the onset and evolution of density wave oscillations (DWOs). This paper describes the mechanisms leading to the onset of DWOs. A semi-empirical DWO stability correlation was developed from first principles using data from tests performed in the full-height (2015) TF-2 counterflow test facility. This research supports the concept that the onset of DWOs is caused by liquid bridging inside the boiling length of the tubes. A DWO onset correlation is obtained by performing a steady-state momentum balance on the liquid slug created by liquid bridging in annular flow. This yields a momentum balance equation in terms of a set of dimensionless superficial velocities, a corresponding dimensionless pressure drop term, and an average void fraction. Envelope theory is then used to obtain a critical void fraction, which is substituted into the dimensionless momentum balance to obtain a DWO onset correlation similar to the Wallis countercurrent flooding correlation. Predictions using the DWO stability correlation have been compared to DWO experiments from the (2022) TF-2, TF-1, and Polimi. The predictions for the onset and termination of DWOs show excellent agreement with the data.