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NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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2025 ANS Annual Conference
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Chicago, IL|Chicago Marriott Downtown
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High-temperature plumbing and advanced reactors
The use of nuclear fission power and its role in impacting climate change is hotly debated. Fission advocates argue that short-term solutions would involve the rapid deployment of Gen III+ nuclear reactors, like Vogtle-3 and -4, while long-term climate change impact would rely on the creation and implementation of Gen IV reactors, “inherently safe” reactors that use passive laws of physics and chemistry rather than active controls such as valves and pumps to operate safely. While Gen IV reactors vary in many ways, one thing unites nearly all of them: the use of exotic, high-temperature coolants. These fluids, like molten salts and liquid metals, can enable reactor engineers to design much safer nuclear reactors—ultimately because the boiling point of each fluid is extremely high. Fluids that remain liquid over large temperature ranges can provide good heat transfer through many demanding conditions, all with minimal pressurization. Although the most apparent use for these fluids is advanced fission power, they have the potential to be applied to other power generation sources such as fusion, thermal storage, solar, or high-temperature process heat.1–3
Joseph L. Bottini, Caleb S. Brooks
Nuclear Technology | Volume 209 | Number 12 | December 2023 | Pages 1987-2001
Research Article | doi.org/10.1080/00295450.2022.2156244
Articles are hosted by Taylor and Francis Online.
The Two-Fluid Model (TFM) has long been the backbone of engineering-scale two-phase flow simulation in system-analysis codes and computational fluid dynamics codes. The classical TFM is limited in how it can capture the differences in the transport of small and large bubbles. The two-group TFM provides the ability to specify the unique transport characteristics of small and large bubbles separately. Expanding to two sets of conservation equations for the two bubble groups presents the additional challenge of bubble group accounting as bubbles can cross the group boundary. The three mass transfer terms in the two-group TFM are evaluated for flashing, condensing, and boiling flows using a partitioning method. The axial trends in the source terms are examined for these flow conditions with the available intergroup models. Two-group interphase models are implemented and evaluated against experimental data for flashing, condensing, and boiling flows with accurate two-group results. The capabilities of the two-group TFM are evaluated for these flow types, demonstrating the ability to predict two-group vapor properties without the need for flow regime transitions.
