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2025 ANS Annual Conference
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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
Sunming Qin, Benedikt Krohn, Victor Petrov, Annalisa Manera
Nuclear Technology | Volume 206 | Number 2 | February 2020 | Pages 307-321
Technical Paper | doi.org/10.1080/00295450.2019.1591155
Articles are hosted by Taylor and Francis Online.
Nonintrusive optical methods of flow visualization, like particle image velocity (PIV) and planar laser-induced fluorescence (PLIF), have been widely applied to obtain instantaneous velocity and concentration fields with high spatial and temporal resolutions. When there are density variances involved in the flow, however, the optical measurements become challenging. To prevent the laser sheet which is used to illuminate the flow from getting deflected due to the changes of densities, it is essential to match the refractive indices for the solutions used in the experiments. A methodology based on the mixing behavior of a ternary-component system is applied in this work and an index-matched density ratio of 3.16% has been obtained. To form a nonconfined round free jet, an experimental facility was designed with a jet nozzle diameter of 2 mm located at the bottom of a cubic tank with 30-cm side length. The jet flow is established by a servo-engine-driven piston to eliminate possible fluctuations introduced by the motor. A high-fidelity synchronized PIV/PLIF system was utilized to measure the velocity and concentration fields in the self-similar regions for the jet flow with density differences as well as for the reference cases in uniform environments. Results are analyzed and compared in terms of turbulent statistics. Important for validations of computational fluid dynamics simulations, turbulent eddy viscosity as well as turbulent diffusivity are computed according to the Boussinesq hypothesis and the standard gradient-diffusion hypothesis. Scalar transport has been characterized for the jet self-similar region compared with previous literature using pipe-shaped jet nozzle in terms of the decay constants, jet spreading rates, and virtual origins.