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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
Argala Srivastava, Deep Bhandari, K. P. Singh, Umasankari Kannan
Nuclear Science and Engineering | Volume 197 | Number 4 | April 2023 | Pages 703-710
Technical Note | doi.org/10.1080/00295639.2022.2131343
Articles are hosted by Taylor and Francis Online.
In this technical note, an analysis of an integral experiment of the Advanced Heavy Water Reactor (AHWR) Critical Facility (CF) with a diffusion-based Monte Carlo (MC) method is discussed. In this method, the diffusion kernel is converted into probabilities per unit time for tracking the particle in the problem domain. The diffusion-based MC method is coupled with a time-dependent MC algorithm developed earlier and has been used for space-time simulations in neutron multiplication assemblies. Kinetics simulations are best solved using a transport MC route, but this requires long computational time. The diffusion-based MC method provides a faster solution in such space-time simulations. Most of the space-time kinetics studies and benchmarks are based on diffusion theory, and there are very few transport theory or MC benchmarks. Thus, the diffusion-based MC facilitates exact comparison with the large number of diffusion theory benchmarks. The efficacy of this method was tested earlier by comparison with the results of realistic space-time kinetics benchmarks based on diffusion theory methods involving multiregion reactors and detailed energy dependence. Comparison of our results with these benchmarks has shown satisfactory agreement.
As a step toward more detailed benchmarking, the ability and accuracy of this method are tested on the recent experiment done in the AHWR CF. The integral experiments with one thoria-based mixed oxide experimental fuel assembly in the core of the AHWR CF were analyzed with this method and were compared with the observed experimental values. The experiments consisted of measurement of the critical height and worth of shut-off rods (SORs) with the experimental fuel assembly placed at different lattice locations. Neutron count rates as a function of time after reactor trip for estimation of the worth of the SORs were also simulated, and the results are found to be in good agreement with the observed values.