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NRC introduces microreactor regulatory framework
The Nuclear Regulatory Commission has released a new licensing framework for microreactors and similar reactor designs that may provide a more suitable pathway for applicants with simpler technologies.
The proposed rule—known as Part 57—is the latest to come out of the NRC’s rules review and overhaul stemming from the ADVANCE Act and 2025 nuclear-related executive orders. It is also the latest framework developed for advanced reactor designs shifting away from light water reactor technology, such as the Part 53 rule finalized in March.
Seongchan Kim, Han Gyu Joo
Nuclear Science and Engineering | Volume 197 | Number 8 | August 2023 | Pages 1564-1583
Technical papers from: PHYSOR 2022 | doi.org/10.1080/00295639.2022.2144083
Articles are hosted by Taylor and Francis Online.
The capability and performance of the hexagonal version of the nTRACER direct whole-core calculation code are enhanced for VVER applications by extending the geometry-handling features and also by implementing assemblywise parallelization of the planar method of characteristics (MOC) calculation with higher-order scattering. The geometry-handling methods for the VVER hexagonal geometry having various special constituents are presented with detailed illustrations. The assemblywise domain decomposition (ADD) scheme is established under the hexagonal coarse-mesh finite difference formulation, which is exploited to update the incoming angular flux needed for the ADD parallelization. The solution accuracy and parallel performance are assessed for various hexagonal core problems, including the VVER benchmarks. It is shown that the hexagonal geometry solutions of nTRACER match with the reference Monte Carlo solutions within about 50 pcm in reactivity and 1% in pin power distribution and that the hexagonal ADD can reduce the computing time of the planar MOC calculation by up to 53% when compared to the anglewise parallelization.