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NRC unveils Part 53 final rule
The Nuclear Regulatory Commission has finalized its new regulatory framework for advanced reactors that officials believe will accelerate, simplify, and reduce burdens in the new reactor licensing process.
The final rule arrives more than a year ahead of an end-of-2027 deadline set in the Nuclear Energy Innovation and Modernization Act (NEIMA), the 2019 law that formally directed the NRC to develop a new, technology-inclusive regulatory approach. The resulting rule—10 CFR Part 53, “Risk-Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors”—is commonly referred to as Part 53.
M. M. R. Williams
Nuclear Science and Engineering | Volume 199 | Number 7 | July 2025 | Pages 1107-1161
Research Article | doi.org/10.1080/00295639.2024.2444147
Articles are hosted by Taylor and Francis Online.
An extension of the work of Pázsit, Dykin, and Darby on multiplet evaluation has been made using a different method of solution and with the addition of an external reflecting material. The method of solution uses the scalar form of the transport equation to calculate the singlet, doublet, and triplet moments, and in the case when the source configuration requires it, the angular distribution can be obtained in terms of the scalar quantities by direct quadrature. The main contribution of this work is to demonstrate that the scalar approach is convenient, and if energy and anisotropic scattering are required, it is reasonably easy to make use of existing computer codes for solutions of the neutron transport equation. Also, it is shown that the addition of an external reflecting region can have a significant effect on the three multiplicity moments. Some numerical results are given to enable direct comparison to be made with other methods of solution.