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The transformation of the NRC: 50 years of commissioners
The dust is beginning to settle following the whirlwind of changes at the Nuclear Regulatory Commission over the past year, and 2025 ultimately may be viewed as a transformative year, as well as the year the NRC celebrated its golden anniversary. The 12 months of that milestone year brought more change to the agency in its composition, its mandate, and its relationship to the executive branch than any comparable period in the preceding four decades.
Now at 51 years and counting, the NRC is working with a full commission and issuing new rulemakings to both regulate and support the next round of nuclear deployments. With the turbulence of 2025 still fresh in our minds, Nuclear News decided it was a good time to revisit the professional backgrounds of all 42 NRC commissioners who have served over the agency’s 50-year history to see how the composition of the commission has evolved over time.
H. Guo, G. Martin, L. Buiron (CEA)
Proceedings | 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) | Charlotte, NC, April 8-11, 2018 | Pages 1231-1240
CEA is largely involved in the study of GEN-IV Sodium Fast Reactors (SFR). Some innovative reactivity control systems are proposed such as utilization of different absorbers or moderators materials, modification of absorber pin geometry, and application of burnable neutron poison. These designs possess potentials to improve its safety margin, economical performance or core characteristics while its complete analysis requires notably more accurate calculation of efficiency and evolution of isotopes’ concentrations under irradiation.
At the same time, the new determinist transport code APOLLO3® is under development at CEA and it will replace ERANOS code for fast reactors analysis. The scheme in APOLLO3® is constituted with two steps: sub-assembly calculation and core calculation with Multi-Parametric Output Library as connectors which enable the interpolation of cross-sections according to specific parameter. In this paper, each step and different cross-section scheme are detailed and validated by continuous energy Monte Carlo calculations. These results are also compared with determinist code system ERANOS.
Our works show high adaptability of TDT solver in APOLLO3® to complexes geometries and evolution of isotopes. With the ability of MINARET to treat unstructured mesh, the heterogeneous geometry, keeping absorber pins at core level calculation, improves significantly the calculation of control rods’ efficiency. APOLLO3® compute more accurately core’s reactivity variation with burn-up tabulated cross section scheme. Although variation of spatial self-shielding effect is very significant in absorber depletion, tabulated cross-sections scheme is able to bring this variation from sub-assembly calculation to core calculation. Hence, even homogeneous control rod description at core level shows accurate computation of reactivity variation.
Consequently, with development and validations, APOLLO3® shows improvement on SFR control rods neutronic simulation and analysis. With these new schemes presented in this paper, innovative reactivity control systems designs will be completely characterized and investigated in the near future.
