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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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Senate EPW Committee to hold Nieh nomination hearing
Nieh
The Senate Environment and Public Works Committee will hold a nomination hearing Wednesday for Ho Nieh, President Donald Trump’s nominee to serve as commission at the Nuclear Regulatory Commission.
Trump nominated Nieh on July 30 to serve as NRC commissioner the remainder of a term that will expire June 30, 2029, as Nuclear NewsWire previously reported.
Nieh has been vice president of regulatory affairs at Southern Nuclear since 2021, though since June 2024 he has been at the Institute of Nuclear Power Operations as a loaned executive.
A return to the NRC: If confirmed by the Senate, Nieh would be returning to the NRC after three previous stints totaling nearly 20 years.
Alain Hébert, Hadrien Leroyer
Nuclear Science and Engineering | Volume 176 | Number 3 | March 2014 | Pages 312-324
Technical Paper | doi.org/10.13182/NSE13-26
Articles are hosted by Taylor and Francis Online.
We investigate the OPTEX reflector model for obtaining few-group reflector parameters consistent with a reference power distribution in the core. The reference power distribution is obtained using a 142 872-region calculation defined over a two-dimensional eighth-of-core pressurized water reactor (PWR) and performed with the method of characteristics. The OPTEX method is based on generalized perturbation theory and uses an optimization algorithm known as parametric linear complementarity pivoting. The proposed model leads to few-group diffusion coefficients or P1-weighted macroscopic total cross sections that can be used to represent the reflector in full-core calculations. These few-group parameters can be spatially heterogeneous in order to correctly represent steel baffles and thermal shields present in modern PWRs. The optimal reflector parameters are compared with those obtained with a flux-volume weighting of the reflector cross sections recovered from the reference calculation. Important improvements in full-core power distribution are observed when the optimal parameters are used.