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Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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Latest News
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.
Ding She, Zhihong Liu, Lei Shi
Nuclear Science and Engineering | Volume 185 | Number 2 | February 2017 | Pages 351-360
Technical Paper | doi.org/10.1080/00295639.2016.1272363
Articles are hosted by Taylor and Francis Online.
Dispersion fuel is used in high-temperature reactors (HTRs) and some other advanced reactors. It contains a stochastic mixture of microsphere fuel grains or burnable poison grains embedded in a matrix material, which leads to the so-called double heterogeneity problem in the neutron transport calculation. This work investigates an equivalent homogenization method to deal with the stochastic media. In this method, the stochastic media are transformed to a homogenized material by introducing spatial self-shielding factors and preserving first-collision probabilities. A transmission model is proposed to calculate the first-collision probabilities and the self-shielding factors. In addition, the method is extended to treat the stochastic media with multitype grains. The applicability and correction techniques for the proposed method are discussed. The proposed method has been implemented in a lattice physics code named XPZ for HTRs. Numerical results are presented for typical HTR fuel pebbles and are validated against Monte Carlo solutions. It is concluded that the proposed equivalent homogenization method is promising for treating the double-heterogeneity problem and can be conveniently implemented in existing lattice physics codes.