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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Ho Nieh nominated to the NRC
Nieh
President Trump recently nominated Ho Nieh for the role of commissioner in the Nuclear Regulatory Commission through the remainder of a term that will expire June 30, 2029.
Nieh has been the vice president of regulatory affairs at Southern Nuclear since 2021, though he is currently working as a loaned executive at the Institute of Nuclear Power Operations, where he has been for more than a year.
Nieh’s experience: Nieh started his career at the Knolls Atomic Power Laboratory, where he worked primarily as a nuclear plant engineer and contributed as a civilian instructor in the U.S. Navy’s Nuclear Power Program.
From there, he joined the NRC in 1997 as a project engineer. In more than 19 years of service at the organization, he served in a variety of key leadership roles, including division director of Reactor Projects, division director of Inspection and Regional Support, and director of the Office of Nuclear Reactor Regulation.
Yukio Ishiguro, Keisuke Okumura
Nuclear Technology | Volume 84 | Number 3 | March 1989 | Pages 331-343
Technical Paper | Probabilistic Safety Assessment and Risk Management / Fission Reactor | doi.org/10.13182/NT89-A34217
Articles are hosted by Taylor and Francis Online.
A new concept is proposed for a high conversion light water reactor (HCL WR) that achieves both high conversion and high burnup while maintaining a negative void reactivity coefficient. This HCLWR has a flat “pancake” core with thick axial blankets. By using the flat core, a potential problem of HCLWRs, the positive void reactivity coefficient, can be reduced by neutron leakage, and a fuel assembly of very tight lattice pitch can be used. The leakage neutrons are utilized in the axial blankets to enhance the conversion ratio. With the axial blankets, the core shows a small value for the axial power peaking factor, and the plutonium enrichment can be largely reduced by the neutron reflection, including the fast fission due to 238U, compared with the bare core. Moreover, upgraded burnup characteristics can be obtained by the accumulation of fissile plutonium in the blankets. The flat core with the blankets can be applied to a small- or intermediate-scale light water reactor. The analysis combines a cell burnup calculation and a one-dimensional burnup calculation based on the diffusion method. The evaluation method of the void coefficient is validated for the flat core with axial blankets under practical, controlled conditions. Moreover, the accuracy of the present method is validated for the transport effect on the major physics parameters of interest by using the one-dimensional transport code ANISN and the Monte Carlo code VIM.
