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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.
Constantine P. Tzanos, Nelson A. Hanan, Achilles G. Adamantiades
Nuclear Technology | Volume 63 | Number 3 | December 1983 | Pages 369-396
Technical Paper | Nuclear Safety | doi.org/10.13182/NT83-A33266
Articles are hosted by Taylor and Francis Online.
A comparative assessment of the core degradation frequency due to internal accident initiators between a typical large liquid-metal fast breeder reactor (LMFBR) design and pressurized water reactors (PWRs) has been performed. For the PWR system, existing analyses have been utilized. For the reference LMFBR, an extensive analysis has been performed for two accident initiators, i.e., loss of off-site power and loss of main feedwater. Based on this analysis an estimate of ∼1 × 10-6/reactor·yr has been obtained for the core degradation frequency of the reference LMFBR. This estimate is significantly smaller than the PWR core degradation frequency (∼6 ×10-5/yr). A sensitivity analysis shows that the parameters having the largest impact on the unavailability of decay heat removal are (a) for the “loss of off-site power” initiator: human error and failure to restore off-site power, and (b) for the “loss of main feedwater” initiator: the leakage rates of the passive decay heat removal system and the adoption of the policy to repair the Na-NaK heat exchanger only during normal shutdowns. The results indicate that the LMFBR system has the potential of higher resistance than the PWR system to the accident initiators considered. The lower core degradation frequency estimated for the LMFBR system is due to the presence of two redundant and diverse reactor shutdown systems, with a self-actuated feature included in one of them, the incorporation of a passive decay heat removal system, and the significantly lower sensitivity of the reference LMFBR to primary system pipe breaks.
