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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.
Earl J. Schulz, John C. Lee
Nuclear Science and Engineering | Volume 73 | Number 2 | February 1980 | Pages 140-152
Technical Paper | doi.org/10.13182/NSE80-A18694
Articles are hosted by Taylor and Francis Online.
Time-optimal control of axial xenon oscillations in pressurized water reactors is investigated in the present study, properly accounting for operating constraints on the allowable axial offset (AO) band. The system equation describing the spatial xenon oscillations has been reformulated using a lambda mode expansion in a form that readily allows a physical interpretation of the state vector and the system equation. In particular, AO measurements can be used to define the entire system parameters completely. Previous optimal control studies have been limited to the case of controls to the origin in the xenon-iodine phase plane. Our present investigation indicates that time-optimal controls should, in general, involve bang-bang controls to a line segment in this phase plane, subject to a band constraint on allowable AO or available control strength. A suboptimal control strategy, which can be applied directly in actual operating conditions without the aid of on-line computers, is also proposed. Verification of the proposed time-optimal control strategies is performed through computer simulations of xenon-induced transients.