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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
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.
Samir M. Sami, C. H. Le
Nuclear Technology | Volume 77 | Number 1 | April 1987 | Pages 7-17
Technical Paper | Fission Reactor | doi.org/10.13182/NT87-A33947
Articles are hosted by Taylor and Francis Online.
A dynamic void quality perturbation model has been developed to improve the capabilities of the NUFREQ code with respect to local void perturbation calculations. The present model calculates the local void perturbation in terms of the local quality perturbation, the dynamic drift flux parameters, and the transient time. In addition, the model evaluates the void reactivity feedback and the boiling channel nuclear reactor feedback. Depending on the flow regime, this model can predict the local void fraction perturbation in horizontal (CANDU reactors) and vertical channels (light water reactors). Numerical results revealed that this model enhanced the capabilities of the NUFREQ code and improved its accuracy in predicting the lower natural frequency as well as the system frequency response at higher frequencies.
