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Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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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
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.
Hanlin Shu, Liangzhi Cao, Qingming He, Qi Zheng, Tao Dai
Nuclear Science and Engineering | Volume 198 | Number 11 | November 2024 | Pages 2209-2229
Research Article | doi.org/10.1080/00295639.2023.2295065
Articles are hosted by Taylor and Francis Online.
The unstructured mesh (UM)–based Monte Carlo (MC) method can utilize modern computer-aided-design/computer-aided-engineering platforms to obtain geometric models with reduced human effort and is capable of generating high-resolution tally data. This approach presents a significant advantage over the traditional Constructive Solid Geometry (CSG)–based MC method in handling complex geometries and conducting multiphysics calculations. In this study, the UM-based MC calculation capability was developed in the MC code NECP-MCX. On this basis, an automatic UM-based Consistent Adjoint-Driven Importance Sampling (CADIS) method was further studied and implemented in which the adjoint deterministic calculation, forward MC calculation, and variance reduction (VR) parameter generation were performed on the unified UM model. To achieve this, the discrete ordinates (SN)–Discontinuous Finite Element Method (DFEM) code NECP-SUN was embedded into NECP-MCX as the adjoint transport solver. Validations of the developed code and evaluations of the VR performance of the UM-based CADIS method were conducted on the Pool Critical Assembly (PCA) Replica benchmark and H. B. Robinson Unit 2 (HBR-2) benchmark. The numerical results indicated that the developed UM-based particle tracking capability achieved comparable accuracy to the CSG-based approach. Furthermore, compared to the traditional CADIS method, the UM-based CADIS method demonstrated higher figure-of-merit (FOM) values (3.5 to 44 times higher for the PCA Replica benchmark and 2.22 to 2.92 times higher for the HBR-2 benchmark), highlighting the superior VR performance of the UM-based CADIS method over the traditional CADIS method.
