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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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Fusion Science and Technology
Latest News
NRC nominee Nieh commits to independent safety mission
During a Senate Environment and Public Works Committee hearing today, Ho Nieh, President Donald Trump’s nominee to serve as a commissioner at the Nuclear Regulatory Commission, was urged to maintain the agency’s independence regardless of political pressure from the Trump administration.
R. Pampin, A. Cubi, N. Taylor, M. Fabbri, P. Martinez-Albertos, P. Sauvan, Y. LeTonqueze
Fusion Science and Technology | Volume 80 | Number 8 | November 2024 | Pages 1012-1023
Research Article | doi.org/10.1080/15361055.2023.2278375
Articles are hosted by Taylor and Francis Online.
Photoneutrons may be generated in beryllium by energetic gamma rays via the reaction 9Be(γ,n)8Be. In ITER, the beryllium layer of the first wall may be the source of such photoneutrons. During plasma operation, these are of insignificant intensity compared with D-T neutrons from the plasma, but after shutdown, photoneutrons produced by decay gammas from neutron-activated material may be significant enough to impact sensitive electronic components in diagnostic or remote handling equipment that would not otherwise be exposed to neutrons.
Studies have been performed to characterize the expected photoneutron source and to evaluate the fluxes arising in detailed three-dimensional models of the ITER tokamak. The results show photoneutron fluxes approaching 105 n/cm2·s within the vessel and up to 103 n/cm2·s elsewhere within the bioshield 14 days after shutdown. When first-wall panels are being transported to the Hot Cell Facility after irradiation, a photoneutron flux exceeding 104 n/cm2·s within the transfer cask is predicted 21 days after shutdown. The peak values in the surrounding building are between 102 and 103 n/cm2·s at the same time.