Godiva IV central cavity neutron environment characterization with threshold neutron detectors

Journal Article · 10 November 2024 · EPJ Web of Conferences (Online)

DOI: https://doi.org/10.1051/epjconf/202430806005 · OSTI ID:2478630

Whitman, Nicholas ^[1]; Pierson, Bruce ^[2]; Weldon, Robert ^[1]; Cutler, Theresa ^[1]; Gooden, Matthew ^[1]; Hutchinson, Jesson ^[1]; Sanchez, Rene ^[1]; Grove, Travis ^[1]; Goda, Joetta ^[1]

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1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Godiva IV is a cylindrical fast burst reactor comprised of approximately 65 kg of highly enriched uranium that is operated by Los Alamos National Laboratory and sited at the National Criticality Experiments Research Center at the Nevada National Security Site in Nevada in the United States. Godiva IV is typically operated at delayed critical and in the regime spanning from sub-prompt to super-prompt bursts. Godiva IV is used for sample irradiations, criticality safety demonstrations, dosimetry studies, and for studying super-prompt behavior. In preparation for both an upcoming experiment to reduce uncertainties in the prompt fission spectrum for ²³⁵U using threshold neutron detectors, and for future research using Godiva IV, it was desired to exercise the process of the selection of threshold neutron detectors/activation foils, radiation metrology, and the subsequent adjustment of the neutron spectrum. For this exercise, nine high purity threshold neutron detectors/activation foils were irradiated in a Godiva IV burst. The foils were then analyzed using a high-purity germanium detector in the NCERC counting laboratory to determine end of irradiation specific activities for available IRDFF-II reactions. This work summarizes the Godiva IV foil irradiation, radiation metrology results, and adjusted neutron spectrum. The results of this exercise ultimately characterized the neutron environment inside the sample irradiation cavity inside Godiva IV to a higher degree than previously performed, informed decisions for the upcoming larger scale experiment, and will inform future neutron spectrum characterizations at NCERC.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 2478630
• Report Number(s): LA-UR--23-24564
• Journal Information: EPJ Web of Conferences (Online), Journal Name: EPJ Web of Conferences (Online) Vol. 308; ISSN 2100-014X
• Publisher: EDP SciencesCopyright Statement
• Country of Publication: United States
• Language: English