Fission Product Inventory and Burnup Evaluation by Gamma Spectrometry of the AGR-2 Irradiation

Technical Report · Wed Jan 15 04:00:00 EST 2020

DOI:https://doi.org/10.2172/1599397· OSTI ID:1599397

Harp, Jason M. ^[1]; Stempien, John D. ^[1]; Demkowicz, Paul A. ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

Gamma spectrometry has been used to evaluate the burnup and fission product inventory of different components from the U.S. Advanced Gas Reactor (AGR) Fuel Development and Qualification Program’s second tristructural isotropic (TRISO)-coated particle fuel irradiation test (AGR-2). TRISO fuel in this irradiation included both uranium carbide/uranium oxide (UCO) kernels and uranium oxide (UO₂) kernels. Four of the 6 capsules contained fuel from the U.S. AGR program, and only those capsules will be discussed in this work. The inventories of gamma-emitting fission products from the fuel compacts and graphite compact holders were evaluated. These data were used to estimate the fractional release of fission products such as Cs-137, Cs-134, Eu-154, Ce-144, and Ag-110m from the compacts. The fraction of Ag-110m retained in the compacts ranged from approximately 2% of the calculated inventory to approximately full retention. Additionally, the activities of the radioactive cesium isotopes (Cs-134 and Cs-137) have been used to evaluate the burnup of all U.S. TRISO fuel compacts in the irradiation. The experimental burnup evaluations compare favorably with burnups calculated from physics simulations. Calculated burnups for UCO compacts range from 7.26 to 13.15 % fissions per initial metal atom (FIMA) and 9.01 to 10.69 % FIMA for UO₂ compacts. Measured burnup ranged from 7.3 to 13.1 % FIMA for UCO compacts and 8.5 to 10.6 % FIMA for UO₂ compacts. Results from gamma emission computed tomography performed on the graphite holders that reveal the distribution of different fission products in a component will also be discussed. Gamma tomography of graphite holders was also used to locate the position of compacts with TRISO fuel particles suspected of having silicon carbide layer failures that lead to in-pile cesium release.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: DOE Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1599397
• Report Number(s): INL/EXT--16-39777-Rev001
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
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TRISO