Direct Measurement of U235 and Pu239 in Spent Fuel Rods with Gamma-Ray Mirrors

Technical Report · Mon Sep 30 04:00:00 EDT 2013

DOI:https://doi.org/10.2172/1328266· OSTI ID:1328266

Ziock, Klaus-Peter ^[1]; Alameda, J. B. ^[2]; Brejnholt, N. F. ^[2]; Decker, T. A. ^[2]; Descalle, M. A. ^[2]; Fernandez-Perea, M. ^[2]; Hill, R. M. ^[2]; Kisner, R. A. ^[1]; Melin, A. M. ^[1]; Patton, B. W. ^[2]; Ruz, J. ^[2]; Soufli, R. ^[2]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

The amounts of fissile Pu and U in spent nuclear fuel are of primary concern to the safeguards community. In particular, there are issues when safeguards transitions from an item accountancy basis (such as fuel bundles) to a fissile material mass basis as occurs when spent fuel enters a reprocessing plant. Discrepancies occur because item accountancy requires estimating the content of fissile material using indirect techniques such as the fuel burn-up and item-level measurements of radiation emissions from fission by-products. Direct measurement of the fissile content by monitoring line emissions from fissile species themselves is impossible because the lines are much weaker than those emitted by shorter-lived isotopes in the fuel. The goal of this project is to develop a technique to directly measure these weaker lines despite the presence of overwhelming radiation from other isotopes. This is achieved by using gamma-ray mirrors as a narrow band-pass filter. The mirrors reflect only energies of interest toward a HPGe detector that is shielded from direct view of the spent fuel and its fierce emissions. This can significantly improve the reliability with which the mass of fissile material is tracked.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1328266
• Report Number(s): ORNL/TM--2013/489; NN2001000; NNPORES
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION