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Investigations on the Pu-to-244Cm ratio method for Pu accountancy in pyroprocessing

  • Sunil S. Chirayath (Center for Nuclear Security Science and Policy Initiatives, Department of Nuclear Engineering, Texas A&M University) ;
  • Heukjin Boo (Department of Offensive Tactics, Army College) ;
  • Seung Min Woo (Department of Nuclear Engineering, Kyung Hee University)
  • Published : 2023.10.25

Abstract

Non-uniformity of Pu and Cm composition in used nuclear fuel was analyzed to determine its effect on Pu accountancy in pyroprocessing, while employing the Pu-to-244Cm ratio method. Burnup simulation of a typical pressurized water reactor fuel assembly, required for the analysis, was carried out using MCNP code. Used fuel nuclide composition, as a function of nine axial and two radial meshes, were evaluated. The axial variation of neutron flux and self-shielding effects were found to affect the uniformity of Pu and Cm compositions and in turn the Pu-to-244Cm ratio. However, the results of the study showed that these non-uniformities do not affect the use of Pu-to-244Cm ratio method for Pu accountancy, if the measurement samples are drawn from the voloxidized powder at the feed step of pyroprocessing. 'Material Unaccounted For' and its uncertainty estimates are also presented for a pyrprocessing facility to verify safeguards monitoring requirements of the IAEA.

Keywords

Acknowledgement

This research is part of Heukjin Boo's graduate study at Texas A&M University sponsored by the Republic of Korea Army. This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety(KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea. (No. 00239658). Authors would like to place on record their highest appreciation for the discussion with Ms. Kelley Holle Ragusa.

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