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Scientific paper

Hybrid Gamma Emission Tomography for the Verification of Unirradiated Fuel: A Viability Study

ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-Proliferation

Details

Identification
ISSN: 1977-5296, DOI: 10.3011/ESARDA.IJNSNP.2017.13
Publication date
1 December 2017
Author
Joint Research Centre

Description

Volume: 55, December 2017, pages 2-9,

Authors: E.A. Miller1, L.E. Smith1, V. Mozin2, R.S. Wittman1, L.W. Campbell1, M.A. Zalavadia1, N.S. Deshmukh1

1Pacific Northwest National Laboratory, 2Lawrence Livermore National Laboratory

Abstract:

Current International Atomic Energy Agency (IAEA) methodologies for the verification of fresh low-enriched uranium (LEU) and mixed oxide (MOX) fuel assemblies are volume-averaging methods that lack sensitivity to individual pins. Further, as unirradiated fuel assemblies become more and more complex (e.g., heavy gadolinium loading, high degrees of axial and radial variation in fissile concentration), the accuracy of current IAEA instruments degrades and measurement time increases. Particularly in light of the fact that no special tooling is required to remove individual pins from modern fuel assemblies, new capabilities for the verification of unirradiated (i.e., fresh LEU and MOX) assemblies are needed to ensure that fissile material has not been diverted. Passive gamma emission tomography has demonstrated potential to provide pin-level verification of spent fuel, but gamma-ray emission rates from unirradiated fuel emissions are significantly lower, precluding purely passive tomography methods. The work presented here introduces the concept of Hybrid Gamma Emission Tomography (HGET) for verification of unirradiated fuels, in which a neutron source is used to actively interrogate the fuel assembly and the resulting gamma-ray emissions are imaged using tomographic methods to provide pin-level verification of fissile material concentration. This paper describes the status of a viability study on the HGET concept, including: envisioned use-case scenarios and corresponding definitions of fuel assemblies; modeling framework based on Monte Carlo and deterministic transport methods, and its validation; quantitative assessment of candidate HGET signatures with a focus on prompt fission gamma rays and delayed fission gamma rays; a nominal HGETv1 instrument design; candidate HGET-specific tomographic reconstruction methods that fully incorporate declared information; and examples of simulation-based predictions of HGET performance.

Keywords: safeguards; fuel verification; gamma emission tomography

Reference guideline:

Miller, E.A., Smith, L.E., Mozin, V., Wittman, R.S., Campbell, L.W., Zalavadia, M.A., & Deshmukh, N.S. (2017). Hybrid Gamma Emission Tomography for the Verification of Unirradiated Fuel: A Viability Study. ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-proliferation, 55, 2-9. https://doi.org/10.3011/ ESARDA.IJNSNP.2017.13

THMB_Bulletin-55_p.2-9-Miller

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Hybrid Gamma Emission Tomography for the Verification of Unirradiated Fuel: A Viability Study
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