• Title/Summary/Keyword: Nuclear safeguards

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

  • Sunil S. Chirayath;Heukjin Boo;Seung Min Woo
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3525-3534
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    • 2023

  • 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.

  • https://doi.org/10.1016/j.net.2023.06.010 인용 PDF

Feasibility study of spent fuel internal tomography (SFIT) for partial defect detection within PWR spent nuclear fuel

  • Hyung-Joo Choi;Hyojun Park;Bo-Wi Cheon;Hyun Joon Choi;Hakjae Lee;Yong Hyun Chung;Chul Hee Min
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2412-2420
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    • 2024

  • The International Atomic Energy Agency (IAEA) mandates safeguards to ensure non-proliferation of nuclear materials. Among inspection techniques used to detect partial defects within spent nuclear fuel (SNF), gamma emission tomography (GET) has been reported to be reliable for detection of partial defects on a pin-by-pin level. Conventional GET, however, is limited by low detection efficiency due to the high density of nuclear fuel rods and self-absorption. This paper proposes a new type of GET named Spent Fuel Internal Tomography (SFIT), which can acquire sinograms at the guide tube. The proposed device consists of the housing, shielding, C-shaped collimator, reflector, and gadolinium aluminum gallium garnet (GAGG) scintillator. For accurate attenuation correction, the source-distinguishable range of the SFIT device was determined using MC simulation to the region away from the proposed device to the second layer. For enhanced inspection accuracy, a proposed specific source-discrimination algorithm was applied. With this, the SFIT device successfully distinguished all source locations. The comparison of images of the existing and proposed inspection methods showed that the proposed method, having successfully distinguished all sources, afforded a 150 % inspection accuracy improvement.

  • https://doi.org/10.1016/j.net.2024.01.054 인용 PDF

Lab scale electrochemical codeposition experiments for comparison to computational predictions

  • Lafreniere, Philip;Zhang, Chao;Simpson, Michael;Blandford, Edward D.
    • Nuclear Engineering and Technology
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    • v.52 no.9
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    • pp.2025-2033
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    • 2020

  • Signature-based safeguards (SBS) is being developed to assist tradition nuclear material accountancy methods in tracking material in pyroprocessing facilities. SBS involves identifying off-normal scenarios that would result in improper movement of material in a pyroprocessing facilities and determining associated sensor response signatures. SBS investigations are undertaken in the computational space utilizing an electrochemical transport code known as enhanced REFIN with anodic dissolution (ERAD) to calculate the affect of off-normal conditions in the electrorefiner (ER) on material movement. Work is undertaken to experimentally validate the predictions and assumptions made by ERAD for off-normal occurrences. These experiments were undertaken on a benchtop scale and involved operating an electrochemical cell at 10 separate current densities for constant current operations to deposit U and Gd at a W cathode. These experiments were then modeled using ERAD to compare calculated predictions versus analytical experimental results it was found. It was discovered both the experimental and calculated results reflect a trend of increased codeposition of U and Gd with increasing current density. ERAD was thus demonstrated to be useful for predicting trends from anomalous operation but will require further optimization to be utilized as a quantitative design tool.

  • https://doi.org/10.1016/j.net.2020.02.005 인용 PDF KSCI