Fast reconstruction of Bayesian iterative approximation in passive gamma-ray tomography

Shiba, Shigeki; Sagara, Hiroshi

doi:10.1080/00223131.2019.1699192

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…Most authors have limited access to real measurement data, and therefore simulated data is often used. The IAEA has also released a PGET dataset measured with mockup fuel consisting of neutron-irradiated cobalt rods containing Co-60, and this mockup data has been used widely 8,9 .During 2021 and 2022, PGET measurement data was acquired at the Finnish nuclear power plants. A unique series of measurements was conducted on BWR (Boiling Water Reactor) fuel to test the ability of the PGET method to detect partial diversion also in the axial direction of the fuel.…”

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Improved Passive Gamma Emission Tomography image quality in the central region of spent nuclear fuel

Virta

Bubba

Moring

et al. 2022

Sci Rep

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Reliable non-destructive methods for verifying spent nuclear fuel are essential to draw credible nuclear safeguards conclusions from spent fuel. In Finland, spent fuel items are verified prior to the soon starting disposal in a geological repository with Passive Gamma Emission Tomography (PGET), a uniquely accurate method capable of rod-level detection of missing active material. The PGET device consists of two highly collimated detector banks, collecting gamma emission data from a 360° rotation around a fuel assembly. 2D cross-sectional activity and attenuation images are simultaneously computed. We present methods for improving reconstructed image quality in the central parts of the fuel. The results are based on data collected from 2017 to 2021 at the Finnish nuclear power plants with 10 fuel assembly types of varying characteristics, for example burnups from 5.7 to 55 GWd/tU and cooling times from 1.9 to 37 years. Data is acquired in different gamma energy windows, capturing the peaks of Cs-137 (at 662 keV) and Eu-154 (at 1274 keV), abundant isotopes in long-cooled spent nuclear fuel. Data from these gamma energy windows at well-chosen angles are used for higher-quality images, resulting in more accurate detection of empty rod positions. The method is shown to detect partial diversion of nuclear material also in the axial direction, demonstrated with a novel measurement series scanning over the edge of partial-length rods.

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Improved Passive Gamma Emission Tomography image quality in the central region of spent nuclear fuel

Virta

Bubba

Moring

et al. 2022

Sci Rep

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“…The PGET method has been studied extensively throughout the recent years, both with the help of simulated data 5 – 7 as well as with measured data from spent nuclear fuel 8 – 10 . The IAEA has previously released a set of PGET data from measurements of irradiated Co-60 rods, and this dataset has also been used widely 6 , 11 – 13 . The research on PGET data analysis and image reconstruction methods has led to major improvements in image quality and helped in building trust on the method for safeguards verification of spent nuclear fuel.…”

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In-air and in-water performance comparison of Passive Gamma Emission Tomography with activated Co-60 rods

Virta,

Bubba,

Moring

et al. 2023

Sci Rep

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A first-of-a-kind geological repository for spent nuclear fuel is being built in Finland and will soon start operations. To make sure all nuclear material stays in peaceful use, the fuel is measured with two complementary non-destructive methods to verify the integrity and the fissile content of the fuel prior to disposal. For pin-wise identification of active fuel material, a Passive Gamma Emission Tomography (PGET) device is used. Gamma radiation emitted by the fuel is assayed from 360 angles around the assembly with highly collimated CdZnTe detectors, and a 2D cross-sectional image is reconstructed from the data. At the encapsulation plant in Finland, there will be the possibility to measure in air. Since the performance of the method has only been studied in water, measurements with mock-up fuel were conducted at the Atominstitut in Vienna, Austria. Four different arrangements of activated Co-60 rods, steel rods and empty positions were investigated both in air and in water to confirm the functionality of the method. The measurement medium was not observed to affect the ability of the method to distinguish modified rod positions from filled rod positions. More extended conclusions about the method performance with real spent nuclear fuel cannot be drawn from the mock-up studies, since the gamma energies, activities, material attenuations and assembly dimensions are different, but full-scale measurements with spent nuclear fuel are planned for 2023.

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Iterative reconstruction algorithm comparison using Poisson noise distributed sinogram data in passive gamma emission tomography

Shiba

Sagara

2020

Journal of Nuclear Science and Technology

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Fast reconstruction of Bayesian iterative approximation in passive gamma-ray tomography

Cited by 3 publications

References 2 publications

Improved Passive Gamma Emission Tomography image quality in the central region of spent nuclear fuel

Improved Passive Gamma Emission Tomography image quality in the central region of spent nuclear fuel

In-air and in-water performance comparison of Passive Gamma Emission Tomography with activated Co-60 rods

Iterative reconstruction algorithm comparison using Poisson noise distributed sinogram data in passive gamma emission tomography

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