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- Solans, Virginie, et al.
(författare)
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Evaluating Peak Area Uncertainties in Connection to Passive Gamma Measurements of Spent Nuclear Fuel
- 2021
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Ingår i: Proceedings. - 9789295064355
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Konferensbidrag (refereegranskat)abstract
- In many countries, spent nuclear fuel is planned to be stored in a geological repository. Before the final encapsulation, safety parameters such as decay heat, criticality, and dose rate need to be ensured. A gamma scan of the spent nuclear fuel assemblies in the pool can extract valuable information needed to verify or update the declared values before the encapsulation. Gamma scans can be used to esti mate values such as burnup, cooling time, or initial enrichment [1], but also decay heat [2]. This paper presents results from a fullenergy peak area evaluation study of experimental gammaray spectra acquired from measurements using a highpurity germanium detector on 47 spent nuclear fuel assemblies from Sweden in 2016 and 2019. The assemblies chosen are UO2 fuel and represent a large span in cooling time, burnup, and initial enrichment [3]. The gamma spectra were acquired in the spent fuel pool of the Clab facility. As part of the measurement analysis, one wishes to determine the fullenergy net peak areas associated with selected fission products. This work presents results obtained using different methods to evaluate the fullenergy peak areas, including the use of different background estimations.In the determination of important safety parameters using gamma spectroscopy, it is crucial to consider uncertainties originating in the peak area analysis. The un certainty from the fullenergy peak area without the background has been evaluated and compared between the different models.
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- Solans, Virginie, et al.
(författare)
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Optimisation of used nuclear fuel canister loading using a neural network and genetic algorithm
- 2021
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Ingår i: Neural Computing & Applications. - : Springer Nature. - 0941-0643 .- 1433-3058. ; 33:23, s. 16627-16639
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an approach for the optimisation of geological disposal canister loadings, combining high resolution simulations of used nuclear fuel characteristics with an articial neural network and a genetic algorithm. The used nuclear fuels (produced in an open fuel cycle without reprocessing) considered in this work come from a Swiss Pressurised Water Reactor, taking into account their realistic lifetime in the reactor core and cooling periods, up to their disposal in the final geological repository. The case of 212 representative used nuclear fuel assemblies is analysed, assuming a loading of 4 fuel assemblies per canister, and optimizing two safety parameters: the fuel decay heat (DH) and the canister effective neutron multiplication factor keff. In the present approach, a neural network is trained as a surrogate model to evaluate the keff value to substitute the time-consuming-code Monte Carlo transport & depletion SERPENT for specific canister loading calculations. A genetic algorithm is then developed to optimise simultaneously the canister keff and DH values. The keff computed during the optimisation algorithm is using the previously developed artificial neural network. The optimisation algorithm allows (1) to minimize the number of canisters, given assumed limits for both DH and keff quantities and (2) to minimize DH and keff differences among canisters. This study represents a proof-of-principle of the neural network and genetic algorithm capabilities, and will be applied in the future to a larger number of cases.
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- Solans, Virginie, et al.
(författare)
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Spent Nuclear Fuel passive gamma analysis and reproducibility : Application to SKB-50 assemblies
- 2023
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Ingår i: Annals of Nuclear Energy. - : Elsevier. - 0306-4549 .- 1873-2100. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- This work studies the reproducibility of passive gamma spectroscopy measurements for spent nuclear fuels (SNFs). The fifty assemblies used for this study span over a variety of initial enrichments, burnups, and cooling times. These SNFs have been measured in two different gamma axial measurement campaigns. The net peak counts are determined for Cs-137, Eu-154 and Cs-134. Furthermore, a sensitivity analysis of the relative position of the SNF and the detector is performed. Most importantly, this work describes a methodology using an intrinsic self-calibration procedure that can be used to compare the relative activities of the radionuclides without the need for detailed knowledge about the measurement set-up and its properties. The reproducibility of the Cs-137 net peak count rate ranges between 2% and 4%. Systematic reproducibility of the ratio of Eu-154 and Cs-134 to Cs-137 is between 0,4% - 5 % using the intrinsic self-calibration method.
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