https://doi.org/10.1140/epjs/s11734-025-01482-6
Regular Article
Space differencing to estimate the neutron energy spectrum in the bioshield region of a pressurized water reactor
1
Nuclear D&D Radwaste Research Center, KEPCO International Nuclear Graduate School, 45014, Ulsan, Republic of Korea
2
Department of NPP Engineering, KEPCO International Nuclear Graduate School, 45014, Ulsan, Republic of Korea
3
TBM Technology Team, Korea Institute of Fusion Energy, 34133, Daejeon, Republic of Korea
Received:
14
October
2024
Accepted:
20
January
2025
Published online:
5
February
2025
When we consider a permanent dismantling plan for nuclear power plants, radiological inventory should be evaluated. The radionuclide inventory depends on the neutron energy spectrum as well as the magnitude of the neutron flux. From the viewpoint of optimization of the trade-off between worker safety and economic efficiency, an excessively conservative approach is not desirable. In other words, a computational model is needed to obtain neutron energy spectrum set as realistically appropriate as possible. This study discusses numerical analysis techniques for radioactivity evaluation for pressurized water reactors to establish a realistic calculation system from the above-mentioned optimization perspective. First, through the theoretical review of the radiological inventory calculation procedure, we discuss the effect of neutron flux distribution and neutron energy spectrum on the calculation result of the radiation nuclide inventory. In this study, space differencing is investigated to determine any optimal calculation scheme for estimation of radioactivity. Considering the bioshield region of Kori unit 1, sensitivity of neutron energy spectrum is analyzed to resolution of space differencing. The results show that space differencing should be considered precisely to obtain an accurate effective cross section for an important nuclide, because variation of the neutron energy spectrum is not monotonic against the depth of bioshield. Based on the results from the case study on sensitivity of neutron energy spectrum, an optimal space differencing scheme could be determined.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
