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杉山 大輔*; 中林 亮*; 田中 真悟*; 駒 義和; 高畠 容子
Journal of Nuclear Science and Technology, 58(4), p.493 - 506, 2021/04
被引用回数:2 パーセンタイル:24.93(Nuclear Science & Technology)A modeling calculation methodology for estimating the radionuclide composition in the wastes generated at the Fukushima Daiichi nuclear power station has been upgraded by introducing an approach using Bayesian inference. The developed stochastic method describes the credible interval of the regression curve for the log-normal distribution of the measured transport ratio, which is used to calibrate the radionuclide transport parameters included in the modeling calculation. Consequently, the method can predict the robability distribution of the radionuclide composition in the Fukushima Daiichi wastes. The notable feature of the developed method is that it can explicitly investigate the improvement in the accuracy and confidence (degree of belief) of the estimation of the waste inventory using Bayesian inference. Specifically, the developed method can update and improve the degree of belief of the estimation of the radionuclide composition by visualizing the reduction in the width of uncertainty in the radionuclide transport parameters in the modeling calculation in accordance with the accumulation of analytically measured data. Further investigation is expected to improve the credibility of waste inventory estimation through iteration between modeling calculations and analytical measurements and to reduce excessive conservativeness in the estimated waste inventory dataset.
杉山 大輔*; 中林 亮*; 駒 義和; 高畠 容子; 塚本 政樹*
Journal of Nuclear Science and Technology, 56(9-10), p.881 - 890, 2019/09
被引用回数:4 パーセンタイル:37.41(Nuclear Science & Technology)A calculation methodology for estimating the radionuclide composition in the wastes generated at the F1NPS has been developed by constructing a skeleton overview of the distribution of radionuclides considering the material balance in the system and calculation flowcharts of the transportation of radionuclides into the wastes. The wastes have a distinctive feature that their level of contamination includes considerable uncertainties. The developed method can explicitly specify the intrinsic uncertainties as a band to be included in the estimated radionuclide composition and can quantitatively describe the uncertainties by calibration using data on actual waste samples. Further studies to improve the quality of the calculation method, and acquiring a quantitative understanding of the spatial distribution of radionuclides inside the reactor building are suggested to be important steps toward reasonable and sustainable waste management as an integral part of the decommissioning.