Development of a Statistical Method for Evaluation of Estimated Criticality Lower-Limit Multiplication Factor Depending on Uranium Enrichment and H/Uranium-235 Atomic Ratio

概要

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Errors associated with a criticality calculation method employed in safety evaluation of nuclear fuel cycle facilities should conservatively be estimated by utilizing calculation results of the method applied to criticality experiment systems that are required to be analogous to the facilities and reliable enough for benchmarking. The upper limit of the neutron multiplication factor of uranium and/or plutonium system that is judged to be sub-critical in consideration of calculation errors is called “estimated criticality lower-limit multiplication factor” (ECLLMF), and it should be determined by a statistical method. For benchmark results of criticality calculations depending on such parameters as uranium enrichment, H/235U atomic ratio and so on, an equation for determining the ECLLMF was derived by employing the statistical theories on the multiple regression analysis and non-central t-distribution. As an example, an application of the proposed formula was shown to the benchmark calculation results that were obtained for low-enriched homogeneous uranium systems with a combination of MVP II code and JENDL3.3 library.
一般社団法人日本原子力学会の論文
2007-02-25