Weibull 매개변수 계산 방법 및 평가 변수에 따른 흑연 노심 구조물의 설계평가 민감도 분석

Graphite, used in core components such as moderators and reflectors, is brittle and has variation in strength due to inherent defects such as pores and cracks. ASME Boiler and Pressure Vessel Code (ASME BPVC), Section III, Division 5, HHA-3200 provides design evaluation procedures for graphite core components, considering the distinct characteristics of graphite. The design evaluation procedures consist of simplified and full assessment procedures with material strength based on a Weibull distribution considering confidence interval. However, the ASME BPVC method for calculating Weibull parameters includes some unclear procedures, and studies on sensitivity analysis of major evaluation parameters are insufficient. Therefore, in this study, a Weibull parameter calculation method is proposed, and sensitivity analysis of evaluation results based on major evaluation parameters is performed. To minimize human error and conduct efficient evaluation, the design evaluation procedures are computerized. The evaluation is performed based on the proposed Weibull parameter calculation methods, and the results are analyzed. In addition, the probability of failure trends are analyzed for major evaluation parameters such as volume and maximum equivalent stress.