Development of a PFM code for evaluating reliability of pressure components subject to transient loading Original Research Article

In order to improve the PFM methodology and to evaluate the reliability and integrity of an aged RPV, the PFM code PASCAL is being developed. This code evaluates the conditional probability of crack initiation and fracture of pressure components subject to a transient loading based on Monte Carlo simulation. In addition to the common functions established in existing codes, the code has some original functions and features in the elasto-plastic fracture criterion based R6 method, the simulation models for the semi-elliptical crack extension and the effect of thermal annealing, improvement in Monte Carlo simulation and so on. This paper describes the main features of the code, the results of verification analysis and case studies on influence parameters by using above functions. The verification analysis and case studies are carried based on NRC/EPRI PTS benchmark problem. The basic performance of the code was verified by comparing the results with those by existing codes. From the result of case studies, the effectiveness and performance of main functions are examined and the influence of some parameters, such as fracture criterion, WPS, semi-elliptical crack extension models, existence of overlay clad, initial aspect ratio on the failure probability are also discussed.