BENCHMARKING STUDIES OF PROBABILISTIC FRACTURE-MECHANICS ANALYSIS CODE, PROFMAC-II, FOR ASSESSING PRESSURIZED THERMAL-SHOCK EVENTS OF REACTOR PRESSURE-VESSEL INTEGRITY ISSUES

The probabilistic fracture mechanics analysis code, PROFMAC-II, was de veloped and benchmarked for postulated pressurized thermal shock (PTS) events of pressurized water reactor pressure vessel integrity issues by participating the PTS benchmarking activities organized and managed jointly by U.S. Nuclear Regulatory Commission (USNRC) and Electric Po wer Research Institute (EPRI). Three different sets of benchmarking pr oblems were assigned to participants for the studies in sequence. The initial and second sets were preparatory to the third set. Results fro m the sequential benchmarking activities were that for axial flaw anal yses probabilities of crack initiation were identical to those for ves sel failure and the scatter of probabilities among four participating codes was small, while for circumferential flaw analyses probabilities varied widely. It was eventually verified that the same probabilities were achievable by unifying procedures for simulating material proper ties. Performance of the PROFMAC-II code was excellent in terms of con sistency and adequacy among the four codes and the eight organizations which took part in the studies. Several issues relevant to analysis t echniques and input variables were pointed out for further improvement of the codes.