PFM Analysis of Embedded Crack in RPV

摘要

This paper describes a probabilistic fracture mechanics (PFM) analysis of aged nuclear reactor pressure vessel (RPV)rnmaterial. PFM approach is regarded as an appropriate method in rationally evaluating plant life and in risk-based decisionrnmaking such as risk-informed inspection, since it can consider various uncertainties such as sizes and distributions of cracks,rndegradation of material strength due to aging effects, fluctuating loading histories, accuracy and frequency of pre- and in-servicerninspections. Thus, various PFM computer programs have been developed and applied in practical situations in the last tworndecades. But the most programs can calculate only for surface cracks, because of the difficulty of evaluating fracturernparameters for embedded cracks, and the cost of computation.rnA new simulation program has been developed to solve PFM analysis of RPV with both elliptical embedded cracks andrnsemi-elliptical surface cracks. To demonstrate the effectiveness of the program, one of PFM round-robin problems set byrnJSME-RC111 committee, i.e. "aged RPV under normal and upset operating conditions" was solved. The effect of ignorancernof embedded cracks is also examined, and the availability of usual PFM codes, which ignore embedded cracks, is discussed.