Verification of Probabilistic Fracture Mechanics Analysis Code for Reactor Pressure Vessel

Abstract

Nowadays, it has been recognized that probabilistic fracture mechanics (PFM) is a promising methodology in structural integrity assessments of aged pressure boundary components of nuclear power plants, because it can rationally represent the influencing parameters in their inherent probabilistic distributions without over conservativeness. A PFM analysis code PASCAL (PFM Analysis of Structural Components in Aging LWR) has been developed by the Japan Atomic Energy Agency to evaluate the through-wall cracking frequencies of domestic reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and pressurized thermal shock (PTS) transients. In addition, efforts have been made to strengthen the applicability of PASCAL to structural integrity assessments of domestic RPVs against non-ductile fracture. A series of activities has been performed to verify the applicability of PASCAL. As a part of the verification activities, a working group was established with seven organizations from industry, universities and institutes voluntarily participating as members. Through one year activities, the applicability of PASCAL for structural integrity assessments of domestic RPVs was confirmed with great confidence. This paper presents the details of the verification activities of the working group, including the verification plan, approaches and results.

Verification of probabilistic fracture mechanics analysis code PASCAL for reactor pressure vessel

“…It is also verified that CPI values calculated from PASCAL and Excel-based calculation tool are identical. These results together with our previous verification studies (Lu et al, 2020b;Li et al, 2021) show that the mathematical models and probabilistic calculation algorithms incorporated in PASCAL for Japanese PWR-type RPVs subjected to PTS transients work appropriately.…”

“…In previous verification studies performed in the PASCAL-WG, the analysis models and methods have been verified to be accurately incorporated into PASCAL (Li et al, 2021). Using PASCAL, PFM analyses for a Japanese PWR-type model RPV subjected to PTS transients were independently performed by participants, and the analysis results were confirmed to show a good agreement (Lu et al, 2020b).…”

“…The main purpose of the PASCAL-WG is to verify the analysis models and probabilistic calculation algorithms, and improve the applicability of PASCAL through step-by-step verification studies. In 2015, the source program of PASCAL was released to PASCAL-WG participants and its correctness of mathematical models and calculation algorithms has been checked (Li et al, 2021). In 2016 and 2017, using PASCAL, PFM analyses for a Japanese PWR-type model RPV subjected to PTS transients were independently performed by participants in the PASCAL-WG.…”