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Udagawa, Makoto; Katsuyama, Jinya; Onizawa, Kunio
Proceedings of 10th International Workshop on the Integrity of Nuclear Components (ASINCO-10), p.219 - 226, 2014/04
A probabilistic fracture mechanics (PFM) analysis code PASCAL-NP has been improved continuously with reference to the latest knowledge. This code treats not only primary water stress corrosion cracking (PWSCC) in PWR but also Ni-based alloy stress corrosion cracking (NiSCC) in BWR. This code can also evaluate both leakage and break probabilities due to these types of SCC, considering the scatters of parameters which affect the structural integrity of Ni-based alloy welds. In this paper, failure probability analyses have been performed focusing on vessel head penetrations affected by PWSCC detected at Ohi unit 3 nuclear power plant as well as control rod drive housings affected by NiSCC at Hamaoka unit 1. In order to perform case studies for these actual plants, analytical models of predicting the incubation time to PWSCC and NiSCC initiation were introduced to PASCAL-NP. Failure probabilities calculated by PASCAL-NP reasonably agreed with inspection results in these plants.
Kanto, Yasuhiro*; Onizawa, Kunio; Osakabe, Kazuya*; Yoshimura, Shinobu*
Proceedings of 10th International Workshop on the Integrity of Nuclear Components (ASINCO-10), p.189 - 194, 2014/04
The international Round Robin (RR) activity was performed in PFM sub-committees in JWES in conjunction with Korea and Taiwan research groups. The purposes of this program were to establish reliable procedures to evaluate fracture probability of reactor pressure vessels during pressurized thermal shock and to maintain the continuous cooperation among Asian institutes in the probabilistic approach to nuclear safety. The results of this work were summarized at the previous ASINCO workshop in 2010. Here, as the phase 2 of the program, a new international round robin activity is planned. This paper describes the outline of the problem. The aims of the program and the matters to be noticed is presented.