French Reactor Vessel Integrity

Abstract

The French fleet comprises 58 PWR. The integrity of the reactor pressure vessel is one of the main considerations regarding plant life extension. The limiting damage is the irradiation embrittlement associated with brittle fracture risk. During the operation, integrity assessment is updated every 10 years taking in account the knowledge acquired by the feedback. In addition steps have been taken to reduce irradiation. Moreover all the research and development have also led to improvements. The purpose of the paper, based on the latest updated demonstration of the 3 loops 900 MW vessels for the period 30–40 years of service, is to develop the strategy to be implemented to go beyond 40 years and the progress in each topic. On one hand the demonstration by analysis is the privileged axis of justification for an operating life of 60 years. - First, by improving at the maximum deterministic approach with regard to the input data and methods to reduce uncertainties. - Second, by a complementary probabilistic study with the aim of showing the conservatism of the deterministic approach. On the other hand, the arrangements already taken during operation for monitoring and mitigating irradiation embrittlement are maintened and reinforced: irradiation surveillance program, in service inspection, limitation and surveillance of fluence, not to mention heating the safety injection water which remains a possibility after the improvements of data and methods.