10:30 AM - 10:45 AM
[3C01] Study of the Postulated Crack Size based on the Non-Destructive Inspection Results of the Reactor Vessel
Keywords:Reactor Vessel, License Renewal, Fatigue Crack Growth
The operation period of nuclear power plants in Japan is forty years. It may be extended for another twenty years after license renewal. For license renewal, it’s required to conduct special inspection and evaluation to prove its integrity for extended operation.
In the special inspection, ultrasonic inspection is conducted for beltline region of the reactor vessel to confirm the existence of the cracks. No cracks have been found in the special inspection. However, the possibility of minor cracks within detection limit cannot be eliminated.
In this study, minor crack is postulated to perform fatigue crack growth calculation, and crack size as of sixty years operation was confirmed to be smaller than crack size used in the plant life management evaluation.
In the special inspection, ultrasonic inspection is conducted for beltline region of the reactor vessel to confirm the existence of the cracks. No cracks have been found in the special inspection. However, the possibility of minor cracks within detection limit cannot be eliminated.
In this study, minor crack is postulated to perform fatigue crack growth calculation, and crack size as of sixty years operation was confirmed to be smaller than crack size used in the plant life management evaluation.