A fatigue monitoring system in the nuclear power station. A fatigue evaluation on a pressure vessel of the Tsuruga No. 1 reactor using an automatic fatigue calculating system

For the Tsuruga Power Station No. 1 reactor, in order not only to evaluate a maintaining fatigue, but also to confirm at an actual reactor how actually forming fatigue is accumulated, and to what grade it was accumulated against its designed value, a fatigue monitoring system was mounted onto the reactor pressure vessel about ten years ago. This fatigue monitor can automatically and in real time collect its operation parameters to carry out automatically its fatigue calculation and also store these data. Then, by data output from this monitor, maintenance against fatigue evaluation of the design base can be proved and its long-term fatigue soundness can be forecast. And, recently, so-called 'environmental fatigue' where coolant environment in the reactor primary system reduces fatigue strength, has become a problem on discussion, and from this viewpoint, the monitor is thought to be an effective means to prove soundness of reactor. Here were introduced the fatigue monitor in the Tsuruga Power Station No. 1 reactor and its application results, evaluation of recorded fatigue coefficients, and so forth. (G.K.)