Consideration on the experimental reliability determination, reliability improvements for nuclear reactor instrumentation

This paper describes the experimental tests performed in order to prove the reliability parameters for certain equipments manufactured in INR Pitesti, for NPP Cernavoda. The tests were provided by Technical Specifications and test procedures. The laboratory tests were performed in such running and environmental conditions that correspond to the real operating ones for the equipments under testing. A special attention was paid to the accelerated tests (intensive tests), where stress level applied is above the level established by reference condition (stated by design); the acceleration of the operating conditions in the sense of a time compressing may be considered, in the case of a product where it was stated that the reliability parameters depend mainly on the number of the operating cycles. A comparison, referring to the reliability parameters, between Canadian equipments and INR manufactured equipments is also given. On the other hand, there are presented reliability improvement measures taken in order to check that the equipments would operate within design specification. The results of tests and the conclusions are shown. I also mention that this paper is a partial layout of the results of the Research Contract with IAEA Vienna, completed at the end of 1991, where I have been Scientific leader. (author)