Evaluation of risk effective STIs with specific application to diesels

Abstract

From a risk standpoint, the objective of surveillance tests is to control the risk arising from failures which can occur while the component is on standby. At the same time, risks caused by the test from test-caused failures and test-caused degradations need also to be controlled. Risk-acceptable test intervals balance these risks in an attempt to achieve an acceptable low, overall risk. Risk and reliability approaches are presented which allow risk-acceptable test intervals to be determined for any component. To provide focus for the approaches, diesels are specifically evaluated, however, the approaches can be applied not only to diesels, but to any component with suitable data. Incorporation of the approaches in personal computer (PC) software is discussed, which can provide tools for the regulator or plant personnel for determining acceptable diesel test intervals for any plant specific or generic application. The FRANTIC III computer code was run to validate the approaches and to evaluate specific issues associated with determining risk effective test intervals for diesels. Using the approaches presented, diesel accident unavailability can be more effectively monitored and be controlled on a plant-specific or generic basis. Test intervals can be made more risk effective than they are now, producing more acceptable accident unavailabilities. The methods presented are one step toward performance-based technical specifications, which more directly control risks