Performability study of a mission-critical system using reliability-analytic formalism

In this paper we present a performability study of the control rod mechanism in a nuclear reactor based on reliability analysis over reactor lifespan. The study uses a unified formalism framework that is applicable to various engineering disciplines. Study results reveal that mean reliability of the system degrades over time, as the uncertainty in the measurements increases. Results, also, show that reliability of the system is a function of the failure rate of the underlying system components; here as the failure rate values increase the system exhibits decreased levels of reliability. Results obtained are intuitive and consistent with those reported elsewhere in the literature. According to the study, the effect of incorporating redundancies was also investigated. Here, while one might envisage one single point of failure as a determining factor as to overall system performance, results show that introducing redundancies to other parts of the system does far better in as far as reliability issues are concerned. This is illustrated in the paper by means of redundancies introduced in different parts of the system under investigation. The results justify the fact that redundant linkages are not found in practice in the control rod mechanism of a nuclear reactor.