Modeling demand rate and imperfect proof-test and analysis of their effect on system safety

Quantitative safety assessment of a safety system plays an important role in comparing design alternatives at design stage and deciding appropriate design options to apply for safety systems. There are a number of such indices given in the literature. Most of the safety indices consider only system parameters (hazard rate, repair rate, diagnosis, coverage, etc.) along with proof-tests (or inspection). This paper extends the underlying model to incorporate demand rate and imperfect proof-tests. It also introduces a new safety index, average probability of failure on actual demand (PFaD), and an availability index, manifested availability (mAv).This paper uses Markov regenerative process-based analysis for state probabilities. Based on state-probability values of various states of the underlying Markov chain, solutions are derived for safety index PFaD and availability mAv.