Risk-Informed Assessment of the Technical Specifications of PWR RPS Instrumentation

A special Markov reliability model is used to simulate the effects of frequency of testing and allowable bypass time of the analog channels and logic trains on the performance of a pressurized water reactor, reactor protection system (RPS). The effects of these technical specifications (TSs) on the unavailability of the RPS and on the frequencies of spurious scrams, core damage, anticipated transients without scram, and large early releases are assessed. The use of these results to support decision making concerning changing the TSs in light of the relevant policy statement by the U.S. Nuclear Regulatory Commission on risk-informed decision making is demonstrated. The analysis includes point-value calculations sensitivity and uncertainty analysis.