Validation of PSAs for use in risk-monitoring applications

The purpose of this paper is to examine the use of probabilistic safety assessment (PSA ) tools for evaluating the risk significance of changing plant configurations. The focus of this examination is the ability of current PSA technology to evaluate time-dependent variations in risk quantities. Recent results from the South Texas Project (STP) PSA are used to quantify the magnitude of changes in initiating event frequencies. Issues associated with interpreting the results of risk monitors are discussed.