Support groups in operating organizations have established so-called ‘living PSA’ analysis systems with responsibility for daily updating of the plant operating and maintenance state, forward planning of scheduled mainte­nance operations, and contingency planning programs to predict the correct course of action for shift management personnel in the event of anticipated abnormal operating states. These incremental risk estimates are based on the latest updated version of the plant safety assessment.

A good example of this application to power plant operation is the soft­ware package named EOOS (Equipment Out Of Service), the risk and reliability workstation (EOOS Demo 3.5, 2008) produced by the Electric Power Research Institute (EPRI). EOOS is independent of other EPRI reliability analysis software such as the Cutset and Fault Tree Analysis (CAFTA) system (CAFTA, 2009) but uses many of the same conventions.

EOOS uses a safety or risk model of the plant, based on fault tress and minimal cutsets, such as those developed in a Probabilistic Risk Assessment (PRA). EOOS wraps a user-friendly interface around these reliability analysis tools to make them accessible to non-PSA experts.

EOOS communicates in the language of its users — using the familiar termi­nology of components, trains, systems, tests, and clearances. Using the current plant configuration, EOOS can propagate information through the model and quantify risk measures. EOOS translates fault tree results into color-coded status panels, timelines, and lists of relevant and risk-significant activities. Within seconds, an EOOS user can identify a safety problem, and the specific work activities that cause it. The EOOS user will then have the information to decide whether the problem is significant enough to warrant special contin­gency actions.

The software offers various benefits and values for the user. EOOS can help reduce Operation and Maintenance (O&M) costs by: (a) reducing the chance of a costly operational mistake. As unplanned events creep into a well-planned work schedule, you run the risk of unexpected reductions in plant safety. EOOS detects these safety problems that routinely escape the scrutiny of safety reviews based on train-level work windows, (b) by reducing the labor needed to perform safety reviews. An EOOS model integrates the safety impact of all work tasks affecting all risk significant safety functions into concise screen presentations and printed reports, (c) by providing credible, risk-based insights that minimize unnecessarily conservative requirements. EOOS results can become the basis for eliminating requirements that increase outage dura­tion, without a commensurate safety benefit.