Microcomputer-based probabilistic risk assessment for nuclear power plant safety studies

Probabilistic risk assessment (PRA) information in the analysis of safety issues pertaining to nuclear power plant systems has been underutilized in the past due to the large effort required to input the PRA data and to the large size of the computers needed to run PRA codes. The microcomputer-based Integrated Reliability and Risk Analysis System (IRRAS) and the System Analysis and Risk Assessment System (SARA), recently developed at the Idaho National Engineering Laboratory, have greatly enhanced the ability of nuclear power plant analysts to use PRA techniques in their decision-making and analysis of safety issues. IRRAS is a tool for modeling and analyzing systems reliability and risk that allows the analyst to create, modify, update, and reanalyze a plant PRA to keep the risk assessment current with the plant's configuration and operation. The PRA is created and edited using a graphical fault tree editor, which significantly enhances the speed and accuracy with which the PRA data can be manipulated. The SARA system, incorporating the PRA data input in IRRAS, is used to analyze safety issues in nuclear power plants. To simulate changes to plant systems, SARA users alter the failure rates of basic events of the plant system models. Theymore » then evaluate the significance of these changes through the calculation of the resultant core damage and accident sequence probabilities and importance measures. IRRAS and SARA demonstrate that reliability and risk analysis studies of nuclear power plants, as well as of any other complex systems such as chemical plants or the space shuttle, can be performed very effectively on microcomputers, providing powerful and flexible tools for the safety analyst.« less