Software tools for PRA

Probabilistic Risk Assessment (PRA) is performed to assess the probability of failure or success of a system's operation. Results provided by the risk assessment methodology are used to make decisions concerning choice of improvements to the design. PRA has been applied or recommended to NASA space applications to identify and mitigate their risks. The complexity of these tasks and varied information sources required for space applications makes solving them manually infeasible. Software tools are mandated. To date, numerous software tools have been developed and claimed as PRA solutions. It is always a concern which software best fits a particular PRA. The authors conducted a limited scope PRA on a NASA application using four different Reliability/PRA software tools (Relex, QRAS, SAPHIRE, GoldSim), which were readily available. The strength and weakness for each tool are identified and discussed. Recommendations on how to improve each tool to better satisfy NASA PRA needs are discussed.