SwRI: Probabilistic Safety Assessment Services, Center for Nuclear Waste Regulatory Analyses

Safety and risk/reliability-related decisions are often made under uncertainties resulting from limited data. To risk-inform decisions under such uncertainties, Southwest Research Institute (SwRI) conducts comprehensive studies using probabilistic safety assessment methodologies to assess safety of engineered structures and facilities.

Using fault tree and event tree methods and the probabilistic framework of the PCSA Tool, engineers and risk analysts estimate reliability of components, analyze sequences of events, and assess the risk from spent fuel handling facilities.

As a leader in developing and applying probabilistic methods, SwRI geoscientists, engineers, and risk analysts focus on innovations for understanding and quantifying natural hazards (e.g., earthquake, landslides, floods) and manmade hazards (e.g., aircraft crash), and their consequence on infrastructures and facility operations.

Using natural and manmade hazards as initiating events, and equipped with the knowledge of design codes, standards, and regulations, while using a suite of well-known techniques such as What-If and Failure Models and Effects Analyses (FMEA), SwRI risk analysts conduct operational hazard analyses. SwRI engineers evaluate hazard scenarios caused by equipment and system failures, human errors, and external events.

The PCSA Tool, developed by SwRI, enables SwRI engineers to conduct systematic and comprehensive safety analyses, specifically:

• Hazard analysis

• System reliability and uncertainty analyses

• Event sequence analysis

• Consequence analysis

• Estimation of risk to workers and the public

• Determination of risk significance of structures, systems, and components

Engineers conduct event sequence analysis using fault tree and event tree techniques to

• Estimate likelihood of events using historical and new data

• Conduct dependent failure analysis

• Account for common cause failure

• Quantify human error probability

• Explore the effect of data uncertainty on modeling results

• Identify through sensitivity studies the most important factors or structures, systems, and components relied upon for safety

SwRI can also assist clients in simplifying complex probabilistic safety assessments for use in public outreach.

For more information about the probabilistic safety assessment capabilities at SwRI or how you can contract with SwRI, please contact Dr. Sitakanta Mohanty at smohanty@swri.org or (210) 522-5185.