Reflecting on older analysis practices, passive components failures seldom receive explicit treatment in PSA. to expand the usefulness of PSA and to raise the realism in plant and system models the Swedish Nuclear power Inspectorate has undertaken a multi-year research project to establish a comprehensive passive components database, validate failure rate parameter estimates and model framework for enhancement of integration passive components failures in existing PSAs. Phase 1 of the project (completed in Spring 1995) produced a relational data base on worldwide piping system failure events in nuclear and chemical industries. Approximately 2300 failure events allowed for data exploration in Phase 2 to develop a sound basis for PSA treatment of piping system failure. In addition, a comprehensive review of the current consideration of LOCA in PSA and a comprehensive review of all available literature in this area was undertaken.