[en] This report, which compiles information on a comprehensive set of PSA applications in the areas of NPP design, operation, and accident mitigation and management, is the culmination of an IAEA project on PSA Applications and Tools to Improve NPP Safety. In this regard, the Technical Committee Meeting (TCM) held in Madrid in February 1998 allowed participants to review and provide very valuable comments for this report. Several important facts related to PSA and its applications were highlighted during this TCM: living PSAs are the basis for the risk informed approach to decision making; development and use of safety/risk monitors as tools for configuration management is spreading fast; the different uses of PSA to support NPP testing and maintenance planning and optimization are amongst the most widespread PSA applications; plant specific PSAs are being used to support the safety upgrading programmes of plants built to earlier standards; not all countries have a regulatory framework for the use of the probabilistic approach in decision making. Some countries are still far from 'risk-informed' regulation, and this means that there is still considerable work ahead, both for regulators and utilities, to clarify approaches, to establish a framework and to reach a common understanding in relation to the use of PSA in decision making. This report is based on the premise that the use of PSA can provide useful information for the decision maker. This report is intended to provide an overview of current PSA applications. Section 2 addresses the PSA application process, outlines the general requirements for PSA tools and provides a discussion on PSA aspects such as PSA level, scope and level of detail, which have to be considered when planning/performing PSA applications. Section 3 discusses the technical aspects of individual applications and is divided into three parts. Section 3.1 is dedicated to the design related PSA applications. The second part of Section 3 considers the PSA applications that are related to the plant operations and the daily safety related activity of the plant personnel. Section 3.3 deals with PSA applications used to support the mitigation and management of incidents and accidental situations. Section 3 is not intended to be complete in its coverage of uses of PSA, but has focused on those applications that have been reported extensively in the literature. It is however, expected that future uses will probably be variants of the examples discussed in this part of the report. Section 4 discusses the regulatory perspective on the use of PSA, and points out the main issues and regulatory concerns in the area of the PSA applications. Section 5 discusses the establishment of numerical criteria for use in decision making using PSAs. Such criteria are likely to be different from country to country as they must relate to the regulatory framework adopted in each country. Therefore, the discussion concentrates on general issues, but gives specific examples to illustrate application of those principles