International survey of living PSA and safety indicators

Jan Holmberg, Kari Laakso, Esko Lehtinen, Gunnar Johanson, Staffan Björk

    Research output: Book/ReportReport


    This report contains an international overview of applications of living probabilistic assessment and development of operational safety indicators. Features of an ideal living PSA tool are summarized as well as a limited survey of code systems for managing a living probabilistic safety assessment (living PSA) is included. The international survey is used as an input for planning and performance of related tasks within the Nordic NKS/SIK-1 project conducted in 1990-93. The research notes are distributed to the Nordic organizations involved or interested in the subject. The report includes an overview and conclusions from technical reports and articles available and presentations and discussions related to development and use of the above methods for the evaluation and management of the operational safety of nuclear power plants. A large part of this material is based on material collected and discussed in connection to international specialist meetings relating to the subjects. In the area of living PSA tools there are many computer codes being developed. The present versions approach rapidly the level of usability needed for performing and maintaining living PSA and continuous risk monitoring. The living PSA applications are still in most cases research efforts in which the applicability of the PSA technique is tested in a small scale. For the moment, there are very few actual living PSA applications actively in use at the plants. The performance and safety indicators have been in a strong development phase during the last few years. Many utilities, regulatory bodies and international organizations have started to use performance indicators for quantitative evaluation of nuclear power plant operations. It is generally emphasized that performance and safety indicators are intended to be one of the several tools for use by plant and regulatory staff when tracking contributing factors of deteriorating as well as improving developments. Subsequently, the use of numerical indicators is expected to facilitate a more efficient utilization of operating experiences for making decisions on corrective actions to be taken at the plant. The use of the probabilistic methods for operational safety monitoring is encouraged, although a probabilistic approach also has met with some opposition. In any case, it is recommended that international cooperative research continues with the development of applying safety indicator concepts and operating experience feedback practices to dynamic and living PSA modelling.
    Original languageEnglish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages197
    ISBN (Print)951-38-4059-X
    Publication statusPublished - 1992
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Meddelanden - Research Notes


    • nuclear power plants
    • safety
    • risk analysis
    • software


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