Experience from Level 2 Site Risk Analysis for Nordic Power Plants

Jan-Erik Holmberg, Stefan Authén, Ola Bäckström, He Xuhong, Salvatore Massaiu, Tero Tyrväinen

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review


    The objective with the SITRON (SITe Risk On Nuclear installations) project has been to search for practical approaches for Nordic utilities to assess the site level risk. This paper presents the findings from the performance of level 2 PSA, i.e., the assessment of radioactive release risk from multiple units. Qualitatively, a multi-unit level 1 and 2 PSA are similar in terms of identifying dependencies. Level 2 PSA may bring some additional dependencies that are not relevant for level 1 PSA. Quantitatively, the difference in the used risk metrics can have some practical implications. In level 1 PSA, risk metrics are the frequencies of combinations of core damages (one, two, ..., all units). In level 2 PSA, risk metric is the frequency of a certain release category (small, large, early, late), which is determined by the aggregated release rather than number of releases. The need to quantify various accident sequences is thus much dependent on the applied safety goal for level 2 PSA. Further, pilot studies indicate that inter-unit dependencies in level 2 safety functions have less influence on results than inter-unit dependencies in level 1 safety functions.
    Original languageEnglish
    Title of host publicationProceedings of the 29th European Safety and Reliability Conference, ESREL 2019
    EditorsMichael Beer, Enrico Zio
    Place of PublicationSingapore
    PublisherEuropean Safety and Reliability Association (ESRA)
    ISBN (Electronic)978-981-11-2724-3
    Publication statusPublished - Sept 2019
    MoE publication typeA4 Article in a conference publication
    Event29th European Safety and Reliability Conference, ESREL 2019 - Welfenschloss, Hannover, Germany
    Duration: 22 Sept 201926 Sept 2019


    Conference29th European Safety and Reliability Conference, ESREL 2019
    Internet address


    • site risk analysis
    • nuclear power plant
    • level 2 PSA
    • probabilistic safety assessment
    • probabilistic risk analysis
    • multi-unit
    • severe accident
    • risk metrics
    • human reliability analysis


    Dive into the research topics of 'Experience from Level 2 Site Risk Analysis for Nordic Power Plants'. Together they form a unique fingerprint.

    Cite this