Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report

Stefan Authén, Kim Björkman, Jan-Erik Holmberg, Josefin Larsson

    Research output: Book/ReportReport

    Abstract

    Digital protection and control systems are appearing as upgrades in older nuclear power plants (NPPs) and are commonplace in new NPPs. To assess the risk of NPP operation and to determine the risk impact of digital system upgrades on NPPs, quantitative reliability models are needed for digital systems. Due to the many unique attributes of these systems, challenges exist in systems analysis, modeling and in data collection. Currently there is no consensus on reliability analysis approaches. Traditional methods have clearly limitations, but more dynamic approaches are still in trial stage and can be difficult to apply in full scale probabilistic safety assessments (PSA). The number of PSA:s worldwide including reliability models of digital I&C systems are few. A comparison of Nordic experiences and a literature review on main international references have been performed in this pre-study project. The study shows a wide range of approaches, and also indicates that no state-of-the-art currently exists. The study shows areas where the different PSA:s agree and gives the basis for development of a common taxonomy for reliability analysis of digital systems. It is still an open matter whether software reliability needs to be explicitly modelled in the PSA. The most important issue concerning software reliability is proper descriptions of the impact that software-based systems has on the dependence between the safety functions and the structure of accident sequences. In general the conventional fault tree approach seems to be sufficient for modelling reactor protection system kind of functions.
    Original languageEnglish
    Place of PublicationRoskilde
    Number of pages29
    Publication statusPublished - 2010
    MoE publication typeD4 Published development or research report or study

    Publication series

    SeriesNKS Reports
    Volume230

    Fingerprint

    Reliability analysis
    Nuclear power plants
    Software reliability
    Taxonomies
    Accidents
    Systems analysis
    Control systems

    Keywords

    • Digital I&C system
    • probabilistic safety assessment
    • reliability
    • nuclear power plant safety

    Cite this

    Authén, S., Björkman, K., Holmberg, J-E., & Larsson, J. (2010). Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report. Roskilde. NKS Reports, Vol.. 230
    Authén, Stefan ; Björkman, Kim ; Holmberg, Jan-Erik ; Larsson, Josefin. / Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report. Roskilde, 2010. 29 p. (NKS Reports, Vol. 230).
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    Authén, S, Björkman, K, Holmberg, J-E & Larsson, J 2010, Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report. NKS Reports, vol. 230, Roskilde.

    Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report. / Authén, Stefan; Björkman, Kim; Holmberg, Jan-Erik; Larsson, Josefin.

    Roskilde, 2010. 29 p. (NKS Reports, Vol. 230).

    Research output: Book/ReportReport

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    AU - Björkman, Kim

    AU - Holmberg, Jan-Erik

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    Authén S, Björkman K, Holmberg J-E, Larsson J. Guidelines for reliability analysis of digital systems in PSA context — Phase 1 Status Report. Roskilde, 2010. 29 p. (NKS Reports, Vol. 230).