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View documentNKS Programme Area: | NKS-R | Research Area: | Severe accidents | Report Number: | NKS-395 | Report Title: | Scenarios and Phenomena Affecting Risk of Containment Failure and Release Characteristics | Activity Acronym: | SPARC | Authors: | Pavel Kudinov, Sergey Galushin, Dmitry Grishchenko, Sergey Yakush, Yvonne Adolfsson, Lisa Ranlöf, Ola Bäckström, Anders Enerholm, | Abstract: | The report summarizes results achieved within the project NKS-SPARC. The project is motivated by apparently high sensitivity of effectiveness of severe accident management (SAM) strategy in Nordic type BWR to the uncertainties in physical phenomena (deterministic) and accident scenarios (stochastic). We employ ROAAM+ approach in order to address both epistemic and aleatory sources of uncertainty in a consistent manner. The state of the art review of Integrated Deterministic Probabilistic Safety Analyses (IDPSA) is presented. The ROAAM+ framework addressing all stages of the accident progression from initial plant damage states, through core degradation and vessel failure, melt ejection mode to ex-vessel melt-coolant interactions and debris coolability, is discussed in detail along with implementation details of ROAAM+ framework itself. Main findings of the analysis of effectiveness of SAM strategy in Nordic BWRs using ROAAM+ framework and main results are presented using failure domain maps. A conceptual approach for combined use of Probabilistic Safety Assessment (PSA) and Integrated Probabilistic Deterministic Safety Assessment (IDPSA) is illustrated. Methodological enhancements of PSA analysis, based on PSA and DSA integration are proposed. The project outcome will allow the end users to enhance understanding, completeness and consistency of safety analysis dealing with risk analysis in: management of severe accident issues; improved reliability analysis modelling methods for level 2 PSA; presentation of results in level 2 PSA, and related risk criteria; handling of modelling uncertainties. | Keywords: | ROAAM+, IDPSA, PSA, DSA, BWR, Severe accident, MELCOR, core degradation, steam explosion, debris coolability | Publication date: | 22 Aug 2017 | ISBN: | ISBN 978-87-7893-483-3 | Number of downloads: | 2818 | Download: | NKS-395.pdf |
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