PSAM 16 - Paper Overview

PSAM 16 Conference Paper Overview

Welcome to the PSAM 16 Conference paper and speaker overview page.

Lead Author: Marina Roewekamp Co-author(s): John A. Nakoski, John.Nakoski@nrc.gov Attila Bareith, bareith@nubiki.hu Dana Havlín Nováková, dana.havlinnovakova@sujb.cz

Consideration of Combined Hazards Within PSA - A WGEV and WGRISK Perspective
After the Fukushima reactor accidents, combinations of hazards have gained more and more attention. As a result, the importance of adequate consideration of hazard combinations, particularly involving external hazards, in all types of safety assessments of nuclear installations has been recognized by the experts involved. Several national as well as international activities are ongoing with respect to combinations of hazards, including the extension of IAEA Safety Guides to better cover combined hazards, and one of the currently ongoing activities conducted jointly by the OECD Nuclear Energy Agency (NEA) Working Groups on Risk Assessment (WGRISK) and on External Events (WGEV) entitled “Combinations of External Hazards – Hazard and Impact Assessment and Probabilistic Safety Analysis (PSA) for Nuclear Installations”. This activity was initiated in 2020 addressing the state-of-the-art practices used in considering combinations of external hazards in the design and safety assessment of nuclear installations. The first phase of the activity covered a survey of members of both Working Groups in order to develop an informed understanding of the regulatory requirements and the technical approaches in WGEV and WGRISK member countries with regard to the treatment of combined external hazards and integrated hazard impacts. The survey included questions on regulatory requirements for hazard combinations analysis and their consideration in safety analyses, the use of a specific terminology and the frequencies for reviews and updates of the assessment. The survey questions also covered the specific approach for hazard combinations in the frame of siting and licensing for new nuclear power plants (NPPs) and possible differences compared to operating ones, the use of specific PSA guidance for hazard combinations and its application to support risk-informed decision-making (RIDM), and the review of protective measures against hazard combinations by the regulators. Individual member states provided examples of experiences with respect to hazard combinations. PSA needs were also considered in the survey including the underlying methodologies for identifying, interpreting, and screening combined external hazards as well as performing probabilistic hazard assessment suitable for use in PSA. Methodologies for plant response and fragility analysis, development of event sequence models including the role of plant personnel, and risk quantification along with the treatment of uncertainties were in the scope of the survey. PSA modelling of internal events and hazards consequential to external hazards or combinations of external hazards was also addressed in the survey. In the second phase of the activity, a joint workshop of WGEV and WGRISK will take place to involve a broader range of engineers, scientists, risk analysts and other experts in this field to address key issues and identify technology gaps. Insights from the survey on which hazards realistically should be combined will be discussed, with a specific focus on risk assessment for accidents induced by combinations of hazards at full power as well as in low power and shutdown states. The discussions are expected to help better identify and characterize important hazard combinations and understand the state-of-the-art in assessing the integrated impact of combined hazards and in developing PSA for combined external hazards. This paper presents the status of this international activity and some intermediate results with respect to PSA for combined external hazards.

Consideration of Combined Hazards Within PSA - A WGEV and WGRISK Perspective

After the Fukushima reactor accidents, combinations of hazards have gained more and more attention. As a result, the importance of adequate consideration of hazard combinations, particularly involving external hazards, in all types of safety assessments of nuclear installations has been recognized by the experts involved. Several national as well as international activities are ongoing with respect to combinations of hazards, including the extension of IAEA Safety Guides to better cover combined hazards, and one of the currently ongoing activities conducted jointly by the OECD Nuclear Energy Agency (NEA) Working Groups on Risk Assessment (WGRISK) and on External Events (WGEV) entitled “Combinations of External Hazards – Hazard and Impact Assessment and Probabilistic Safety Analysis (PSA) for Nuclear Installations”. This activity was initiated in 2020 addressing the state-of-the-art practices used in considering combinations of external hazards in the design and safety assessment of nuclear installations. The first phase of the activity covered a survey of members of both Working Groups in order to develop an informed understanding of the regulatory requirements and the technical approaches in WGEV and WGRISK member countries with regard to the treatment of combined external hazards and integrated hazard impacts. The survey included questions on regulatory requirements for hazard combinations analysis and their consideration in safety analyses, the use of a specific terminology and the frequencies for reviews and updates of the assessment. The survey questions also covered the specific approach for hazard combinations in the frame of siting and licensing for new nuclear power plants (NPPs) and possible differences compared to operating ones, the use of specific PSA guidance for hazard combinations and its application to support risk-informed decision-making (RIDM), and the review of protective measures against hazard combinations by the regulators. Individual member states provided examples of experiences with respect to hazard combinations. PSA needs were also considered in the survey including the underlying methodologies for identifying, interpreting, and screening combined external hazards as well as performing probabilistic hazard assessment suitable for use in PSA. Methodologies for plant response and fragility analysis, development of event sequence models including the role of plant personnel, and risk quantification along with the treatment of uncertainties were in the scope of the survey. PSA modelling of internal events and hazards consequential to external hazards or combinations of external hazards was also addressed in the survey. In the second phase of the activity, a joint workshop of WGEV and WGRISK will take place to involve a broader range of engineers, scientists, risk analysts and other experts in this field to address key issues and identify technology gaps. Insights from the survey on which hazards realistically should be combined will be discussed, with a specific focus on risk assessment for accidents induced by combinations of hazards at full power as well as in low power and shutdown states. The discussions are expected to help better identify and characterize important hazard combinations and understand the state-of-the-art in assessing the integrated impact of combined hazards and in developing PSA for combined external hazards. This paper presents the status of this international activity and some intermediate results with respect to PSA for combined external hazards.

Paper MA222 Preview

Author and Presentation Info

Lead Author Name: Marina Roewekamp (Marina.Roewekamp@grs.de)

Bio: - Diploma in Physics PhD (Dr. rer. nat. In Physical Chemistry / Materials Science) from University of Bonn - Senior Chief Expert for Hazards and PSA at GRS – the Federal German Nuclear Technical Safety Organization – for > 33 years - PSA work: mainly performing and/or reviewing Level 1 PSA, particularly for Internal and External Hazards (incl. hazard combinations) - Member of the German PSA Expert Panel for > 15 years - Former Chair and actual Vice Chair of OECD/NEA/CSNI Working Group on Risk Assessment (WGRISK) - Chair of OECD/NEA CSNI Expert Group on Fire Risk (EGFR) and of Management Board of OECD/NEA FIRE (Fire Events Records Exchange) Project - Consultant and/or reviewer for various IAEA Guides (SSG-64, SSG-67, SSG-68, DS523 (revision of SSG-3 on Level 1 PSA), DS528 (revision of SSG-4 on Level 2 PSA), TECDOCS on MUPSA, Advanced PSA Methods, Safety Assessment of Nuclear Installations Against Combinations of External Hazards, etc. - IAPSAM Board of Directors member since

Country: Germany
Company: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH
Job Title: Chief Senior Expert

PSAM 16 Conference Paper Overview

Welcome to the PSAM 16 Conference paper and speaker overview page.

Paper MA222 Preview

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