Risk & Safety Working Group (RSWG)

Generation IV nuclear energy systems will aim to achieve the following safety goals:

  • to excel in safety and reliability;
  • to have a low likelihood and degree of reactor core damage;
  • to eliminate the need for offsite emergency response. 

A Risk-informed Framework for Safety Design of Generation IV Systems (June 2023)

This paper is intended to provide an example of risk-informed approach as an iterative process, complementary to the traditional deterministic approach, for a comprehensive search of event sequences including their expected frequency and consequences to understand the risk. The approach can also support safety classification of plant equipment and defence-in-depth (DiD) assessment.

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Safety Design Criteria (SDC) for Generation IV Very High Temperature Reactor (VHTR) System (June 2023)

This report focuses on SDC for VHTR system with the objective of establishing reference requirements for the safety design of VHTR structures, systems, and components consistent with the GIF safety goals and basis for safety approach. The report is developed in collaboration with the VHTR System Steering Committee.

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Safety Design Criteria (SDC) for Generation IV Gas-Cooled Fast Reactor System (September 2022)

This report was prepared by the GFR Conceptual Design and Safety Project of the Generation IV International Forum (GIF).
The objective of the GFR SDC is to present reference criteria for the safety design of structures, systems and components of an GFR system with the aim of achieving the safety goals of a Generation-IV reactor system. The reference criteria are systematically and comprehensively explained in the SDC.

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Gas-Cooled Fast Reactor System Safety Assessment (September 2022)

A necessary step in the development of a commercial GFR is the establishment of an experimental demonstration reactor for qualification of the refractory fuel elements and for a full-scale demonstration of the GFR-specific safety systems. The proposed demonstration reactor for the reference GIF GFR concept will be ALLEGRO: A low power reactor (50 - 150 MWth) with the ability to operate in different core configurations starting from a “conventional” core featuring steel-cladded MOX fuelled pins and followed with all-ceramic fuel elements in the latter stages of operation.

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Basis for the Safety Approach for Design & Assessment of Generation IV Nuclear Systems (revision, 2 July 2021)

This report is an update for the first version of GIF Basic Safety Approach that was published in 2008 as the first major product of the Risk and Safety Working Group (RSWG). It reflects the experience gained from development and application of the Integrated Safety Assessment Methodology (ISAM) to Gen-IV design tracks and the lessons from the Fukushima Dai-ichi accident as articulated in the new requirements issued by various international organizations such as the IAEA and OECD. The report also provides a high-level summary of the safety related achievements of the past ten years to supplement the objectives, principles, and attributes discussed in the original report to continue guiding the ongoing R&D activities.

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Lead-cooled Fast Reactor (LFR) System Safety Assessment (2020)

This document was prepared as a safety assessment for the Generation IV LFR system. The objective of the report is to review and identify the main safety advantages and possible challenges of the technology, to assess the current status of safety-related research & development (R&D) activities, and to identify future R&D needs for the LFR system. In preparing this analysis, the LFR pSSC has placed emphasis on the assessment of the fulfillment of the Generation IV goals, to highlight the attractiveness of the LFR technology for future extensive implementation. The report concludes that gaining safety and operational experience feedback through licensing and operation of demonstration plants is a prerequisite to bring the LFR to the industrial deployment. 

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Very High Temperature Reactor (VHTR) System Safety Assessment (2018)

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Supercritical-water-cooled reactor system (SCWR) System Safety Assessment (2018)

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Sodium-Cooled Fast Reactor (SFR) System Safety Assessment (2017)

This document was prepared as a safety assessment document for the Generation IV SFR systems, through the feedbacks between RSWG and SFR System Steering Committee. The main aim of this document is to identify strengths of the Generation IV SFR system based on proven technology and equipment as well as areas that need further development to satisfy the GIF safety and reliability goals. Contents of this document include “performance goal”, “feedback from operation experiences”, “ongoing safety-related R&D”, “management of design extension conditions”, and “summary of progress needed”.

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Super-Critical Water-cooled Reactors (SCWR) Risk and Safety Assessment White Paper (2017)

This white paper provides an overview of activities in the application of the Integrated Safety Assessment Methodology (ISAM) to the GIF Super-Critical Water-cooled Reactor (SCWR) design tracks. It also documents the identified future R&D needs for the conceptual design of SCWR systems to improve risk and safety performance of SCWRs.

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Gas-cooled Fast Reactor (GFR) Risk and Safety Assessment White Paper (2016)

This paper presents the application of the Integrated Safety Assessment Methodology (ISAM), developed by the Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG), to the Gas-Cooled Fast Reactor (GFR). Developed in the framework of the Euratom project SARGEN_IV, under the supervision of the GFR System Steering Committee (SSC) and RSWG, the paper compiles information that has been generated within the project and has been collected in the GFR-related Euratom projects GCFR STREP and GoFastR. After presenting a short overview of ISAM, the design of GFR and its demonstrator ALLEGRO are reported in more detail and then the results of the ISAM application are summarized.

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Sodium-cooled Fast Reactor (SFR) Risk and Safety Assessment White Paper (2016)

This paper, prepared jointly by Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG) and the SFR Systems Steering Committees (SSCs), presents the status of the Integrated Safety Assessment Methodology (ISAM) for Sodium-cooled Fast Reactor (SFR) for further research and development. The intent is to demonstrate the adequacy of safety related design; to identify R&D needs to qualify safety related provisions, and to recommend directions for optimizing its risk and safety performance. The three main objectives of this work, identified during the first workshop which brought together SSC representatives and RSWG members, are: capturing in the short-term salient features of the design concepts that impact their safety performance; identifying crosscutting studies that assess safety design or operating features common to various GIF systems; and suggesting beneficial characteristics of the design of future nuclear power plants that should be addressed in subsequent GIF activities.

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Very High Temperature Reactor (VHTR) Risk and Safety Assessment White Paper (2015)

The purpose of this paper is to investigate the feasibility of applying the Integrated Safety Assessment Methodology (ISAM) to the VHTR system. Developed by the Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG), ISAM consists of a set of tools to aid in safety design of advanced reactor concepts. This paper summarizes the ISAM tools, provides an overview of VHTR technology, and the preliminary assessment of ISAM tools in application to VHTR safety design.

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Lead-cooled Fast Reactor (LFR) Risk and Safety Assessment White Paper Revision 8 (2014)

This document presents the application of the Integrated Safety Assessment Methodology (ISAM), developed by the Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG), to the Lead-Cooled Fast Reactor (LFR). The document includes a summary of the existing common features of the three LFR reference systems (ELFR, BREST, SSTAR), and then presents an application of ISAM to the ALFRED demonstrator since, for this system, a consistent set of information has been disclosed and is available for the application. After presenting a short overview of ISAM and a short summary of the three reference LFR systems, the ALFRED design is reported in more detail and then the results of the ISAM application are summarized.

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ISAM (2011) and ISAM GDI (2014)
A principal focus of the Generation IV (Gen IV) International Forum’s Risk and Safety Working Group charter is the development and demonstration of an integrated methodology that can be used to evaluate and document the safety of Gen IV nuclear systems. The first RSWG report issued in 2008 presented the “Basis for the Safety Approach for Design & Assessment of Generation IV Nuclear Systems.”  Following its mandate, in 2011, the RSWG prepared a document that describes the methodology, called the Integrated Safety Assessment Methodology (ISAM), for use throughout the Gen IV technology development cycle.  To help facilitate the use of the methodology, in 2014, the RSWG developed a supporting Guidance Document for ISAM (GDI) to provide the users with further help for the ISAM implementation.

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Basis for the Safety Approach for Design and Assessment of Generation IV Nuclear Systems 
Revision 1 (2008)
This document, the first major work product of the Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG), presents the findings and recommendations of the group based on its work to date. Much additional work remains to be done by the RSWG. However, the objectives, principles, attributes, and tools presented in this document are intended to immediately provide designers of Generation IV systems with concepts and methods that can help guide their R & D activities in a way that promotes the safety basis and efficient licensing of advanced nuclear technologies.

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