Status - SSG-79
Revision von NS-G-3.1 (Ex DS258)
Beteiligte IAEO-Komitees: NUSSC, WASSC
Specific Safety Guide
This specific safety guide will supersede the IAEA safety guide NS-G-3.1, “External Human Induced Events in Site Evaluation for Nuclear Power Plants” and expand the scope from NPP to all nuclear installations. It will directly support Requirement 24 and the related paragraphs 5.33 to 5.37 of DS484 (future SSR-1).
The current safety guide NS-G-3.1 issued in 2002 needs an update addressing the following issues:
- Major changes in the requirement documents in higher hierarchy (NS-R-3 (Rev.1) and upcoming revision DS484);
- Considerations fulfilling the gap between the existing publication and the practices in IAEA Member States;
- Evolution of the techniques and advancement of technology in the assessment of external human-induced hazards.
The major changes mentioned above include the issues highlighted after the Fukushima Daiichi NPP accident. For instance, the new safety guide will need to consider provisions on the levels of hazards accounting for their uncertainties, provisions of managing events occurring in combination, provisions for a site with multiple facilities, and periodic reviews of site-specific hazards.
The revision will take into consideration feedback from technical safety review services, advisory services, and comments and practices shared during a technical meeting scheduled for April 2019 (aim of this technical meeting - discussing practices and methodologies of evaluating external human-induced hazards in site evaluation for nuclear installations).
The process to evaluate hazards consists of:
- identification of sources,
- identification of potential external events of the sources,
- screening of the potential external events,
- evaluation of hazards and
- characterization of loading conditions.
The proposed guide will cover the process of site evaluation up to this point. The Draft Safety Guide DS498 (revision of NS-G-1.5) will cover the process of design of nuclear installations against external hazards excluding earthquakes, which includes:
- design and evaluation of structures, systems and components and
- performance, assessment and acceptance criteria of the nuclear installation.
Evaluation of the effects of wilful human actions or malicious acts on nuclear installations are not included in the scope of this safety guide. The external human-induced events considered in the proposed guide will be of accidental origin. However, the methods to be described in it have some implications to evaluating impacts (for instance, pressure waves, heat, projectiles) of all external human-induced events.