DS535 - Periodic Safety Review for Nuclear Power Plants

Status: STEP 5

Revision von SSG-25

Beteiligte IAEO-Komitees: NUSSC, RASSC, WASSC, EPReSC, NSGC

Specific Safety Guide

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Background Information

Operational nuclear power plants are generally subject to routine reviews of plant operational safety, or special safety reviews following operational events, to drive continuous safety improvements throughout their operational lifetime.

However, these routine safety reviews are focused reviews and typically do not inclusively consider changes in safety standards and technological developments, the cumulative effects of plant ageing, plant modifications, feedback of operating experience, organizational and management issues, site related aspects or developments in science and technology.

To capture the aggregate effect of these topics on plant safety, Requirement 12 of IAEA Safety Standards Series No. SSR-2/2 (Rev. 1), Safety of Nuclear Power Plants: Commissioning and Operation calls for the periodic conduct of a comprehensive, integrated safety review, commonly referred to as a ‘periodic safety review’ (PSR), which relies on a systematic and comprehensive process whereby up-to-date standards and technological developments are considered to provide assurance of the continued viability of the plant’s licensing basis, given the cumulative aspects of emerging national and international standards, evolving regulatory requirements, plant ageing, operating experience, and technological development. PSR thus provides an effective way to obtain an overall view of actual plant safety and the quality of the safety documentation, and to determine reasonably practicable modifications for compliance with applicable standards with the aim of enhancing the safety of the plant by further reducing the likelihood and the potential consequences of accidents. Specifically, the assessment for the next operational period documents the following:

• The extent to which the plant conforms to current standards and practices;
• The extent to which the (updated) licensing basis will remain valid to next operational period, or to the end of the plant’s proposed extended operating life;
• The adequacy of the arrangements that are in place to maintain plant safety for the next operational period;
• The reasonably practicable safety improvements to be implemented to resolve the safety issues that have been identified.

It is recognized that (in some jurisdictions) the PSR is consistently used to support decision making on periodic permission for continued operation. However, the PSR can provide evaluation of safety factors related to operation beyond the original planned or licensed lifetime, usually referred to as ‘long term operation’ (LTO). These safety factors include (among others) plant design safety, actual condition of structures, systems and components (SSCs) important to safety, ageing and equipment qualification.

The purpose of this Safety Guide is to provide recommendations and guidance on the conduct of a PSR for an existing nuclear power plant to determine whether they conform with current requirements and respective recommendations provided in existing IAEA safety standards.

This publication will apply to operating nuclear power plants. It will revise the specific topics addressed in SSG-25 to reflect changes made to IAEA safety standards since the publication of SSG-25 in 2013. The anticipated revisions concern namely Section 3 (Input from the periodic safety review in assessing long term operation or licence renewal), Section 5 (Safety factors in a PSR) and Section 6 (Global assessment).