PSR Process

Phase 1: Preparation of the PSR Project

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The first phase, Preparation of the PSR Project, must include an agreement with the regulatory body about the scope and timing of the review and the codes and standards that are going to be used.

All this information is recorded in the “PSR basis document” and it provides the scope, major milestones, including cut-off dates and methodology of the PSR, the safety factors to be reviewed, and the applicable national and international standards, codes, and practices. The process for categorizing, prioritizing, and resolving findings should also be agreed upon and set out in the basis document. The typical content of a PSR basis document is presented in the Appendix II of SSG-25.

The licensee and the regulatory body should define an appropriate point in time to ‘freeze’ the documents to be reviewed and the safety performance status of the plant to be considered as a basis for the PSR. This will ensure consistency across all parts of the PSR.

Phase 2: Conduct of the PSR

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In the second phase, Conduct of the PSR, the operating organization should carry out the review according to the “PSR basis document”. A review of safety factors should be carried out for all relevant operational states and accident conditions. An assessment for each safety factor should be made against current safety standards and operating practices as well as considering the interaction with other safety factors. Areas where either the licensing basis or current standards and practices are not achieved should be identified.

The review identifies positive and negative findings, and it should lead to enhancements for safety improvements and an integrated implementation plan. The typical lists of input and output information for each safety factor are provided in Appendix I of SSG-25.

The objective of the PSR global assessment is to determine the suitability of the NPP to continue operating based on a balanced view of the findings from the safety factor reviews. The global assessment should consider all the positive and negative findings of the PSR, as well as the proposed corrective actions and safety improvements and should evaluate the overall level of safety that will be achieved at the NPP after the PSR.

In case of negative findings, the global assessment should justify the improvements that cannot be reasonably and feasibly achieved. In addition, the risks associated with the unresolved negative findings must be assessed and proper justification for continued operation must be provided.

Overall conclusions and safety improvements considered to be reasonable and practicable in accordance with the global assessment should be documented in the final “PSR report”. Safety improvements should be listed in the “Integrated Implementation Plan” and then carried out on a schedule established with the regulatory body.

Phase 3: Regulatory Review

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In the third phase, named Regulatory Review, the regulatory body should review the PSR report prepared by the licensee as well as the proposed safety improvements. They should review the proposed Integrated Implementation Plan and define whether the licensing basis for the NPP is still valid.

According with SSG-25 , the regulatory body prepares an “Integrated Project report”, and it should specify the following:

• The regulatory body’s view of the adequacy of the PSR as documented in the reports submitted, including the safety improvements already implemented by the licensee.
• The regulatory body’s view of the adequacy of safety improvements identified by the licensee but not yet implemented.
• An evaluation of the time schedule for the integrated implementation plan proposed by the operating organization.

The end of the PSR report’s review involves several meetings but should lead to an agreement from both sides on an updated Integrated Implementation Plan for safety improvement.

Phase 4: Finalization of the Integrated Implementation Plan

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Finally, the fourth phase of a PSR process is called Finalization of the Integrated Implementation Plan. In this term, reasonable and practicable safety improvements included in the Integrated Implementation Plan should be carried out and finalized in accordance with the schedule agreed with the regulatory body.

The proposed plan should recognize the need to implement safety improvements as soon as reasonable and feasible, based on the global assessment of safety at the plant. Nevertheless, where an immediate and significant risk to the health and/or safety of workers or the public, or to the environment exists, the operator should promptly address it and should not wait for the completion of the PSR process.

It is important to notify the regulatory body when safety improvements are implemented and to inform them of any significant delays in completing the improvements beyond the agreed schedule. The review process is flexible and can be modified to comply with national regulations and incorporate the results of relevant studies and safety reviews.

According to SSG-25, the results of the review should be documented, and the documentation should include:

• The basis document for the PSR
• Reports on the review of each safety factor
• A report documenting the results of the global assessment
• The final PSR report, in which information on the proposed safety improvements and the integrated implementation plan are included, as well as a summary of the reports and safety factors and the global assessment.

The contents of these documents are described in Appendix II of SSG-25.

In general, the PSR outputs could be used in support of justification of LTO in the following ways:

• To obtain an overall assessment of actual plant safety
• To confirm that sufficient safety margins of SSCs exist for the next operational period
• To verify the effectiveness of the operating and maintenance programs for LTO
• To identify any safety concern(s) that require corrective actions
• To determine reasonable safety improvements to enhance plant safety and reliability
• To establish a corrective action plan

Record of Revisions

Number	Date	Description of Changes
0	6/11/2024	Initial version

Periodic Safety Review

Nuclear Power Plant

Long Term Operation