Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
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Content:
exacerbate a risk imbalance either in terms of dominant plant elements (SSCs or operator actions) or accident sequences. SRP 19-26 Develop Implementation and Monitorincq Strategies Implementation and monitoring strategies are important in most risk-informed processes since they can provide an early indication of unanticipated degradation of SSCs or other plant performance factors under the proposed changes. In addition, these strategies may be needed to ensure that the plant will effectively maintain the performance of SSCs that are relied upon to justify the proposed change to the LB. Section 2.3 of RG 1.174 provides guidance for the suggested process related to this issue. The primary goal of the monitoring program should be to ensure that no adverse degradation occurs because of the changes to the LB. These programs should therefore address the possibility that the aggregate impact of changes which affect a large class of SSCs could lead to an unacceptable increase in the number of failures attributable to unanticipated degradation, including possible increases in common cause failure mechanisms. Reviewers should evaluate the implementation and monitoring strategies on the basis of findings obtained from the traditional engineering and probabilistic evaluations. When broad implementation is proposed over a short period of time, reviewers should verify that this is consistent with the traditional engineering evaluations, defense-in-depth considerations (including common cause failure), and risk evaluation models and assumptions. When there is a need to gain additional performance insights given a change in requirements, reviewers should verify that the licensee has proposed a phased approach to implementation. If this phased approach involves plan implementation for different SSC groups at different times, reviewers should also assess the basis for the licensee's grouping criteria, keeping in mind the potential common cause failures. Monitoring should be applied