Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

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assumptions and uncertainties from each contributor that might affect the decision process. Combining risk impacts from the individual contributors is prudent when the contributors are closely related in terms of analysis assumptions and uncertainty. Contributors could also be related if they impact on the same plant functions, for example. SRP 19-26 Conversely, for contributors that are not closely related, risk impacts from each change should be evaluated on an individual basis. Finally, combined changes should not trade many small risk decreases for a large risk increase (i.e., create a new significant contributor to risk). It is expected that implementation of combined change requests will improve, or at least maintain, the overall plant risk profile. A desirable risk profile is one in which no contributors are overly dominant. Therefore, proposed changes should not create or exacerbate a risk imbalance either in terms of dominant plant elements (SSCs or operator actions) or accident sequences. III.3 ELEMENT 3: DEVELOP IMPLEMENTATION AND MONITORING 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 Regulatory Guide 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 that 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