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: 

Content:
on and human actions, • whether the screening analysis is affected. When HFEs represent responses to failures of the SSCs impacted by the change, reviewers may want to focus their resources on these HFEs in the following ways: • Identify any human actions that compensate for events affected by the proposed application, and ensure that the licensee did not claim inappropriate credit for these events. For human actions that are used to compensate for a basic event probability increasing as a result of proposed changes, licensee actions to ensure operator performance at the level credited in the risk analysis should also be a part of the change request. • Ensure that appropriate justification is provided when the licensee takes credit for post-accident recovery of failed components (repair or other non-proceduralized manual actions, such as manually forcing stuck valves to open). Reviewers should also ascertain whether the identified recovery action is obvious, feasible (given the time and physical constraints), and supportable by plant programs such as training. • Ensure that the licensee assessed whether the conditions under which the human actions are to be performed have changed significantly so that the HEP should be modified. Reviewers should also be aware that the impact of the change can be obscured if the accident sequences that do not contain affected SSCs are artificially increased in value by HEPs that are too large. These cases will impact applications involving risk categorization by lowering the relative contribution of the affected SSCs. An understanding of these effects can be obtained from sensitivity analyses performed by removing the pertinent HEPs or by using more realistic values for the HEPs. Another consideration associated with the potential masking of important SSCs is that the SSCs might not be included in the model used to perform the evaluation of risk. This can happen in several ways: • Cutsets or scenarios containing the SSCs