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:
s could mean that the equipment associated with those actions might be overlooked in the change process. c. Evaluation Findings The staff safety evaluation report should include language equivalent in effect to the following: • The modeling of human performance is appropriate. • Post-accident recovery of failed components is modeled in a defensible way. Recovery probabilities are realistically quantified. The formulation of the model shows decisionmakers the degree to which the apparently low risk significance of certain items is dependent on credit for recovery of failed components (restoration of component function, as opposed to actuation of a compensating system). • When human actions are proposed as compensatory measures as part of a proposed change, licensee actions to ensure operator performance at the level credited in the risk analysis (e.g., by training, procedures, etc.) are also a part of the change request. A.9 Sequence Quantification a. Areas of Review The staff would not generally anticipate the need to perform a detailed review of the quantification of the change in risk; however, some details of the quantification process should be confirmed. Specifically, reviewers should be confident that the licensee's evaluation process is sufficient to account for the potential effects of the proposed change on modeling simplifications and SRP 19-A19 assumptions made during the quantification of risk. In addition, the staff should ensure that the chosen sequence truncation limits are appropriate so that important sequences are not discarded and final results are not sensitive to the chosen truncation limit. b. Review Guidance and Procedures Reviewers should verify that model simplifications and assumptions made during the quantification process are properly accounted for in evaluating of the change in risk, as illustrated by the following examples: • Reviewers should ensure that the licensee accounted for model asymmetries during the application of the