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:
eptance guidelines (Sections 2.2.4 and 2.2.5 of Regulatory Guide 1.174) describe acceptable levels of risk increase as a function of total core damage frequency (CDF) and large early release frequency (LERF) and the manner in which the acceptance guidelines should be applied in the review and decisionmaking process. Reviewers should note that the guidelines serve as a point of reference for gauging risk impact but are not legally binding requirements. For non-risk-informed license amendment requests, the preliminary assessment would be qualitative, with a decision based on engineering judgment, since quantitative risk information would not generally be presented in submittals that are not risk informed. If “special circumstances” are believed to exist, the reviewers will explore in more detail the underlying engineering issues contributing to the risk concern, as well as the potential risk significance of the license amendment request. The staff should inform and engage the licensee as early as possible in the evaluation process when it believes that a special circumstance may exist and is considering the need for risk information. “Special circumstances” represent conditions or situations that would raise questions about whether there is adequate protection and that could rebut the normal presumption of adequate protection from compliance with existing requirements. In such situations, undue risk may exist even when all regulatory requirements are satisfied. In general, a special circumstance may exist if (1) the situation was not identified or specifically addressed in the development of the current set of regulations and could be important enough to warrant a new regulation (e.g., a risk-informed regulation) if such situations were encountered on a widespread basis and (2) the reviewer has knowledge that the risk impact is not reflected by the licensing basis analysis and has reason to believe that the risk increase would warrant denial or attaching