Document: NRC Regulatory Guide
Document ID: c7a40fcc-fc9d-4eb2-ad86-f9f5b0f04c82
Document Type: regulatory_guide
Title: Plant-Specific, Risk-Informed Decisionmaking:  Technical Specifications (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1920/ML19206A489.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.177
CFR Part: 
CFR Title: 

Content:
of total CDF and total LERF predicted for the plant and the change in CDF and LERF predicted for the proposed licensing basis changes. TS submittals for changes to CTs should also be evaluated against the risk-acceptance guidelines in this guide in addition to those in RG 1.174. Application of all the risk-acceptance guidelines to individual proposals for TS changes will be done in a manner consistent with Principle 4 in RG 1.174—changes to TS result in small increases in the risk to public health and safety. TS change evaluations may involve some small increase in risk, as quantified by PRA models. It is usually argued that such a small increase is offset by the many beneficial effects of the change that are not modeled by the PRA. The role of numerical guidelines is to ensure that the increase in risk is small and to provide a quantitative basis for the risk increase based on aspects of the TS change that are modeled or quantified. DG-1287, Page 21 In some instances, risk information submitted by a licensee may support a long-term CT extension (e.g. greater than 90 days). Limiting CT extensions to a backstop or a maximum CT limits extended exposure to single-failure susceptibility and compensates for the inherent uncertainty associated with PRAs. TS conditions addressed by CTs are entered infrequently and are inherently temporary by their very nature. As stated in Section 4.1.2 of Nuclear Energy Institute (NEI) 96-07, “Guidelines for Title 10 of the Code of Federal Regulations (10 CFR) Part 50.59 Evaluations” (Ref. 25), if a temporary change in support of maintenance activities is expected to be in effect during at-power operations for more than 90 days, then the provisions of 10 CFR 50.59, “Changes, Tests and Experiments,” would be applied to the temporary change in the same manner as a permanent change. Even though NEI 96-07 applies to conducting 10 CFR 50.59 evaluations, a parallel can be drawn to TS CT extensions, in that temporary configurations or