Document: NUREG-0800
Document ID: 7f6b0af0-d79e-4704-9eac-aa03109a7731
Document Type: srp
Title: RISK-INFORMED DECISIONMAKING: TECHNICAL SPECIFICATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0425/ML042520260.pdf
Revision Date: 2023-06
Chapter: 16
Section ID: 16.1
CFR Part: 
CFR Title: 

Content:
nt to which the licensee has demonstrated that its PRA is valid for assessing the proposed TS changes and the overall impact of the TS change on plant risk. Rev. 0 - August 1998 SRP 16.1-14 b. Tier 2: Avoidance of Risk Significant Plant Configurations for TS AOT Changes The licensee's assessment should also provide reasonable assurance that risk-significant plant equipment outage configurations will not occur when specific plant equipment is out of service consistent with the proposed TS AOT change. An effective way to perform such an assessment is to evaluate equipment according to its contribution to plant risk (or safety) while the equipment covered by the proposed AOT change is out of service. Evaluation of such combinations of equipment out of service against the Tier 1 ICCDP acceptance guideline could be one appropriate method of identifying risk-significant configurations. Once plant equipment risk contribution is evaluated, an assessment can be made as to whether certain enhancements to the TS or procedures are required to avoid risk-significant situations. In addition, compensatory actions that can mitigate any corresponding increase in risk, (e.g., backup equipment, increased surveillance frequency, or upgrading procedures and training) should be used to offset the risk associated with certain configurations. These compensatory actions should have been evaluated and incorporated into the first tier where practical to do so. In addition, the review of Tier 2 for TS changes should ensure that the guidance contained in Regulatory Position 2.3.6 of Regulatory Guide 1.177 is met. c. Tier 3: Risk-Informned Configuration Risk Management for TS AOT Changes Tier 3 focuses on licensee programs that ensure that the risk impact of out-of-service equipment is appropriately evaluated prior to and while performing any maintenance activity. A viable program is able to uncover risk-significant plant equipment outage configurations in a timely manner during normal plant