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:
ive of plant practices (e.g., one-half of the CT). A-2.3.2 Maintenance Schedules and Frequency Maintenance schedule and frequency data include the maintenance scheduling used by the plant for defining the situations in which multiple equipment or system trains may be taken down for PM. These schedules are important to ensure that high risks from components being down simultaneously, implicitly allowed by the TS change, do not occur. The maintenance frequency or frequency of downtime for a component may be from 3 to 10 times higher than the failure frequency. Since CTs can be used for maintenance, the frequency of maintenance should be incorporated in estimating the downtime frequency. A-2.3.3 Data Relating to Component Testing The following data related to component testing, in addition to those available as part of the PRA study, form part of a TS change evaluation relating to surveillance requirements: a. The evaluation should list the components being tested, any component realigned from the safety position during a test, the duration of the test, and the test frequency recommended by the manufacturer. b. The evaluation should include the efficiency of the test (i.e., the failure modes detected by the test with regard to aspects such as components and support system interfaces). Bounding assumptions can be made if obtaining detailed data or related information is costly. c. The analyses should account for any potential negative effects of surveillance testing (e.g., that may cause the potential for introducing plant transients or that may cause unnecessary wear of the equipment). Preliminary evaluations can be used to determine the need for a more detailed analysis. DG-1287, Appendix A, Page A-9 d. The evaluation should state the test strategy used for the redundant components in a system (i.e., whether staggered or sequential testing is performed). The standard PRA quantification assumes that components follow no specific schedule and are randomly placed.