Document: NUREG-0800
Document ID: 4e1d86bd-74a5-4678-8bc0-ffce3ba28ea0
Document Type: srp
Title: RISK-INFORMED INSERVICE TESTING
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0428/ML042880272.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.7
CFR Part: 
CFR Title: 

Content:
e's process on the determination of risk importance of components in the RI- IST program is robust in terms of the important PRA modeling techniques, assumptions, and data. In addition, the factors as described in the section on integrated decisionmaking (e.g., risk increases are small, defense in depth philosophy is maintained, and safety margins are maintained) are taken into account when categorizing a component as low safety significant. 7. Evaluating the Effect of Proposed Changes on Overall Plant Risk The reviewer verifies that sufficient information is provided to make the following findings: * The application is either risk neutral or decreases plant risk, or if an application results in an increase in risk, the increase is within the acceptance guidelines specified in Section 2.2.4 of Regulatory Guide 1.174 * In calculating the risk impact: 3.9.7-29 Rev. 0-August 1998 * Fault exposure time for IST components is modeled appropriately and is linked to programmatic activities. * The effects of aging and environmental stresses (time dependent degradation of the failure rates) has been addressed, either explicitly in the PRA models or as part of the licensee's integrated decisionmaking process. * The effects of the IST program change on initiating event frequency have been considered. * Common cause failure has been suitably addressed. The licensee has systematically identified all component groups sharing attributes that correlate with CCF potential and that affect IST, either in that they comprise IST components or compensating SSCs. The licensee's performance monitoring program addresses staggered testing of IST components in CCF groups. * Credit for human actions that compensate for relaxation of IST is modeled in a defensible way. * Appropriate failure rates have been used for IST components. Justification has been provided for the failure rates and monitoring will provide ongoing justification. The licensee has reviewed the modeling of compensating SSCs,