Document: NRC Regulatory Guide
Document ID: 6f84e3bf-9ff3-49fb-a16a-0de3b89e6bc6
Document Type: regulatory_guide
Title: An Approach for Plant-Specific Risk-Informed Decisionmaking for Inservice Inspection of Piping (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2103/ML21036A105.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.178
CFR Part: 
CFR Title: 

Content:
r proposed inspection intervals and scope to the NRC before implementation of the RI-ISI program at the plant. For piping segments categorized as safety significant that were the subject of a previous NRC-approved relief request or were exempt under existing ASME BPV Code, Section XI, criteria, the licensee should assess the appropriateness of the relief or exemption in light of the risk significance of the piping segment. 3.2 Performance Monitoring 3.2.1 Periodic Updates The RI-ISI program should be updated at least on the basis of periods that coincide with the inspection program requirements contained in ASME BPV Code, Section XI, under Inspection Program B. These updates should be performed more frequently if dictated by any plant procedures to update the PRA (which may be more restrictive than a Section XI period-type update) or as new degradation mechanisms are identified. RG 1.178, Page 20 3.2.2 Changes to Plant Design Features As changes to the plant design are implemented, changes to the inputs associated with RI-ISI program segment definition and element selections may occur. It is important to address these changes to the inputs included in any assessment that may affect resultant pipe failure potentials used to support the RI-ISI segment definition and element selection. Some examples of these inputs include the following: a. operating characteristics (e.g., changes in water chemistry control) b. construction and preservice examination results c. welding techniques and procedures d. stress data (operation modes, pressure, and temperature changes) In addition, plant design changes could result in significant changes to a plant’s CDF and LERF, which in turn could result in a change in consequence of failure for system piping segments. 3.2.3 Changes to Plant Procedures Licensees should include changes to plant procedures that affect ISI, such as system operating parameters, test intervals, or the ability of plant operations personnel to perform actions