Document: NUREG-0800
Document ID: 9e12eef7-842c-43db-9170-12cf365ca8b9
Document Type: srp
Title: PIPING SYSTEMS AND COMPONENTS - INSPECTIONS, TESTS, ANALYSES,
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070660622.pdf
Revision Date: 2023-06
Chapter: 14
Section ID: 14.3.3
CFR Part: 
CFR Title: 

Content:
reactor coolant pressure boundary be designed, fabricated, erected, and tested to the highest quality standards practical. The ASME Code class welds are included in Tier 1 because the ASME Boiler and Pressure Vessel Code, Section III is referenced in 10 CFR 50.55a, which requires nuclear power plant components classified as Quality Groups A, B, and C to meet ASME Code Class 1, 2, or 3 requirements, respectively. In each system description, the functional drawing shows the boundaries of the ASME Code classification. The integrity of the pressure boundary is required to be maintained because it is directly involved in preventing or mitigating an accident or event under the defense-in-depth principle. ASME Code Class 1, 2, or 3 structural welds (e.g., pipe support welds) are not within Tier 1 scope because they indirectly prevent or mitigate accidents or events (e.g., pipe supports protect the piping but the piping itself is needed for accident mitigation). Thus, ASME Code Class 1, 2, or 3 structural welds are in the Tier 2 scope. The integrity of the pressure boundary in the plant will be ensured, in part, through a verification of the welding quality. This verification is performed as a part of the basic configuration ITAAC of each specific system. The basic configuration ITAAC, one of the standard ITAAC listed in SRP Section 14.3, Appendix D, is required for most systems in Tier 1. The provisions of the basic configuration check that must be specified in Tier 1 include non-destructive examination of the as-built pressure boundary welds for the ASME Code Class 1, 2, or 3 SSCs in the design description. The acceptance criteria for the welds are the ASME Code, Section III weld examination requirements. The specific weld examination requirements for a particular ASME Code Class 1, 2, or 3 component and weld type are tabulated in Tier 2. The specific weld examination requirements are considered Tier 2 because they could change depending on future revisions to the ASME