Document: NUREG-0800
Document ID: dac334d4-585f-42f5-bde4-118e876f5d4c
Document Type: srp
Title: PIPING SYSTEMS AND COMPONENTS (Tier 1)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070660.pdf
Revision Date: 2023-06
Chapter: 14
Section ID: 14.3.3
CFR Part: 
CFR Title: 

Content:
may be verified by either a generic piping design ITAAC as described above, or by each system ITAAC. The use of other codes and standards (e.g., AISC Steel Construction Manual for building structural steel) are considered within the Tier 2 scope, and the DCD Tier 2 contains descriptions of the applicable codes and standards for these other safety-related structures, systems, and components that are not designed to the ASME Boiler and Pressure Vessel Code, Section III. FABRICATION (WELDING) General Design Criterion 14 of 10 CFR Part 50, Appendix A requires that the reactor coolant pressure boundary be designed, fabricated, erected, and tested so as to have an extremely low probability of abnormal leakage. In addition, General Design Criterion 30 requires that components which are part of the reactor coolant pressure boundary be designed, fabricated, erected, and tested to the highest quality standards practical. DRAFT Rev. 0 - April 1996 14.3.3-6 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. Nuclear power plant components classified as Quality Groups A, B, and C are required by 10 CFR 50.55a to meet the requirements for ASME Code Classes 1, 2, and 3, respectively. In each system description, the functional drawing identifies 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, and 3 structural welds (e.g., pipe support welds) are not included within Tier 1 scope because they were deemed to be indirectly involved in preventing or mitigating an accident or event (e.g., Pipe supports provide protection of the piping; but, it is the piping itself that is needed for accident mitigation). Thus, ASME Code Class 1, 2, and 3 structural welds are included in the Tier 2 scope. The