Document: NRC Regulatory Guide
Document ID: 10f3c2aa-ada2-4132-8d49-7867458d81a7
Document Type: regulatory_guide
Title: Design Limits and Loading Combinations for Metal Primary Reactor Containment System Components + HISTORY - HISTORY 10/2006 – DG-1158 , Proposed Revision 1
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0630/ML063000278.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.57
CFR Part: 
CFR Title: 

Content:
l, and piping penetration assemblies,3 bellows-type expansion joints, and access openings. Piping, pumps, and valves that are defined as components of primary metal containment systems are constructed in accordance with the rules for either Code Class 1 or Code Class 2 components, as required by Article NE-1120. Any piping penetration assemblies or appurtenances that are not a part of the containment vessel should be constructed in accordance with the rules for Code Class 1 or Code Class 2 components, as required by the intended service function. 2 Refer to NCA-9200 of the Code for definitions of “parts” and “appurtenances.” 3 Penetration assemblies are parts or appurtenances that are required to permit piping, mechanical devices, and electrical connections to pass through the containment vessel shell or head and maintain leaktight integrity, while compensating for such things as temperature and pressure fluctuations and earthquake movements. DG-1158, Page 5 C. REGULATORY POSITION 1. Code Class MC vessels, electrical and mechanical penetration assemblies, and other penetration assemblies (excluding bellows-type expansion joints) that are parts or appurtenances of the vessel. For earthquake engineering criteria, 10 CFR Part 50, Appendix S, “Earthquake Engineering Criteria for Nuclear Power Plants,” would be applicable for the operating-basis earthquake (OBE) and safe-shutdown earthquake (SSE). In this manner, the OBE serves the function as an inspection-level earthquake below which the effect on the health and safety of the public would be insignificant and above which the licensee would be required to shut down the plant and inspect for damage. Code Class MC components of primary metal containment systems that are completely enclosed within Seismic Category I structures4 should be designed to withstand the following loads and loading combinations within the specified design limits. 1.1 Loads D -------Dead loads. L -------Live loads, including all loads