Document: NUREG-0800
Document ID: c6f58bab-ddce-42eb-a3ef-02dd3da952fc
Document Type: srp
Title: Revision 3 – December 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1608/ML16085A315.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
CFR Part: 
CFR Title: 

Content:
er potential for failure, such that an adequate and practical level of protection may BTP 3-4-2 Revision 3 –December 2016 be achieved. Subject to certain limitations as delineated in Standard Review Plan (SRP) Section 3.6.3, “Leak-Before-Break Evaluation Procedures,” GDC 4 allows dynamic effects associated with postulated pipe ruptures to be excluded from the design basis when analyses reviewed and approved by the Commission demonstrate that the probability of fluid system piping rupture is extremely low under design basis conditions. These analyses are commonly referred to as “leak-before-break” (LBB) analyses. The application of LBB to piping system design is reviewed in accordance with ---SRP Section 3.6.3. In 10 CFR Part 50, Appendix S, “Earthquake Engineering Criteria for Nuclear Power Plants,” the staff approves the elimination of the operating basis earthquake (OBE) in the design process of a plant when the OBE ground motion is less than or equal to one-third of the safe shutdown earthquake ground motion. Furthermore, no replacement earthquake loading should be used to establish the postulated pipe rupture and leakage crack locations once the OBE is eliminated from the design and that the criteria for postulating pipe ruptures and leakage cracks in high- and moderate-energy piping systems should be based on factors attributed only to normal and operational transients. However, for establishing pipe breaks and leakage cracks due to fatigue effects, calculation of the cumulative usage factor should continue to include seismic cyclic effects. B. BRANCH TECHNICAL POSITION 1. High-Energy Fluid Systems Piping (i) Fluid Systems Separated From Essential Systems and Components. For the purpose of satisfying the separation provisions of plant arrangement as specified in B.1.a of BTP 3-3, “Protection Against Postulated Piping Failures in Fluid Systems Outside Containment,” a review of the piping layout and plant arrangement drawings should clearly show