Document: NUREG-0800
Document ID: 0e333e1a-276a-43f1-b2ab-fdf1009c6f92
Document Type: srp
Title: Draft Revision 3 – August 2015
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1422/ML14227A646.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
CFR Part: 
CFR Title: 

Content:
y higher potential for failure, such that an adequate and practical level of protection may be achieved. Subject to certain limitations as delineated in Standard Review Plan (SRP) Section 3.6.3, 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 BTP 3-4-2 Draft Revision 3 – August 2015 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, a review of the piping layout and plant arrangement drawings should clearly show that the effects of postulated piping breaks at any location are isolated or are physically remote from essential systems