Document: NUREG-0800
Document ID: a4232dd4-7548-4c1c-9a51-16dc766f1087
Document Type: srp
Title: Revision 2 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070800008.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
CFR Part: 
CFR Title: 

Content:
dynamic effects associated with postulated pipe ruptures to be excluded from the design basis when analyses reviewed and approved by the 1 Systems and components necessary to shut down the reactor and mitigate the consequences of a postulated pipe rupture without offsite power. 2 For those loads and conditions for which Level A and Level B stress limits have been specified in the design specification (including the operating basis earthquake). BTP 3-4-2 Revision 2 - March 2007 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 the ABWR and System 80+ design certification FSERs, the staff accepted an exemption to 10 CFR 100, Appendix A that the design of all safety-related SSCs consider operating basis earthquake (OBE) loads. In SECY 93-087, the staff recommended that the Commission approve the approach to eliminate the OBE from the design of SSCs. Furthermore, the Staff concluded that 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, the Staff concluded that calculation of the cumulative usage factor should continue to include seismic cyclic effects. B. BRANCH TECHNICAL POSITION A. 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 Branch Technical Position (BTP) 3-3, a review of the