Document: NUREG-0800
Document ID: d5452e7b-1e61-498b-9e3d-71073b3328ef
Document Type: srp
Title: LEAK-BEFORE-BREAK EVALUATION PROCEDURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0302/ML030280295.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.3
CFR Part: 
CFR Title: 

Content:
leak detection capability when the pipes are subjected to normal operating loads. If auxiliary leak detection systems are relied on, they should be described. For the estimation of leakage, the normal operating loads (i.e., deadweight, thermal expansion, and pressure) are to be combined based on the algebraic sum of individual values. e. Using fracture mechanics stability analysis or limit load analysis based on (1.) below, and normal plus SSE loads, determine the crit ical crack size for the postulated throughwall crack. Determine crack size margin by comparing the selected leakage size crack to the critical crack size. Demonstrate that there is a margin of 2 between the leakage and critical crack sizes. The same load combination method selected in (f.) below must be used to determine the critical crack size. f. Determine margin in terms of applied loads by 3 crack stability analysis. Demonstrate that the leakage size cracks will not experience unstable crack growth if 1.4 times the normal plus SSE loads are applied. Demonstrate that crack growth is stable and the final crack is limited such that a double-ended pipe break will not occur. However, the 1.4 margin can be reduced to 1.0 if the deadweight, thermal expansion, pressure, SSE (inertial), and seismic anchor motion (SAM) loads are combined based on individual absolute values as follows: F Combined = F Deadweight I + IF ThermalI + IF PressureI + IFS SEI+ IF SAMI W, OCombined z (Mj)DEadweighti + I(MOiThermaljl +I(Mi )Pressurej + I(M OSSEI + I(Mi)SAMI "(M)Combined = (M1)Combined + (M2)Combined + (ý24ombined where F denotes the axial force, M. denotes the i-th component of moment (i = 1, 2, 3), M denotes the ýotal moment, and the subscripts denote the load. An evaluation of seismic anchor motion loads at SSE conditions may be omitted when these are shown to be small at OBE conditions. 3.6.3-5 g. The piping materials toughness (J-R curves) and tensile (stress strain curves) properties should be determined at