Document: NUREG-0800
Document ID: 22c713a3-851c-4195-8d52-e7a90bcbeed0
Document Type: srp
Title: LEAK-BEFORE-BREAK EVALUATION PROCEDURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600396.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.3
CFR Part: 
CFR Title: 

Content:
also be conducted at a lower temperature, which may represent a plant condition (e.g., hot standby) where pipe break would present safety concerns similar to normal operation. These tests are intended only to determine if there is any significant dependence of toughness on temperature over the temperature range of interest. The lower toughness should be used in the fracture mechanics evaluation. One J-R curve and one stress- strain curve for one base metal and weld metal are considered adequate to determine temperature dependence. (C) Analysis (i) Demonstrate the accuracy of both the fracture mechanics and the leak rate computational methods by comparison with other acceptable computational procedures or with experimental data. (ii) Specify the type and magnitude of the loads applied to the piping system (forces, bending and torsional moments), their sources (thermal, deadweight, seismic, and seismic anchor movement), and method of combination. For each pipe size in the piping system, identify the location(s) that have the least favorable combination of stress and material properties for base metal, weldments, nozzles, and safe ends. (iii) Postulate a throughwall flaw at the location(s) specified in subparagraph 11.(C)(ii) above. The size of the flaw should be large enough so that leakage from the flaw during normal operation would be 10 times greater than the minimum leakage the detection system is capable of sensing. 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 and applied to the leakage flaw size. 3.6.3-9 Revision 1 - March 2007 (iv) Using fracture mechanics stability analysis or limit load analysis based on subparagraph 11(C)(vi) below, determine the critical crack size for the postulated throughwall crack using loads from the normal plus safe shutdown