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:
182 materials not be used in advanced pressurized water reactor plants and that, if an applicant wishes to use Alloy 82/182, that the applicant address the methods that will be used to mitigate PWSCC. These evaluations must demonstrate that PWSCC is not a potential source of pipe rupture. 4. The reviewer should evaluate the adequacy of the leakage detection systems associated with the reactor coolant system. Determination of leakage from a piping system under pressure involves uncertainties and, therefore, margins are needed. Sources of uncertainties include plugging of the leakage crack with particulate material over time, leakage prediction, measurement techniques, personnel, and frequency of inspections. Leakage detection systems are evaluated to determine whether they are sufficiently reliable, redundant, and sensitive so that a margin on the detection of unidentified leakage exists for through-wall flaws to support the deterministic fracture mechanics evaluation. The specifications for plant-specific leakage detection systems inside the containment should be equivalent to those in RG 1.45, “Reactor Coolant Pressure Boundary Leakage Detection Systems.” Application of LBB to piping systems outside containment would require that the applicant demonstrate that leakage detection 3.6.3-6 Revision 1 - March 2007 system are available that provide equivalent reliability, redundancy, and sensitivity to systems. RG 1.45 provides guidance on the capability of the leakage detection systems. Leak detection methods that have been shown to be acceptable include local leak detection, for example, visual observation or through leak detection instrumentation. Unless a detailed justification that accounts for the effects of these sources of uncertainties in the leakage measurement can be presented, a margin of 10 on the predicted leakage rate will be required for determining the leakage size flaw. 5. The reviewer should verify that the potential for water hammer in the