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:
needed to address materials susceptible to an active stress corrosion cracking degradation mechanism. The reviewer would review such evaluations on a case-by- case basis. For example, in boiling water reactors (BWR) hydrogen water chemistry may be proposed as an additive measure with remedial stress improvement treatments. The licensees' or applicants’ practices with regard to BWR water chemistry would be an additional factor considered in the review. Non-conforming piping with planar flaws in excess of the standards in the ASME Code, Section XI, Tables IWB-3514-1 and -2, would not be permitted to be qualified for LBB approval. However, non-conforming piping that has been treated by two mitigating methods may qualify for LBB if the piping contains no flaws larger than those permitted by the ASME Code Section XI. The NRC is re-evaluating the position on mitigation measures and plans to revise SRP 3.6.3, as necessary, when the evaluation is completed. 8. The reviewer should assess the potential for indirect sources of pipe ruptures to ensure that indirect failure mechanisms defined in the plant SAR are negligible causes of pipe rupture. Compliance with the snubber surveillance requirements of the technical specifications ensures that snubber failure rates are acceptably low. 3.6.3-7 Revision 1 - March 2007 9. The reviewer should determine that the piping material will not become susceptible to brittle cleavage-type failures over the full range of system operating temperatures (that is, the material is on the upper shelf of the Charpy Impact energy versus test temperature curve). 10. The reviewer should determine that the candidate piping does not have a history of fatigue cracking or failure. An evaluation to ensure that the potential for pipe rupture due to thermal and mechanical induced fatigue is unlikely should be performed. Licensees and applicants must demonstrate that (a) adequate mixing of high and low temperature fluids occurs in the piping so that there is