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:
surement 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 candidate piping systems is very low. Water hammer is a generic term, which includes various unanticipated high frequency hydrodynamic events such as steam hammer and water slugging. To demonstrate that water hammer is not a significant contributor to pipe rupture, reliance on historical frequencies of water hammer events in specific piping systems coupled with reviews of operating procedures and conditions may be used for this evaluation. Alternatively, design changes such as the use of J-tubes, vacuum breakers, and jockey pumps coupled with improved operating procedures can be used to reduce concerns from water hammer. The reviewer should establish that any measures needed to abate water hammer frequency and magnitude will be effective for the life of the plant. 6. The reviewer should verify that the candidate piping is not susceptible to creep and creep-fatigue. Operation below 700EF in ferritic steel piping and below 800EF in austenitic steel piping can alleviate concerns of creep. 7. The reviewer should evaluate the corrosion resistance of piping, which can be demonstrated by the frequency and degree of corrosion in the specific piping systems. Modifications to operating conditions (e.g., controlling water chemistry) or design changes (e.g., replacing piping material) are measures that can be taken to improve corrosion resistance in piping. The reviewer should recognize that remedial residual stress improvement treatments are effective in reducing susceptibility to stress corrosion cracking. Other regulatory guidance on LBB specifies that two mitigation methods are 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