Conservatism on current leak-before-break application
- Korea Atomic Energy Research Inst., Daejon (Korea, Republic of). Mechanical Systems Engineering Group
- SungKyunKwan Univ., Suwon (Korea, Republic of). Dept. of Mechanical Engineering
Currently, LBB (Leak Before Break) analysis is performed in accordance with the NUREG 1061 Vol. 3. According to NUREG 1061 Vol. 3, it is necessary to hypothesize the leakage crack at critical locations of a piping system. The leakage crack length is calculated by applying a margin of 10 on the capability of the plant leak detection system. Then the stability of the cracked pipe must be assured for normal plus SSE(Safe Shutdown Earthquake) loads at twice the leakage crack length, and {radical}2 times the sum of normal plus SSE loads at the leakage crack length. This current LBB criteria is very conservative. In this paper, the results of various studies are presented to demonstrate the conservatism on the current LBB application. The studies are focused on the plant in service inspection program, fatigue crack growth behavior of the crack, elastic plastic behavior of the cracked pipe considering entire piping geometry and also focused on the collection of material test data. In conclusion, it is demonstrated that some level of margins already exist in the standard LBB analysis method. Therefore, the margins specified in the NUREG 1061 Vol.3 could be relaxed to extend LBB application to the smaller diameter pipe.
- OSTI ID:
- 136777
- Report Number(s):
- CONF-950740-; ISBN 0-7918-1344-4; TRN: 96:000926
- Resource Relation:
- Conference: Joint American Society of Mechanical Engineers (ASME)/Japan Society of Mechanical Engineers (JSME) pressure vessels and piping conference, Honolulu, HI (United States), 23-27 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of International pressure vessels and piping codes and standards. Volume 1: Current applications; PVP-Volume 313-1; Rao, K.R.; Asada, Yasuhide; Brown, J. [eds.] [and others]; PB: 469 p.
- Country of Publication:
- United States
- Language:
- English
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