Effect of Pipe Size on the Leak-Before-Break Recommended Safety Margins in a Typical Pressurized Water Reactor
- Westinghouse Nuclear Services Business Unit, 4350 Northern Pike, Monroeville (United States)
NRC regulations require that nuclear power plants be designed and built to shut down safely in the event of a sudden pipe break. The leak-before-break (LBB) methodology is accepted as a technically justifiable approach for eliminating postulation of double-ended guillotine break (DEGB) in high energy piping systems. This is the result of extensive research, development, and rigorous evaluations by the NRC and the commercial nuclear power industry since the early 1970's. The DEGB postulation is responsible for the hundreds of pipe whip restraints and jet shields found in commercial nuclear plants. These restraints and jet shields not only cost many millions of dollars to design and construct, but also cause plant congestion leading to reduced reliability in in-service inspection and increased man-rem exposure. The LBB applications gathered momentum since the latter part of the 80's. The benefits of LBB are multi-fold with the maximum benefits derived based on the extent of LBB applications. While the LBB has been applied to many large diameter piping systems, it is highly desirable to extend the applications to other smaller diameter high energy piping systems. However, it is intuitively obvious that demonstration of all the recommended LBB safety margins becomes increasingly difficult as the pipe size under consideration is reduced. In this paper an attempt is made to quantify the pipe size effect on the safety margins investigating the level of difficulty. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 21016386
- Country of Publication:
- United States
- Language:
- English
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