Review of work related to ‘leak-before-break’ assessment

Over recent years the concept of leak-before-break (LBB) has been considered in establishing safety cases for piping particularly for the nuclear industry. The LBB concept is viewed as a more realistic design criterion in the design of high energy fluid piping as compared with the double-ended guillotine break as a design criterion, which gives rise to many problems. The concept of LBB aims at the application of fracture mechanics to demonstrate that pipes are very unlikely to experience sudden, catastrophic break without prior indication of detectable leakage. This report is intended to give a review of LBB research activities that have been or are being conducted throughout the world on the basis of literature published up to 1990. Its introduction deals with the background, approach and limitations of LBB. A review of research work related to LBB gives details of nuclear piping studies carried out in different countries. At the end of the paper, some of the future work proposed to be undertaken in the field is described.