DETERMINATION OF LIMITS FOR SMALLEST DETECTABLE AND LARGEST SUBCRITICAL LEAKAGE CRACKS IN PIPING SYSTEMS

Nuclear power plant piping systems - those still in their original as- built condition as well as upgraded designs - are subject to safety an alysis. In order to limit the consequences of postulated piping failur es, the basic safety concept incorporating rupture preclusion criteria is applied to specific high-energy piping systems. Leak-before-break analyses are also conducted within the framework of this concept. Thes e analyses serve to determine the potential consequences of jet and re action forces due to maximum subcritical leakage cracks while also est ablishing the minimum crack sizes that would be reliably detectable by the leakage rates resulting from these cracks. The boundary condition s for these analyses are not clearly defined. Using various examples a s a basis, this paper presents and discusses how the leak-before-break concept can be applied.