Investigation and evaluation of ductile fracture behaviors in LWR piping under bending load

The Leak-Before-Break (LBB) concept has been recognized to be applicable to the LWR piping design based on more realistic subcritical crack growth, fluid leakage and fracture evaluation by the fracture mechanics methodology. In the mean time, some piping integrity research programs which are intended to validate or establish the LBB design criteria are also under way. At the JAERI, a ductile pipe fracture test program which is involved in the LWR piping reliability research program for demonstrating the integrity and safety of piping even under the postulated pipe break accident, has been conducted to provide the pipe fracture data base of austenitic stainless steel and carbon steel piping which may demonstrate the integrity in LWR piping and validate the LBB concept. This paper is concerned with the recent development of this program in which four-point bending tests have been carried out on 3-, 6- and 12-inch diameter pipes of type 304 stainless steel and STS42 carbon steel. (orig./HP)