Structural integrity of light water reactor pressure boundary components

Experiments that simulate a flaw embedded in the clad layer of irradiated RPV steel have identified the important material properties that control crack instability during transient conditions. Warm pre-stress effects were shown to strongly influence the effective fracture toughness performance of flawed structures. Its impact is important to the analysis of accident scenarios and to service life considerations. The first investigation into the effect of PWR environment in fatigue life of piping steels showed that the margin of safety offered by Section III of the ASME Code is nearly completely used up. The resulting data base can be used to formulate revisions to Section III which account for the fatigue behavior of piping steel in PWR environments. Completed studies of environmentally-assisted cracking under simulated crack-tip conditions show that a strong environmental component of the overall crack growth rate exists whenever manganese sulfide inclusions dissolve at the crack tip. This accounts for the evidence that many of the older reactor steels, with higher sulfide inclusion contents, exhibit elevated crack growth rates, near the ASME water environment reference line. Current work is organized into three major tasks: (1) fracture mechanics investigations, (2) environmentally-assisted crack growth in high temperature, reactor primary water, and (3) radiation sensitivity and postirradiation properties recovery