Analysis of Large-Scale Fracture Experiments Addressing the Behaviour of Sub-Clad Flaws in Reactor Pressure Vessel Steel

To investigate transferability of the Master Curve methodology to shallow, sub-clad flaws in reactor pressure vessel applications, a series of six fracture tests was performed on large-scale specimens, which were fabricated from grade A533 steel and contained simulated sub-surface defects. First of all, the paper briefly describes this four-point bend test programme. Further an in-depth analysis of the experiments is presented. Detailed finite element calculations are used to compare the fracture behaviour of the large-scale bend beams with the test material's standard Master Curve. The latter is obtained from dedicated laboratory experiments, also checking through-wall variation of brittle-to-ductile transition behaviour. This study confirms a significant constraint-loss effect related to the sub-clad defects, which is in line with findings from previous research projects.JRC.F.4-Safety of future nuclear reactor