Summary of the IAEA/CRP 3 fracture mechanical results

This report describes the re-evaluation of the IAEA/CRP 3 fracture mechanical results applying a statistical analysis method known as the VTT approach. It constitutes the final report for the IAEA contract 8251/RB, titled: ''Fracture Mechanics Analysis for Coordinated Research Programme on Optimizing of Reactor Pressure Vessel Surveillance Programmes and Their Analyses'', carried out at VTT Manufacturing Technology under the period 15.12.1994-20.10.1995. Based on the evaluation it can be concluded that direct determination of static fracture toughness describing brittle fracture is possible with small irradiated specimens, provided that the statistical analysis of the data, correcting for specimen size and applying the master curve, is performed. Lab-to-lab variations are generally within normal material scatter. Fracture toughness for ductile fracture initiation and crack growth resistance show much larger lab-to-lab variations and cannot presently be regarded as a reliable parameters. Dynamic fracture toughness testing in the programme was scarce, and no clear statement regarding the reliability of dynamic fracture toughness can be made. In all cases but one, the static fracture toughness shift was greater than or equal to the Charpy-V shift. Thus the Charpy-V test does not seem to be a good estimator of the materials irradiation response. In the future, more emphasis should be directed towards the direct measurement of the static fracture toughness.