RPV fracture toughness of various metallurgical zones at very high fluences
Résumé
The monitoring and assessment of aging effects of reactor pressure vessels (RPV) of PWRs during operation life is performed by means of an irradiation surveillance program. In the surveillance pro-gram of the PWRs of the French fleet, a large database of Charpy transition shifts and fracture toughness has been established up to neutron fluence values corresponding to 40 years of operation and over, for the base metals, welds and Heat Affected Zones (HAZ) of the core zone. Much fewer fracture toughness data are nevertheless available for relevant materials at higher fluence values, es-pecially for underclad heat affected zones (UHAZ) that are not monitored by the irradiation surveil-lance program. This paper presents the RandD program carried out by CEA, EDF and FRAMATOME in order to provide fracture toughness data to complement the irradiation surveillance program in a higher fluence range and including samples of underclad heat affected zones. The irradiation expo-sure of this program was performed in OSIRIS reactor at CEA Saclay up to a maximum fluence level of 14 10$^{19}$ n/cm$^2$ (E > 1MeV). Fracture toughness properties were characterized for two base metals, a fine grain a coarse grain HAZ and a weld metal with Pre-cracked Charpy V (PCCV) specimens. The fracture toughness data were analyzed with the Master Curve methodology and compared to the RCC-M lower bound curve
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