BR2 irradiations in support of enhanced surveillance of nuclear reactor pressure vessels

An enhanced reactor pressure vessel surveillance technology i sbeing developed in Belgium. The aimis to dtermine in-service shifts of static initiation fracture toughnes in a more direct and precise manner than possible through the current indexation procedure to the CNV impact test. The technology entails the reconstitution, precracking and slow bend testing of broken CVN remnants, and emphasizes the maximization of information by combining static tensile and CVN load-dislocation theory and micromechanical modelling provide the interpretation tools allowing to justify plant-specific embrittlement trend curves. This enhanced surveillance technology is being actively validated. An important component in this effort is the BR2/Chivas Accelerated Irradiation and Testing Programme, summarized in this paper. The results of the first irradiation to 5 E19 cm-2(> 1MeV, nominal) at a temperature of 290°C are presented, as well as preliminary data from an irradiation to the same fluence at 260°C. The lower temperature was selected to match the operation temperatures of the recently samled BR3 and Chooz-A vessels; the results obtained by BR2/CHIVAS exposure of BR3 base metal specimens will be compared to the results from the vessel testing programme.