Westinghouse Nuclear Europe reactor vessel surveillance program

Westinghouse's basic philosophy as to reactor vessel material radiation can be summarized as follows: a) Sufficient data are provided to assess the margin for continued safe operation of the plant. b) Sufficient data are provided to set the heatup-cooldown limitation curves. c) Data are provided to perform a quantitative assessment of reactor vessel integrity. d) Sufficient capsules are provided to develop trend in the irradiation damage and provide sufficient samples for annealing if required. The available data are evaluated in terms of current regulatory rules and guides, and copper-fluence trend curves. In addition, data from accelerated irradiation test programs are reviewed in terms of post-irradiation annealing parameters. The results to date indicate that after a fluence of 3x109 n/cm2 the reactor vessel materials studied exhibited fracture toughness sufficiently high for continued safe operation of the nuclear power plants. (author)