How to obtain a complete dependence curve of impact toughness or fracture toughness vs temperature on nuclear pressure vessel steels by using only one Charpy-size specimen

Abstract

Considering the re-utilization of parts of the broken Charpy-size specimens used in nuclear pressure vessel fracture toughness surveillance programs, this paper has investigated how to evaluate the dependence curve of impact toughness or fracture toughness vs temperature for a nuclear pressure vessel A508CL3 steel by using one standard Charpy-size specimen and the eight reconstituted Charpy-size specimens which are manufactured from the two broken halves of the tested standard Charpy-size specimen. The research results indicate that by this means a reliable and complete dependence curve of impact toughness or fracture toughness vs temperature on nuclear pressure vessel steels can be obtained by using only one standard Charpy-size specimen. This, in a nuclear surveillance program, is equivalent to getting the complete dependence curve of material property vs temperature from only one Charpy-size specimen that is taken out of a reactor core; this would be very valuable for improving the reliability of surveillance programmes on nuclear pressure vessel embrittlement due to neutron irradiation. Especially this method is extremely important for the life-time prediction and safety surveillance of a nuclear pressure vessel which has been operated for a long-time and for which there is left only a few surveillance specimens in it.