RADIATION EMBRITTLEMENT AND THERMAL ANNEALING BEHAVIOR OF CR-NI-MO REACTOR PRESSURE-VESSEL MATERIALS

The last generation of Russian type of reactor vessels (WWER-1000) is made of low alloy chromium-nickel-molybdenum steel. In order to study the radiation behavior of that steel, fourteen different materials, i. e. eight base metals and six weld metals, have been irradiated to diff erent fluences at 290 degrees C. The results of the corresponding Char py V-notch impact tests are represented in this article. Some results of tensile tests are also given. Emphasis is given to the roles of met allurgical variables and dose effect. The results indicate anomalous d ose dependence of irradiation-induced impact transition temperature sh ift. The corresponding trend curve has been proposed. Some of the irra diated materials have been subsequently annealed. It has been shown th at the restoration effectiveness of anneal increases with increasing a nnealing temperature from 400 to 490 degrees C, and nickel enhances re sidual shift after postirradiation annealing at 460 degrees C.