A new approach for evaluating radiation embrittlement of reactor pressure vessel steels

A new approach is developed to predict the radiation embrittlement of reactor pressure vessel steels. The Charpy transition temperature shift data contained in the Power Reactor Embrittlement Database is used in this study. The results indicate that this new embrittlement predictor achieved about 67.3% and 52.4% reductions respectively, in the uncertainties for General Electric (GE) Boiling Water Reactor plate and weld data compared to Regulatory Guide 1.99, Rev. 2 (RG1.99/R2). The implications of irradiation temperature effects for the development of radiation embrittlement models are then discussed. A new approach for the Charpy trend curve is also developed, which incorporates the chemical compositions into the governing fitting equation. This approach reduces the uncertainty of Charpy data fitting and provides an expedient scheme to link and project the surveillance test results to those for reactor pressure vessel steels.