Segregation and Precipitation on Dislocations in RPV Steels

The results of a series of different methods for estimating the solute concentration of copper-enriched precipitates and the solute segregation at dislocation in welds from the Midland and Palisades reactors were presented. These welds have been neutron irradiated to fluences of up to 3.4 times 10²³ n m^-2 (E > 1 MeV) at a temperature of 288degC. These methods include some variants of the maximum separation (or friends-of-friends) method, the tracer method, radial concentration profiles and the proxigram method. The results of these methods revealed that the estimate of the level of solute is strongly dependant on the precise definition of the location of the precipitate-matrix interface. The atom probe tomography (APT) studies have also demonstrated that the copper-enriched precipitates are preferentially located on the dislocation