Small-angle neutron scattering of low-Cu RPV steels neutron-irradiated at 255 degrees C and post-irradiation annealed at 290 degrees C


Small-angle neutron scattering of low-Cu RPV steels neutron-irradiated at 255 degrees C and post-irradiation annealed at 290 degrees C

Wagner, A.; Bergner, F.; Ulbricht, A.; Dewhurst, C. D.

Fast neutron irradiation of low-Cu reactor pressure vessel (RPV) steels gives rise to the formation of solute clusters and a degradation of mechanical properties. A remarkable acceleration of cluster formation was identified in a previous investigation of low-Cu steels irradiated at 255 degrees C. The thermal stability of the observed features at a typical RPV operation temperature (290 degrees C) is of particular interest. Small-angle neutron scattering experiments for three low-Cu materials irradiated at 255 degrees C and exposed to post-irradiation annealing at 290 degrees C are reported. The results indicate stability of the irradiation-induced features at a temperature of 290 degrees C for all three materials. In two cases, even an increase in scattering intensity upon post-irradiation annealing has been observed. The effect of the annealing treatment on the nature of clusters is discussed and a model of the cluster-matrix interface is introduced to rationalize the observed increase in scattering intensity. The role of the residual elements is discussed.

Permalink: https://www.hzdr.de/publications/Publ-18492
Publ.-Id: 18492