Papers by Keyword: Irradiation Induced Defects

Abstract: The irradiation effects of a new nickel-base alloy (Ni-17Mo-7Cr) has been investigated by using 1 MeV Xe²⁰⁺ and 7 MeV Xe²⁶⁺ ions irradiation with displacement damage range from 0.33 to 6.6 dpa. The transmission electron microscopy and nanoindentation were employed to study respectively the microstructural evolution of thin-foil specimens and nanoindentation hardness changes of bulk specimens. In case of 0.33 dpa, high number density of nano-scale black spots were observed in thin-foil specimens. High-resolution transmission electron microscopy images revealed that these black spots are some rounded solute clusters and dislocation loops. As far as the ion dose of 3.3 and 6.6 dpa, the black spots were replaced with linear-like defects which were proved to be some Ni, Mo and Cr-enrichment regions. In addition, nanoindentation results for bulk specimens showed an evident hardening phenomenon in irradiated Ni-17Mo-7Cr alloys, compared to the unirradiated specimen. The irradiation induced defects may be responsible for the hardening of Ni-17Mo-7Cr alloys.

Abstract: The irradiation induced defects of irradiated reactor pressure vessel(RPV) steel were investigated by a small angle neutron scattering. The degradation of the mechanical properties of RPV steels during an irradiation in a nuclear power plant is closely related to the irradiation induced defects. The size of these defects is known to be a few nanometers, and the small angle neutron scattering technique is regarded as the best non destructive technique to characterize the nano sized inhomogeneities in bulk samples. The RPV steel was irradiated in the HANARO reactor in KAERI. The small angle neutron scattering experiments were performed at SANS instrument in the HANARO reactor. Both unirradiated and irradiated RPV steels were measured and the SANS data of both steels were compared. The nano sized irradiation induced defects were quantitatively analyzed by SANS. The type of defects was also analyzed based on the SANS results, and the effect of the chemical composition of the RPV steel on the irradiation induced defects was discussed.