Effects of Proton Irradiation on Reactor Pressure Vessel Steel and Its Model Alloys

Abstract

Effects of proton irradiation on the reactor pressure vessel steel (RPVS), A533B cl. 1 have been investigated by means of positron lifetime and Vickers hardness measurement in comparison with those of the iron-copper model alloys. The specimens were irradiated with 1 MeV proton up to a fluence of 3 × 1017 ions/cm2 (0.2 dpa, displacement per atom, at a peak) at temperature below 80°C. The recovery behavior of the irradiation effects was also investigated during isochronal annealing for 30 min with a 25°C step from 100°C to 650°C. By positron annihilation technique, it was recognized that microvoids, which consist of about 5 vacancies with the number density of the order of 1016 /cm3, were formed by the irradiation. The number of microvoids decreased after a low temperature annealing and completely annihilated at 250°C, although irradiation hardening still remained. A large portion of the hardening recovered by the annealing up to 300°C and almost annealed out at 450°C. Irradiation response and its recovery behavior of A533B RPVS were discussed compared to the result of Fe-based model alloys.

Positron Annihilation Study of RPV Steels Radiation Loaded by Hydrogen Ion Implantation

“…Therefore, the small recovery observed in the temperature interval of 200–300 °C could be explained by the decomposition of the small carbon-vacancy pairs or complexes. These findings correspond well with the available literature, where various authors note that the dissolution of vacancy complexes occurs at this temperature range in steels and Fe-C alloys [ 108 , 109 , 110 , 111 ]. However, this phenomenon of annealing CV complexes probably does not play a key role in terms of lattice recovery of VVER RPVs after irradiation because of the normal operating temperature (270–300 °C), and therefore it is expected that those types of defects will recombine shortly after their origin.…”

Effect of Ion Irradiation on the Mechanical Properties of High and Low Copper

“…Further study conducted by Shibamoto et al also suggests that hardening is caused by copper clustering in the matrix, and that nickel additions contribute to this mechanism. Their work agrees that Frenkel pairs increase hardening; however, they also suggest that after annealing above 400 o C, microvoids are no longer a cause of hardening, as they disappear above 200 o C [7].…”

Characterization of proton irradiation-induced defect in the A508-3 steel by slow positron beam

“…Migration of these clusters takes place in the temperature range (230-330°C), which is around the room temperature, namely the irradiation temperature of this study. Shibamoto et al [23] detected microvoids consisting of five vacancies at a number density of the order of 10 16 n/cm 3 in A533B steel irradiated with 1 MeV proton up to of 3 Â 10 17 ions/cm 2 (0.2 dpa, at a peak) at temperature below 80°C. Manganese atoms play an important role to suppress the growth of the microvoids through trapping vacancies by formation of Mn-V pairs and small Mn-V N clusters, which become unstable above 200°C [24].…”