SEDL / STP / STP1475-EB / STP37585S

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

Shibamoto, H
Japan Nuclear Cycle Development Institute, Ibaraki,

Kimura, A
Professor, Institute of Advanced Energy, Kyoto University, Kyoto,

Hasegawa, M
Professor, Institute for Materials Research, Tohoku University, Sendai,

Matsui, H
Professor, Institute for Materials Research, Tohoku University, Sendai,

Yamaguchi, S
Professor, Chiba Institute of Technology, Narasino-city, Chiba,

Pages: 8    Published: Jan 2006

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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.