A COMPREHENSIVE STUDY OF RELATIONSHIP BETWEEN MAGNETIC HYSTERESIS PROPERTIES AND IRRADIATION EMBRITTLEMENT IN NUCLEAR REACTOR PRESSURE VESSEL STEELS

Satoru Kobayashi – Hiroaki Kikuchi – Seiki Takahashi – Yasuhiro Kamada

   We report results of measurements of magnetic minor hysteresis loops for neutron-irradiated A533B-type nuclear reactor pressure vessel (RPV) steels with varying alloy composition and irradiation condition. A minor-loop coefficient, which is obtained from a scaling power law between minor-loop parameters shows a steep decrease just after irradiation, followed by a maximum in the intermediate fluence regime for most investigated alloys. This behavior is largely different from that obtained previously for RPV steels with a different initial microstructure. The results were explained by a model analysis assuming Avrami-type growth for Cu-rich precipitates and an empirical logarithmic law for relaxation of internal stress.

Keywords: neutron irradiation embrittlement, magnetic hysteresis, Cu precipitate, scaling analysis, pressure vessel steel

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