ケーブル絶縁材の健全性診断に向けた非破壊検査システム開発（３）
概要
We have researched radiation-induced deterioration behaviors of cable insulation materials used in nuclear power plants and a nondestructive inspection method to detect the behaviors in our past reports. The deterioration was generated by electron beam irradiation simulating gamma-ray irradiation in the field. As a result, we found it possible to detect the deterioration by comparing the natural frequencies of the cables before and after the irradiation through our original digital hammering inspection technology using AE sensor. In this report, the replaced cables used in an actual nuclear power plant for 30 years were irradiated and the effect of irradiation temperature was studied. The results indicated that the cables had almost the same durability against the irradiations at high temperatures and at room temperature. Moreover, we estimated the diagnostic reference value in the natural frequency by correlating the elongation at break acquired by tensile test and the frequency.
