Abstract
The investigation was undertaken to evaluate the deterioration and the residual life time of O-ring which had been used for 13 years in nuclear reactor. Three O-ring made of silicone which was used for sealing between pressure vessel and “In reactor tube”.
The applied aging factors to the O-rings were estimated by simulation and/or caluculation. Dose was 3.46kGy for the highest sample, temperature was 50°C during on powered, but the sliding friction applied to O-ring was estimated to be a small.
The same type of O-ring as that used in the pressure vessel was irradiated, dose rate was 5.0kGy/h at 70°C for the short time test. The relationship between the changes in mechanical properties of samples and dose was studied. It was found out that more than ten times of dose was necessary to give the same deterioration as that of the O-rings used in pressure vessel.
Referring to data obtained, the O-rings are considered to be able to use until their ultimate elongation go down to 50% and the residual life time of the O-rings was predicted to be 26 years.