Degradation of flame‐retardant ethylene‐propylene‐diene rubber by radiation and steam
Jiayi You, Hikaru Yamaguchi, Hiroyuki Ishii, Naoshi Hirai, Yoshimichi Ohki
Abstract
Safety‐related cables in nuclear power plants must be functional even during the occurrence of a severe accident. In this regard, flame‐retardant ethylene‐propylene‐diene rubber (FR‐EPR) widely used for electrical insulation in safety‐related cables was aged under several simulated severe accident conditions. Namely, 60 Co gamma rays were irradiated at two different dose rates to sheets of FR‐EPR at room temperature or 100°C. After that, saturated or superheated steam was exposed to several sheets at a constant temperature of 155 or 220°C, or at six stepwise elevating temperatures from 120 to 220°C. Various mechanical properties and complex permittivity were measured for these sheets. As a result, the effects of heat, gamma‐ray irradiation, and steam exposure on the degradation of FR‐EPR were clarified. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.