Performance evaluation of EPDM at elevated temperature

In Japanese BWR utilities, silicone rubber (VMQ) or fluoro rubber (FKM) has been used as a sealing material for the PCV upper flange and so on. However, these materials are not suitable for such use under the combined conditions of high-temperature steam and high-radiation dose by severe accident, so there is a possibility to reduce the sealing function that leads to a PCV flange leakage. Therefore, in the BWR plant owners recently decided to adopt an an 'improved EPDM' which has excellent characteristics against high-temperature and high-radiation emission conditions as the sealing material for the PCV upper flange. In this paper, we explain the result of the compression set test and the leakage test using a small flange simulating the actual PCV upper flange under high temperature condition up to 300degC. (author)