A study on irradiation conditions in LOCA simulation test by alternate exposure

LOCA tests are generally performed with specimens exposed alternately to radiation and vapor. This report particularly describes effects of the irradiation procedure in such tests. Nine samples of EPDM with different formulation ingredients are prepared and investigated. Instead of applying a long-term irradiation, samples are irradiated at high dose rates for short periods of time. Irradiation is conducted in an oxygen-rich environment at room temperature or in air at a high temperature so that oxidation takes place uniformly over a sample at a high dose rate. A tensile test is carried out in order to examine the mechanical properties of irradiated samples. Measurements of 100 % modulus, breaking extension and breaking strength are made and discussed. It is concluded that the above two sets of conditions can be used to carry out evaluation of deterioration in mechanical properties in a short period of time. (Nogami, K.)