Program of in-pile IASCC testing under the simulated actual plant condition. Thermohydraulic design study of saturated temperature capsule for IASCC irradiation test

The advanced water chemistry controlled irradiation research device has been developed in JAERI (Japan Atomic Energy Research Institute) to perform irradiation tests for research on IASCC (Irradiation Assisted Stress Corrosion Cracking). This device is capable of carrying out the irradiation tests under the water chemistry and the temperature simulating the conditions for BWR core internals. The irradiation device consists of the SATCAP (Saturated Temperature Capsule) inserted into the JMTR (Japan Materials Testing Reactor) core and the water control unit installed out-of-core. Regarding the SATCAP, thermohydraulic design of the SATCAP was performed aiming at controlling the specimen temperature with high accuracy and increasing the flow velocity on the specimens' surface. As a result of studying the various capsule structures, a new type of the capsule with feedwater injection tube and thermal spacers with a rectangular hole was selected. It was found out that all temperature of the 78 specimens loaded in the space of 30 mm square section by 400 mm in length of the capsule was able to be controlled in the temperature range between 540 K and 560 K. (author)