Capsule irradiation techniques in JMTR

The Japan Material Testing Reactor in the Japan Atomic Energy Research Institute is the largest reactor exclusively used for irradiation in Japan, and it has developed the irradiation techniques meeting various irradiation needs accompanying the advance of atomic energy development and the expansion of the techniques of atomic energy utilization. In this paper, the present status of the JMTR is reported about the measurement of irradiation temperature, control techniques, in-core creep testing techniques, rapid temperature raising techniques, the actual example of capsule irradiation test and so on as the fundamental problems in the irradiation using a nuclear reactor. The JMTR has been utilized for the irradiation test of the fuel and materials for nuclear reactors and the production of RIs. The thermal output is 50 MW, and the operation of yearly 4 or 5 cycles has been carried out, making the operation for 22 days as one cycle. In the JMTR, as the large irradiation facilities, there are the water loop (OWL-2), the gas loop (OGL-1) and the rapid power raising test equipment (BOCA-OSF-1), and for irradiating on relatively small specimens, there are the hydraulic rabbit irradiation equipment and the capsule irradiation equipment. At the time of irradiation, the safe operation of the reactor must not be affected. (Kako, I.)