Annual report of JMTR, No.17, FY2002; April 1, 2002 - March 31, 2003

Department of JMTR

During the FY2002 (April 2002 to March 2003), the Japan Materials Testing Reactor (JMTR) was operated in three operation cycles for studies on the irradiation-assisted stress corrosion cracking (IASCC) of internal structures of light water reactors, development of the fusion blanket, basic materials research, radioisotope production, and so on. The reactor was twice subjected to unscheduled shutdowns, once due to an error signal of the control-rod drive mechanism and afterwards due to leakage of primary coolant. Recovery and corrective actions were taken properly, such as improvements in related facilities and revision of operation manuals. Besides, the beryllium reflector frames were replaced, which are internal structures of the JMTR. Concerning development on techniques for irradiation utilization, noticeable progress was made in an evaluation method of neutron and -ray heating rates of materials in JMTR irradiation, in development and installation of a monitoring and control system of specimen temperatures for IASCC irradiation examinations, and in successful performance tests by a post-irradiation crack-growth testing device, which brought a prospect of comparative studies between in-situ and post-irradiation examinations. In studies on the fusion blanket, a basic process was established for production of tritium breeder pebbles, and irradiation techniques were developed for in-pile functional tests of a simulated blanket module. In addition, joint seminars were held with the Korea Atomic Energy Research Institute (KAERI) on techniques for irradiation and post-irradiation examinations. The present report summarizes the JMTR operation and related technical development in the Department of JMTR during the FY2002.