Current status toward the reoperation of JMTR

Kaminaga, Masanori; Tanimoto, Masataka; Ooka, Makoto; Ishihara, Masahiro; Kusunoki, Tsuyoshi; Komori, Yoshihiro; Suzuki, Masahide

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The Japan Materials Testing Reactor (JMTR) in Japan Atomic Energy Agency (JAEA) is a light water cooled tank type reactor with 50 MW thermal power. From its first criticality in March 1968, the JMTR has been utilized for fuel/material irradiation examinations of LWRs, HTGR, fusion reactor as well as for RI productions. In August 2006, the JMTR operation was once stopped in order to have a check & review for the reoperation which was discussed by internal as well as external committees. As a result of the national discussion, the JMTR was determined, finally, to restart after necessary refurbishment works. The refurbishment was started from the beginning of JFY 2007, and replaced were motors of primary and secondary cooling pumps, nuclear instrumentation system, process control system, safety protection system and so on. The refurbishment was finished in March 2011 taking four years as planned schedule. Unfortunately, at the end of the JFY 2010 on March 11, the Great-Eastern-Japan-Earthquake occurred, and functional tests before the JMTR restart, such as cooling system, reactor control system and so on, were delayed by the earthquake. Moreover, a detail inspection found some damages such as small cracks in the concrete structure. Consequently, the restart of the JMTR will delay from June 2011 to this year. Now, the safety evaluation after the earthquake disaster is being carried out aiming at the restart of the JMTR. The renewed JMTR will be started from JFY 2012 and operated for a period of about 20 years until around JFY 2030. Expected utilization fields after reoperation will be a safety research of LWRs for materials/fuels, basic research for nuclear engineering such as HTGR fuels/materials, fusion reactor materials, industrial use such as production of Mo-99 for medical use, and education & training of nuclear scientists and engineers.