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Inoue, Shuichi; Yamaura, Takayuki; Ishikawa, Kazuyoshi; Saito, Takashi; Tsuchiya, Kunihiko
no journal, ,
no abstracts in English
Tsuchiya, Kunihiko; Longhurst, G.*; Chakin, V.*; Tazhibayeva, I.*; Druyts, F.*; Dorn, C. K.*; Kawamura, Hiroshi
no journal, ,
Beryllium has been utilized as a moderator and/or reflector in a number of material testing reactors. In fact, the nuclear properties of beryllium are its low atomic number, low atomic weight, low parasitic capture cross section for thermal neutrons, readiness to part with one of its own neutrons (n, 2n), and good neutron elastic scattering characteristics. Various problems of beryllium utilization are introduced for nuclear reactors and two points are proposed for the solution of irradiated beryllium wastes. Thus, it will be necessary to consider fundamental changes to the frame design, starting with the choice of beryllium material grade. Additionally, irradiation tests are planned for the design modification of beryllium materials. Beryllium material grades are selected for material modification and irradiation tests have been discussed. New measurement procedures in PIEs are also proposed for evaluation of lifetime extension. In this presentation, status and future plan of beryllium reflector development are introduced.
Nagao, Yoshiharu; Shiroya, Seiji*; Kawamura, Hiroshi
no journal, ,
The JMTR will restart on FY2011 after the refurbishment for new irradiation researches and utilizations. Higher operating availability is indispensable to satisfy increased irradiation demand after restart. The reactor operation must therefore increases from 180 days per year to 210 days per year. To achieve 210 days/year operation, preventive maintenance will be carried out systematically according to the maintenance plan after restart. In addition to shorten reactor maintenance time, it should be inevitable to shorten shutdown time caused by unexpected reactor scram. Considering how to achieve reactor operation of 210 days per year stably, the shortening of the shutdown time between reactor scram and restart is one of the most important items to be realized. The scram events in the JMTR and the system of safety regulation were therefore surveyed and investigated from the viewpoint of optimization of the research and test reactor management.
Nakamura, Takehiko; Nishiyama, Yutaka; Chimi, Yasuhiro; Hanawa, Satoshi; Ogiyanagi, Jin; Nakamura, Jinichi; Sasajima, Hideo; Suzuki, Masahide
no journal, ,
In parallel to the refurbishment, installation of new tests rigs for fuel and material irradiation research is progressing in the JMTR. The new test program will contribute to solve irradiation related issues on plant aging and high-duty uses of the current LWRs and on development of next-generation reactors. New tests on fuel integrity under simulated abnormal transients and high-duty irradiation conditions are planned in the JMTR. Power ramp tests of new- design fuel rods will also be performed in the first stage of the program, which is expected to start in year 2011 after refurbishment of the JMTR. For the materials irradiation, fracture toughness of reactor vessel steels and IASCC behavior of stainless steels are being studied in addition to basic irradiation behavior of nuclear materials such as hafnium. The irradiation studies would contribute not only to solve the current problems but also to identify possible seeds of troubles and to make proactive responses.