Operation and utilization of JRR-2

Japan Research Reactor No.2 (JRR-2) was a heavy water moderated and cooled reactor which burned 93% enriched uranium fuel placed in cylindrical and MTR type plates. Since attaining its initial criticality in October 1960, the JRR-2 has been used with the maximum thermal neutron flux of 2 x 1014 n/cm2·sec at the power level of 10 MW for various experiments, such as neutron physics, solid state physics, material irradiation, reactor fuel irradiation and radioisotope production. The reactor has been satisfactorily operated and utilized for more than 27 years since the initial criticality of October 1960. Since the first start up at normal power in October 1962, the JRR-2 completed approximately 62,000 hours of operation. The core has been converted from HEU (93% EU) fuel to MEU (45% EU) fuel since November 1987, in order to increase proliferation of nuclear resistance of the JRR-2 fuel. In this paper. a general description is given on the JRR-2. (author)