Status of HTGR development program in Japan

Considering global warming due to emission of greenhouse gases it is essentially important to make efforts to obtain a more reliable and stable energy supply by extending use of nuclear energy which includes high temperature heat generated by nuclear power plants. Hence, efforts should be made continuously to establish and upgrade technologies of High Temperature Gas-cooled Reactor (HTGR), which can supply high temperature heat with high thermal efficiency and high heat-utilizing rate. It is also expected that making basic research at high temperature using HTGR will contribute to innovative basic research in the future. The construction of the High Temperature engineering Test Reactor (HTTR), which is an HTGR with the maximum helium gas coolant temperature of 9500C at the reactor outlet, was decided by the Atomic Energy Commission of Japan (JAEC) in 1987 and successfully completed by the Japan Atomic Energy Research Institute (JAERI). Functional tests of the HTTR have been carried out since May 1996. First criticality will be attained in the near future. The project is intended to establish and upgrade the technology basis necessary for HTGR developments. Heat utilization system is planned to be connected to the HTTR and demonstrated at the initial stage of the second core. Steam reforming of methane for hydrogen production is adopted as an HTTR heat utilization system. The JAERI also plans to conduct material and fuel irradiation tests as innovative basic research as well as safety demonstration tests after attaining coolant gas temperature of 950C. Preliminary tests on selected research subjects such as new semiconductors, superconductors and composite material development, have been carried out at high temperature and under irradiation. This paper describes major features of the HTTR, present status of its construction and prospects on test programs using the HTTR, and the other activity on HTGRs in Japan. 2 refs