Operation of the secondary cooling system of experimental FBR 'JOYO'

Development of Fast Breeder Reactors (FBR) is actively carried out in number of countries, for effective usage of uranium resources. Developed in Japan as a national project are experimental FBR ''JOYO'' and prototype FBR ''MONJU'', centered in Power Reactor and Nuclear Fuel Development Corporation (PNC). As the initial output of ''JOYO'', 50 MWt was adopted in application for its construction permission to the Government, granted in February 1970. The purpose of ''JOYO'' is to obtain experiences and solve technological problems through design, construction and operation of Japan's first sodium-cooled FBR. After completion, ''JOYO'' is used as an irradiation facility for development of fuels and structural materials. ''JOYO'' was completed in October 1974. Subsequently, function tests were from January 1975 to March 1977. It went critical on April 24, 1977. Described are the results of function tests on the secondary cooling system, including preheating test, initial purification test, performance test of pumps and vibration test of pipings. (auth.)