Development work on sodium pump for prototype fast breeder reactor 'Monju'

The circulating pump for the primary main cooling system of the fast breeder prototype reactor ''Monju'' is that for circulating radioactive sodium at 400 deg C in the wide range of flow rate from 8 to 113%, and is one of the most important machines and equipments regarding the operation and safety of the plant, as core-cooling function is always required for it. The research and development of this pump have been forwarded as the independent development with Japanese technology by the cooperation of the Power Reactor and Nuclear Fuel Development Corp. and Hitachi Ltd., and the perspective for manufacturing the actual machine has been cleared now through the operation experience of the experimental reactor ''Joyo'' and the endurance test with the mock-up machine for 10000 hours. In this paper, the outline and features of the primary main circulating pump, the result of development of the pumps for sodium, the characteristics of the mock-up pump in water and liquid sodium, the suitability of SUS 304 to this circulating pump, the prevention of natural convection of argon gas in the annular space, the measurement of shaft vibration, the trial manufacture and development of shaft displacement meter, and the disassembling and cleaning of the mock-up pump after the endurance test described. (Kako, I.)