Experience with sodium and its auxiliary systems

Fast Breeder Test Reactor is a 40 MWt, sodium cooled, loop type reactor, with two primary sodium and two secondary sodium loops. Sodium was charged into the secondary sodium and primary sodium circuits in 1985, after purifying the commercial sodium in the engineering hall and transporting to the reactor site. After purifying the sodium to the reactor grade in the online cold trap purification system, both primary and secondary sodium pumps were commissioned. For the first criticality, as the steam generators were not connected to the secondary circuit and reactor core was having only restrictive small carbide subassemblies, both primary and secondary sodium main pumps were operating far away from best efficiency points. Also, primary sodium pumps were hydrodynamically coupled in parallel. Steam generators were welded to the secondary loops later. The system as a whole performed very well in the last 20 years. This paper details the experience attained in the last 20 years on the sodium systems, incidents and unusual occurrences in the sodium and its auxiliary systems. (author)