Twenty five years of operating experience with the Fast Breeder Test Reactor.

Abstract: Sodium cooled fast breeder reactors constitute the second stage of India''s three -stage nuclear energy programme, for effective utilization of the country''s limited reserves of natural uranium and exploitation of its large reserves of thorium. The Fast Breeder Test Reactor (FBTR) at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, is a loop type, sodium cooled fast reactor. Its main aim is to provide experience in fast reactor operation, large scale sodium handling and to serve as a test bed for irradiation of fast reactor fuels & materials. FBTR was built on the lines of the French Rapsodie-Fortissimo reactor, with modifications to make it a generating plant. FBTR went critical on 18th Oct 1985 with a small core of 22 fuel subassemblies of a unique, high Pu carbide fuel. The core was rated for 10.5 MWt. The TG was rolled and synchronized to the grid in July 1997. Reactor power was progressively increased by enlarging the core, to reach 18.6 MWt. Several challenges in reactor operation came on the way, which were successfully overcome. A large number of modifications were carried out to improve the plant performance. The reactor coolant used (Sodium) is highly reactive when exposed to atmosphere and also becomes highly active on exposure to neutron radiation. These properties of sodium make it essential to handle it carefully and safely within a leak tight containment. During course of operation of the reactor, a number of sodium laden components viz. pumps, valves, cold traps, Rupture discs, level probes, shielding plugs, control rod drive mechanisms, experimental assemblies, piping etc. are required to be removed for various maintenance, modification and replacement jobs. This paper details the experience with operation and maintenance of India''s only one fast reactor power station. [Copyright &y& Elsevier]