Chennai, Mar 8 (IANS): The Fast Breeder Test Reactor (FBTR), belonging to Indira Gandhi Centre for Atomic Research (IGCAR) in Kalpakkam near here, attained its design power level of 40 megawatt thermal (MWt) on Monday evening.

MWt refers to the input energy required for the power plant.

IGCAR Director B. Venkatraman said achieving design power level in FBTR is a landmark in its history.

Starting with a small core of 22 Mark-I fuel subassemblies rated for 10.5 MWt in 1985, the power was gradually raised in steps by adding fresh fuel subassemblies based on the performance of mixed carbide fuel in terms of fuel linear heat rating and burn-up.

However, with the limitation on reactivity in the core, the maximum power was limited to 32 MWt which was achieved in 2018.

For raising FBTR power to design power level, a novel core with few poison subassemblies was designed and safety analysis was carried out.

After getting the Atomic Energy Regulatory Board's (AERB) clearance, FBTR core was converted to a new 40 MWt core and all the reactor physics parameters were measured to ensure safety.

The reactor was re-started with a new core and power was raised to 40 MWt, Venkatraman said.

The FBTR went critical in 1985 and its power output will be about 13MW. The 1970s vintage FBTR is a sodium-cooled loop-type reactor, powered by plutonium-uranium carbide fuel.