India’s first indigenously designed 500MW fast breeder nuclear power project at Kalpakkam achieved its second milestone when the huge main vessel was lowered into the safety vessel, an official said on Sunday.

“We have been waiting to do this for quite sometime but were not permitted by the rain gods. As the sky was clear, we decided to go ahead with the lowering of the main vessel and completed it on Saturday,” Project Director Prabhat Kumar told IANS from Kalpakkam in Tamil Nadu.

The Rs. 5,600 crore project is being built by the Bharatiya Nabhikiya Vidyut Nigam Limited (Bhavini) at the Kalpakkam nuclear enclave, around 80 km from here.

A fast breeder reactor is one which breeds more material for a nuclear fission reaction than it consumes and key to India’s three stage nuclear power programme.

Lowering of the huge stainless steel main vessel - 12.9 metres in diameter and 12.94 metres in height, weighing 206 tonnes - is considered a major step in completing the 500 MW power project by the September 2011 deadline.

The lowering of main vessel was delayed as civil construction works are on and the officials did not want to risk even a speck of dust inside the vessel that would hold the coolant liquid sodium, reactor fuel and grid plates.

The sodium-cooled fast reactor designed by the Indira Gandhi Centre for Atomic Research (IGCAR) has three vessels - a safety vessel, a main vessel and an inner vessel.

Outermost is the stainless steel safety vessel, which was lowered into the reactor vault last June - the first milestone.

The third and smallest of the three vessels is the inner vessel - 11 metres tall. It houses pumps, heat exchangers and other equipment. Together, they all go inside the main vessel.

The cone-shaped inner vessel, thermal baffle, grid plate and primary pipes are also ready and officials expect the roof slab of the nuclear reactor to be closed by next March.

As for the power generation part of the project, erection of the gas-insulated switchyard is nearing completion and the gas filling process has begun.

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