By Venkatachari Jagannathan
Chennai, Oct 28 (IANS) Armed with the Atomic Energy Regulatory Board’s (AERB) clearance for erection of major nuclear reactor components, officials of Bharatiya Nabhikiya Vidyut Nigam (Bhavini) building the Rs.5,600 crore fast reactor near here are gearing up for constructing the huge main vessel.

India’s first indigenously designed breeder reactor — which breeds more material for a nuclear fission reaction than it consumes — is being built by Bhavini at the Kalpakkam nuclear enclave, 80 km from here.

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.

“We are in the process of creating 100 percent clean environment around the reactor vault so that the main vessel can be lowered inside the already erected safety vessel. The nuclear vault chamber has been air-conditioned,” project director Prabhat Kumar told IANS.

As civil works are on in the building housing the reactor vault, officials do not want to risk even a speck of dust inside the main vessel that would hold the coolant liquid sodium, reactor fuel, grid plates and others.

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.

Activities connected with the erection of the main vessel — drawing up the scheme for lifting the vessel, other mock up activities, load testing — have commenced at the project site despite the threat of rain. The officials have kept a two-day window for the operation which should not take over three hours.

Speaking about the status of other critical components, Kumar said the 11-metre-tall cone-shaped inner vessel, thermal baffle, grid plate and primary pipe were ready. The reactor control rods were being tested.

“By March next year the roof slab of the nuclear reactor vault will be erected,” Kumar said.

The other major project activities completed are the erection of four 12.5-metre-tall argon buffer tanks and the transfer of around 825 tonnes of sodium to the sodium storage tanks.

“The construction of the 365-metre sea water intake channel built undersea is over. Similarly, construction of jetty and 1.8 km outfall structure are over. We are expecting to get the primary and secondary sodium pumps and two steam generators from the vendors by the end of this fiscal,” Kumar added.

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.