Chennai, May 14 (IANS): Russia's integrated nuclear power player Rosatom on Friday said its machine building division has started stamping pipe blanks for main circulation pumps to be fitted in the Units 5 and 6 of the atomic power plants at Tamil Nadu's Kudankulam.

The Rosatom said the work was carried out in two stages - firstly the blanks by means of a press were given the necessary oval shape. At the second stage, the bending of items was performed.

After a two-stage holding in a furnace at a temperature of 870 to 1,080 degrees, the bend was placed in a specialised stamp. Under the pressure of the press with a force of 6,000 ton-forces, the blank was bent at 29 degrees.

After stamping, the items are subjected to machining. In total, eight bends of the main circulation pump for two units of the plant.

The main circulation pump is a first class safety item. It circulates the coolant at a nuclear power plant through the pipes of the main circulation pipeline from the reactor to the steam generator and vice versa.

The reactor is of VVER-1000 design, similar to the two 1,000 MW units (Units 1 and 2) that have started commercial power generation long back.

India's atomic power company, the Nuclear Power Corporation of India Ltd (NPCIL) is building four more plants - Units 3, 4, 5 and 6 - of 1,000 MW each at Kudankulam.