Spread over 3,50,000 square feet, the complex will make the largest nuclear steam turbine that can yield 1,700-1,800 MWe

It was a deceptively simple board — ‘Rotor machining, balancing facility.' But what surprised a team of journalists from India and France was the nearby big, long tunnel at the floor level. It had massive contraptions on which a big steam turbine rotor was positioned.

“This is the largest rotor balancing facility in the world,” said Aurelien Maurice, programme director of the facility. “We will close the tunnel, create a vacuum and start spinning the turbines. We can spin the turbines at 4,500 revolutions a minute. We can test rotors, 22 metres long and 8 metres in diameter, in this tunnel.”

We were at Alstom's manufacturing and engineering facility on the banks of the Tennessee River at Chattanooga, Tennessee, U.S., on its inauguration on June 24. It is the world's biggest facility that will turn out steam turbines for nuclear and coal-fired electricity generating stations, gas turbines, turbo generators, generator stator, gas turbine rotor and final assembly.

The factory will manufacture the world's largest nuclear steam turbine, “Arabelle,” that can yield 1,700-1,800 MWe. “Arabelle” is a versatile turbine that can go with any reactor. The facility will also retrofit steam turbines for both nuclear-powered and coal-fired stations.

The Chattanooga facility is the most transformed complex of Alstom, a global leader in making equipment for the power sector. Built at $300 million, the state-of-the-art factory, spread over 3,50,000 square feet, features the world's largest rotor balancing facility, the largest horizontal lathe in the industry and a barge dock on the Tennessee River, with a crane that can lift and swing around equipment weighing 1,000 tonnes.

No wonder, Alstom Power president Philippe Joubert called the factory “an alliance between beauty and power... Our new Chattanooga factory dramatically enhances Alstom's ability to build and retrofit power generation equipment for customers in North America and beyond.”

With a nuclear renaissance on the cards in the U.S. and President Barack Obama insisting that “the time to embrace a clean energy future is now,” Alstom foresees a big market for nuclear steam turbines in the coming years. In 2010, the installed nuclear power capacity from 104 operating reactors in the U.S. is 101.3 GWe, accounting for 19 per cent of the total electricity generated in the U.S.

After the Three Mile Island accident of 1979 and the subsequent logjam that the U.S. found itself in, it is now preparing to build 17 new nuclear power plants. Four units are partially built. The existing U.S. nuclear reactors are ageing, with 70 per cent of them more than 30 years old. Mexico, the U.S. neighbour, is keen on importing reactors. So Alstom sees a big market for its Chattanooga facility not only for manufacture of new steam turbines but also retrofitting of the old ones, be it in the nuclear-powered or coal-fired electricity stations. It has enough orders for the next two years from the U.S. for turbines.

There were four steps, Mr. Maurice explained, in the manufacture of a steam turbine: welding the different forgings; machining; installing the blades in the turbine; and balancing and testing the turbine rotor in the tunnel. “Our welding technology is one of our key technologies. Our rotors have a strong resistance to corrosion and have a long life. Rotor manufacturing is our priority,” he said.

The facility has 600 metres of underground tunnels to ferry machine tools.

At the on-site barge dock, where components can be received and finished turbines ferried to customers, there is a board which says, “Eighty per cent of North America's existing or planned nuclear power plants can be accessed from the Tennessee River.” Furthermore, Chattanooga has excellent road and rail links.