Feb 2, 2009

India - Kudankulam first reactor work nearing completion

T.S. Subramanian

The containment dome of the second reactor building, seen through the barrel-hole of the first reactor building of the Kudankulam Nuclear Power Project in Tamil Nadu.

CHENNAI: The view through the barrel-hole, situated at a height of 31 metres, is stunning. It frames the massive containment dome of the reactor building of the second unit of the Kudankulam Nuclear Power Project (KKNPP) in Tamil Nadu.

Tower cranes are swinging around the dome at a great height and the ground below is buzzing with activity. A little away is the fuel storage building, painted in light yellow, where the ready-to-load enriched uranium fuel assemblies for the first reactor have been stacked up.

Of the two Russian reactors under construction at Kudankulam, the first unit is fast nearing completion. It will be commissioned by the middle of 2009. Each unit will generate 1,000 MWe. Although the reactors are imported from Russia, the Nuclear Power Corporation of India Limited is building them.

A misnomer

The name barrel-hole is a misnomer. It is a massive circular opening, 9.9 metres wide, at a height of 31 metres in the reactor building. Erecting the reactor equipment inside was no easy job.

A powerful crane winched up very heavy equipment such as the reactor pressure vessel, which weighed 320 tonnes, four steam generators of 306 tonnes each and a 180-tonne pressuriser. Then they were moved into the reactor building through the barrel-hole and wheeled inside on a specially designed railtrack. When the entire reactor is ready, a 22-tonne door, called air-lock, will seal the barrel-hole. The reactor building itself is 80 metres tall.

K.C. Purohit, Project Director, KKNPP, said: “About 98 per cent of the civil construction has been completed for the first unit. On the mechanical side, we have completed 95 per cent of the equipment erection. On the piping side, which is an important front, we have the primary and secondary circuits, and on the turbine side too, a majority of the piping has been installed … The good news is that our Indian engineers have absorbed the [Russian] technology and executed the erection work in the most efficient manner.”

A.K. Pal, Chief Construction Engineer, gave a glimpse of the complexity of the operation involved: “The reactor pressure vessel, weighing 320 tonnes, has to be lowered inside without a scratch. We have to maintain its mirror-finish.” All the equipment had to be erected in a specialised manner in a confined space.

“Most difficult work”

K.S. Rao, Project Director, Kudankulam 3 and 4, called the installation of such equipment “the most difficult assignment I and Pal have done since 1970.” It demanded devising of methods and procedures, and building of tackles, assemblies and testing facilities.

“You can imagine the complexity of tooling,” said Mr. Purohit, “when you handle equipment, each weighing 300 tonnes. This is a typical operation in which mechanical erection and civil construction have to go in tandem.” According to M.I. Joy, Additional Chief Engineer (Site Planning), most of the turbine equipment were in place too. ith the entire enriched uranium fuel required for the first two years of operation of the first unit having arrived at Kudankulam, the next significant milestone will be the loading of the fuel into the first unit in the second quarter of 2009 and thereafter its commissioning.

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