CHENNAI: Multiple layers of safety are being built into the two Russian reactors under construction at Koodankulam in Tirunelveli district in Tamil Nadu, and the reactors can withstand natural disasters such as tsunami, earthquakes and cyclones, according to S.K. Agrawal, Director (Projects), Nuclear Power Corporation of India Limited (NPCIL). The NPCIL is building the two reactors, each with a capacity of 1,000 MWe, on the Koodankulam coast.

A public hearing is to be held at the township at Chettikulam near Koodankulam on January 31 on the construction of four more Russians reactors (three to six) of 1,000 MWe each at Koodankulam for which a memorandum of intent was signed on January 25 by India and Russia during Russian President Vladimir Putin's visit.

When the tsunami devastated the nearby Kanyakumari coast, killing scores of people in December 2004, no water entered either the nuclear power project site or the township situated some km away because of their grade-level, Mr. Agrawal said. (Raised ground level is called grade-level).

Cyclones and earthquakes had been factored into the design of the reactor buildings, that can withstand air-crashes and shockwaves from explosions.

The fuel — enriched uranium — is encased in tubes, which are housed in the reactor pressure vessel made of a 22 cm-thick stainless steel wall. The vessel, which weighs 330 tonnes, is filled with water, which acts as a shield.

The vessel itself is kept inside a concrete vault whose wall is one metre thick. The vault is surrounded by a double containment dome.

The dome has a 1.2 metre-thick wall, its inside covered by a steel lining of six mm thickness. The weld joints in the lining are tested for leak-tightness. Then comes the secondary containment of 60 cm thickness.

Mr. Agrawal said: "This is the kind of multi-layered safety we are building into the reactors. Even in a hypothetical situation, if there is an uncontrolled rise of temperature which can melt the fuel, there is a core-catcher which is provided below the reactor pressure vessel to hold the molten fuel so that no radiation goes out into the atmosphere."

In an emergency, the reactor stopped automatically without any human intervention.

The NPCIL had given "a categorical assurance" that no water from the Pechipparai reservoir in Kanyakumari district would be used for the power plant, he said.

Desalination plant

A desalination plant, which would serve the needs of the reactors and the township, was working.

No irradiated water would be let into the sea from the reactor.

"We draw the sea water from the same place [where the coolant water is let into sea], desalinate it and use it as drinking water in the township. Will we compel any family to drink irradiated water?" Mr. Agrawal asked.

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