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Three-tier system guards Kalpakkam

Three-tier system guards Kalpakkam
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First Published: Fri, Mar 18 2011. 12 27 AM IST
Updated: Fri, Mar 18 2011. 12 27 AM IST
Kalpakkam, Chennai: A three-tier system of sandbags, rocks and embankment put in place after the 2004 tsunami that lashed this southern Indian coastal town can nullify the impact of sea waves as large as the ones that disrupted nuclear power stations at Fukushima, Japan, last week and stoked fears of a radiation leak, scientists say.
Though the 220 megawatt (MW) reactors at the Indira Gandhi Centre for Atomic Research (IGCAR) are just two of India’s 20 commissioned nuclear power plants, they are the only ones in the direct line of a tsunami.
Most geologists say tsunami waves that can threaten India can only be generated by massive earthquakes at the volatile fault line that separates two tectonic plates, called the India and Burma plates, that are close to the Andaman islands.
“Rest assured, there’s nothing to be worried about,” said Prabhat Kumar, senior director at IGCAR. Kumar is in charge of constructing so-called fast breeder reactors, the next generation of reactors, which can produce about 500MW each. He is closely involved with the maintenance of existing reactors, which produce nearly one-tenth of India’s nuclear power.
The 11 March earthquake and tsunami in Japan killed thousands of people and caused explosions at three nuclear reactors. The catastrophe, which follows nuclear disasters at Three Mile Island, US, in 1979, and Chernobyl, Ukraine, in 1986, has triggered fears about the safety of India’s nuclear plants.
By 2020, India expects to generate at least 20 gigawatt of power from nuclear sources, an almost fourfold increase from current levels, by building more powerful reactors with the help of domestic and global private companies.
Kalpakkam, according to India’s seismic zoning maps, is in zone 2, or prone—at worst— to quakes of magnitude 5 on the Richter scale. In comparison, the 10 metre (m) high waves that lashed Japan were caused by a quake of magnitude 9.1 on the Richter scale just 130 kilometres off its coast.
Scientists at the Kalpakkam station, which is located 9.7m above the ocean’s surface, said attributes such as wave surge and impact were as important as the height of the waves to judge their destructive potential.
According to the region’s seismic zoning, the station is designed to withstand waves that are 5.2m high. In conjunction with the three-tier system that buffers the plant’s boundaries from the coast by nearly 500m, it is strong enough to withstand even 9m-high onslaughts.
V. Manoharan, an engineer at the plant who survived the 2004 Indian Ocean tsunami by clinging on to rafters at the church he was attending on 26 December, said waves of the height of Japan’s tsunami would send some water into the plant, but it would “gently recede away, like waves at the beach”.
The 2004 tsunami, which sent 6-7m high waves that swept the residential section of the research centre to the Tamil Nadu coast, killed five employees, who were among a total of 30 casualties reported from Kalpakkam. The tides forced one of the reactors at the Kalpakkam plant into “a safe shutdown mode”—which meant the plant was manually shut down as a precaution, though, according to officials, operations were back to normal within three days.
Apart from this first line of defence, officials at IGCAR said the power stations were connected to a series of diesel- and battery-powered backups that could power the station at full load continuously for seven days and were designed to immediately begin cooling down the reactors.
On Tuesday, India’s apex atomic energy regulator, the Atomic Energy Regulatory Board (AERB) said it will carry out a comprehensive reassessment of safety and emergency mitigation measures at all the Indian nuclear power plants in the light of the Japanese crisis.
Emergency-preparedness plans exist for all nuclear power plants in India, and they are periodically rehearsed, AERB said in a statement. “It is constantly monitoring the situation at Japan’s nuclear sites in the aftermath of unprecedented earthquake and tsunami,” it added.
In India, out of 20 reactors— 19 of which are in operation— only two units at Tarapur, Maharashtra, are boiling-water reactors similar to the ones at Fukushima.
All the reactors in India are designed to withstand the effects of earthquake and tsunami of specific magnitudes, which were decided based on conservative criteria.
“India has to have a variety of power sources at its command,” said Baldev Raj, director at IGCAR, “As far as we’re concerned, whatever known risks—cyclones, fires, tsunamis, earthquakes—have been accounted for in our designs. We’ll have to wait for more details from Japan to see what more can be incorporated in our designs to make them safer.”
jacob.k@livemint.com
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First Published: Fri, Mar 18 2011. 12 27 AM IST