The stagnant coolant water in the reactor vessel and pipes in the first unit of the Koodankulam Nuclear Power Project (KNPP) is giving sleepless nights to scientists and engineers who say the risk of damage to the equipment is increasing each day.

"Water has to be circulating so that the components are not exposed to the risk of corrosion. However, the quality of stagnant water will deteriorate over a period of time, which in turn poses a risk to the reactor components like the primary pipes and the reactor vessel," said a KNPP official preferring anonymity.

Project work since last month has come to a standstill with intensifying protests by villagers on grounds of safety. Roads have been blocked and the local administration has advised the KNPP staff to sit tight inside their homes, fearing violence.

India's nuclear power plant operator Nuclear Power Corporation of India Ltd (NPCIL) is building two 1,000 MW nuclear power reactors with Russian technology and equipment in Kudankulam, around 650 km from here. The first unit is expected to go on stream in December. The project is estimated to cost around Rs.13,160 crore.

Citing the completion of the ‘hot run’, a trial run of the reactor with dummy fuel, NPCIL officials say the coolant water should be continuously circulated.

"It is the demineralised water - water in pure form - which is fed into the systems. However, to maintain its purity the water should be circulated as stagnant water will interact with the metal surface and quality will change," K.S. Parthasarathy, former chairman of Atomic Energy Regulatory Board (AERB), told the media.

Parthasarathy said there would be a water chemistry group to look at the quality of water used in reactors.

"Water is a hostile fluid. It is not desirable to have stagnant water inside a reactor. However, it is not a serious issue as the number of days that the water remains stagnant is comparatively low," Parthasarathy added.

"Maintaining the purity of stagnant water is an issue that is facing us. We are not able to check the chemistry of the water that is inside the power plant," an NPCIL official told the media.

The helpless officials confined to their homes for nearly a month are hoping that there is no major damage to the reactor components resulting in further delays to the project.

"The reactor vessel is a huge component and cannot be bought off the shelf or fabricated at a short notice. I hope nothing happens to the vessel," a worried senior NPCIL official told the media.

"The systems cannot be stopped and restarted. Decommissioning a reactor is different as one need not bother about the damages the systems would undergo after the plant is stopped," said the official, who spoke demanding anonymity.

On September 22, the Tamil Nadu government passed a resolution urging Prime Minister Manmohan Singh and the central government to halt work at Koodankulam till the people's fears are allayed.

M. Pushparayan, convenor of the Coastal People's Federation and member of the state committee representing the People's Movement Against Nuclear Energy (PMANE), told the media: "The plant should not be restarted at any cost. We want the plant to be shut down."