Danger hunt: Villagers look for coal deposit from liquid ash near KTPS

It?s part of a student?s doctoral work at the Indian Institute of Technology (IIT) in Kharagpur ? an eight-page research paper published in a journal of the Indian Academy of Sciences. The paper, claiming that the Kolaghat Thermal Power Station (KTPS) near Calcutta that burns coal is releasing potentially hazardous radioactivity into the environment, has stired a debate, even a bit of anger, in scientific circles. Senior researchers are questioning the claim as well as the decision by the journal?s editors to grant space to it.

The controversy is centred over the flyash ? the grey powder-like residue of coal burning? churned out by the KTPS in Midnapur district. The flyash is disposed in ash ponds near the power station. Geophysicist Debashish Sengupta at IIT-Kharagpur has said the KTPS flyash has high levels of radioactivity, enough to warrant remedial measures in its disposal. He has also urged for curtailing the use of flyash bricks from KTPS to build houses until detailed studies are done.

In addition to carbon, coal contains a large number of trace elements that tend to concentrate in the residual flyash. Small amounts of uranium and thorium can make the flyash residues radioactive. In their study of radioactive elements in the flyash, Sengupta and his student Arpita Mandal discovered that thorium levels in the flyash from Kolaghat are about five times the average level in the crust. In a report published in the Current Science, the researchers say the average level of gamma radiation above the ash ponds is about 150 nanoGrey per hour. Grey is a unit of radioactive emmision.

The geophysicists have also cautioned that the uranium trapped in the ash ponds may be washed into the groundwater. Given the high dose of 150 nanoGrey per hour from the ash ponds, the disposal of the flyash may result in a ?radiation hazard? to the population living close to the ponds. ?Prolonged exposure to the high-dose rates may lead to the risk of lung or bone cancer,? Sengupta and Mandal said in their paper classified as a ?Research Communication? in the Current Science. Sengupta, who was earlier at the Physical Research Laboratory in Ahmedabad, has nearly 15 years? experience studying radioactivity in the environment. His study has also shown that flyash bricks from KTPS had higher levels of radioactivity than ordinary bricks. So those who live in houses made of flyash bricks will be continuously exposed to radioactivity emanating from the walls from all sides. The paper calls for reducing the use of flyash bricks until detailed probes are carried out to study the indoor radiation dose in buildings made with the flyash bricks.

The warnings have sparked an outcry from other scientists. ?This is nonsense, nothing but scaremongering,? says Vimal Kumar, head of the flyash utilisation division of the Technology Information Forecasting and Assessment Council (TIFAC) under the Department of Science and Technology. ?I fail to understand how Current Science published something like this.? He has reason to be angry. The TIFAC has spent the past decade urging India to make use of flyash, a waste product of thermal power stations. In recent years, the use of flyash bricks in constructing buildings has increased. In fact, the TIFAC?s own new building in New Delhi is built of flyash bricks. Kumar says that he has certificates from the Atomic Energy Regulatory Board approving the use of flyash bricks in buildings.

A top Bhaba Atomic Research Centre (BARC) scientist says radioactivity in flyash has been known for decades and studies were conducted during the 1990s to determine the exposure inside a room built out of flyash bricks. ?With adequate ventilation, there is no cause for worry about radiation,? the scientist says.

Scientists familiar with the IIT-Kharagpur study think that the radioactivity in the flyash may be higher than average, but it does not pose any health hazard. ?These fears are absolutely unwarranted,? says Dr Umesh Mishra, former head of the health safety division at the BARC, who has spent over three decades tracking radioactivity in the environment. Mishra concedes that the exposure level of 150 nanoGray per hour around the ash ponds may be up to ten times higher than the average which is about 10 to 12 nanoGray per hour.

Physicist often cite the case of villagers living around the thorium-laced high radiation beach sands of Kerala. ?The natural background radiation there is much higher than what the IIT Kharagpur team has found in the flyash. And we have not detected anything to suggest that the radiation along some parts of coastal Kerala is harmful to the population there,? says Mishra.

But Sengupta says it?s not just the dose of radioactivity, but the period of time that a person is exposed to it, that determines the health hazard. He?s now planning an analysis of flyash generated by the Bandel thermal power station.