Bhubaneswar, Jan. 10: Seventeen persons fell ill when chlorine gas leaked from the NTPC-owned Talcher Thermal Power Station (TTPS), authorities said here today.

The leakage occurred in the water treatment plant of the 460MW plant, which was taken over by NTPC in 1995, around 5pm yesterday, when the chlorine containers were being changed. Chlorine is used for the treatment of water, which the plant requires aplenty.

The director of factories and boilers, Himanshu Shekhar Mohanty, said the matter was under investigation and he had asked officials of the plant, located at Talcher, around 140km from Bhubaneswar, to take up the issue with the Jharkhand-based company that supplies chlorine.

Mohanty said three TTPS executives and four Central Industrial Security Force (CISF) personnel were among those affected by the gas leak. However, he said the sickness was “not serious in nature”.

Sources said that those who inhaled the gas developed difficulty in breathing and some of them fell unconscious. They were rushed to the TTPS hospital, situated 1km away from the plant.

“All the 17 persons were admitted to the hospital last evening with various complaints after they inhaled chlorine gas, but they were treated successfully here. All but three of them were discharged last night. The three were discharged this morning,” said TTPS chief medical officer H.R. Deb.

The mishap occurred when the workers tried to replace an exhausted chlorine container with a new one in the water treatment plant. “It seems some of the gas leaked during the process but it was not much. Chlorine inhalation can cause nausea and vomiting. But it is a heavy gas and so it cannot fly up,” said Mohanty, explaining that there was no cause for concern.

Sources in the plant said that apart from the workers and executives engaged in changing the chlorine cylinders, the rescue team members consisting of CISF personnel also fell sick after inhaling the gas. There was panic all around when the news spread.

Deputy director of factories and boilers Hrudaya Sahu, who rushed to the spot, said: “We will investigate the matter and action will be initiated against the erring officials.”

This was not the first case of people falling ill in the state after inhaling chlorine.

On June 21, 2010, at least 35 people fell ill when chlorine leaked from a cylinder of the urban water supply department in Berhampur. Those affected included schoolchildren, women and employees of the department.

In another incident on November 27, 2011, in Bhubaneswar, 17 people were fell ill after getting exposed to chlorine gas leaked during a water purification exercise in the Niladri Vihar area.

Additional reporting by BK Rout