Contamination at Kaiga nuclear power unit likely "act of mischief": NPCIL

The Nuclear Power Corporation of India Limited (NPCIL) today said the radiation contamination of a water cooler at the Kaiga Atomic Power Station in Karnataka was possibly an "act of mischief" and did not involve any radioactivity releases or security breach.

NPCIL Chairman and Managing S K Jain said in a statement that the related agencies were investigating the matter.

As already reported in the media today, tritium contamination of some of the radiation workers was indicated by their routine bioassay last week, raising concerns about the safety of the plant. NPCIL did not give details about the number of workers affected, but media reports put it at 45.

NPCIL had said yesterday that a thorough survey of the plant areas did not indicate any heavy water leak from any of the reactor systems and the general radiological conditions were found to be normal in the plant areas, indicating that the tritium uptake was due to drinking of water from one of the water coolers, which was found to be contaminated. It said the cooler was isolated and put out of use.

According to Dr Jain, the contamination of the water cooler was a matter of concern and the cause was being investigated.

"Preliminary inquiry does not reveal any violation of operating procedures or radioactivity releases or security breach. It is possibly an act of mischief. The related agencies are investigating," he said.

The Kaiga plant has four units of Pressurized Heavy Water Reactors of 220 MWe each. The first three units have been commissioned and are operational, while the fourth is currently being constructed.

The Unit-1 is in biennial shutdown for routine maintenance works since October 20, while the Units 2 and 3 are operating normally.

"All the systems of all the units are healthy and there is no release of radioactivity to the environment within the plant site and outside," Dr Jain said.

He said that a number of measures for routine monitoring of radio uptake in workers were in place at the plant, one of which was routine urine sampling.

According to him, in this process, some samples indicated signs of contamination. After this observation on November 24, samples of all the radiation workers were analysed.

"All plant systems are working normally and cannot cause any contamination. The source of radiation contamination was identified to be a water cooler located outside the reactor building," he said.

Dr Jain said that any contamination caused by Heavy Water inside the human body was quickly flushed out through natural biological processes like urination and perspiration. These processes could be hastened through simple medication, he said.

"The contamination detected in this incident has been brought down quickly and currently one worker is close to the limit specified by Atomic Energy Regulatory Board (AERB)," he said. He pointed out that the AERB limit was one of the most stringent in the world.

"No worker is hospitalised. All workers are carrying out their duties. The radiation workers of the plant are highly experienced, access permits are routinely issued to all personnel entering the operating island and the computerised access control system has a record of all the personnel who have entered the operating island," the statement said.

Dr Jain said NPCIL had a very high level of safety compliance and the limits of regulatory authorities were strictly complied with. Prompt notification, as required by the procedures, was issued, he added.

NPCIL had said yesterday that the incident had not in any way affected public safety, health and the environment.

NNN