NATIONAL

Kaiga workers “back to work”

T.S. Subramanian

CHENNAI: About 55 workers of the Kaiga Atomic Power Station in Karnataka who received an excessive dose of tritium, a highly radioactive substance, after they drank water mixed with tritium are “normal” and “back to work,” according to officials of the Nuclear Power Corporation of India Limited (NPCIL). The officials blamed the incident on an “insider’s mischief” of mixing tritium in a water cooler kept in the operating island of the station’s first unit. “We have to investigate and fix responsibility for the mischief,” said an authoritative official.

The officials said their suspicion was confirmed when it was found that not only workers who worked in the radioactive areas of the first unit but also those who did not work in the radioactive zones had a high dose of tritium in their urine samples. This led to their zeroing in on the cooler where water had been mixed with tritium.

Kaiga has three operating Pressurised Heavy Water Reactors (PHWRs) of 220 MWe each. These PHWRs use natural uranium as fuel, and heavy water as both coolant and moderator. During the operation of reactors, a small quantity of deuterium in the heavy water gets converted into tritium, which is in liquid form. This tritium can be used in making hydrogen bombs.

An NPCIL release said that routine test on November 25 revealed tritium contamination in the urine samples of the workers.

A survey of the plant area did not reveal any leak of heavy water from any of the reactor systems. Besides, the radiological conditions of the area were normal. This meant that the tritium ingested by the workers was not from the plant, the release said. Further investigation revealed that the source of contamination was water kept in the cooler as it had been mixed with tritium. About 55 workers who drank the water were affected. They received medical treatment to reduce the dose ingested. “All are attending duties at the plant site,” it added.

The NPCIL officials denied allegations that workers had received burns. “None of them has been hospitalised,” they said.

An authoritative official claimed that “it was not lax security” that led to the incident. Workers carried radioactive samples in bottles from sampling points in the reactor building to chemical laboratories for analysis.