Investigators probing the radiation contamination of a drinking water cooler unit in Kaiga atomic plant in Karnataka have zeroed in on five employees from whose department the heavy water could have been smuggled out.
Sources privy to the investigations said on Tuesday that the contamination incident described as an "internal sabotage" had links to the department from where moderator heavy water is supplied for the nuclear reactor.
The laboratory examination of the water from the cooler showed only presence of tritium -- a radioactive isotope of Hydrogen -- and no other chemical.
Tritium is used in a type of heavy water which is used to moderate the high temperatures of the nuclear reactor while the coolant comprises tritium and other chemicals to cool temperatures in the reactor.
Sources said on November 23, things were normal but some radiation effects in some employees were noted only on the night of November 24.
The sampling of the moderate heavy water is done everyday whereas for coolant it is done once a week, the sources added.
Following this, a chart was prepared about the employees who had access to the moderate heavy water, out of which five people are being subjected to sustained questioning to unravel the mystery.
A team is probing the incident in which around 50 employees working in the first maintenance unit of the plant were tested for increasing level of Tritium, also known as Hydrogen-3, after they drank water from the cooler in the operating area on November 24.Kaiga Generation Station has four units of Pressurised Reactors each of 220 MW(e) at Kaiga. Unit 2 and 3 are operating normally. Unit 4 is under commissioning while Unit 1 is under annual maintenance shutdown since October 20 this year.