Misplaced trust

Print edition : January 01, 2010

The Kaiga Atomic Power Station, where 65 NPCIL employees were found to have received radiation doses in excess of prescribed limits in November.-

The Kaiga Atomic

ON April 17, 2004, three employees of the Waste Immobilisation Plant (WIP) of the Bhabha Atomic Research Centre (BARC) at Tarapur, Maharashtra, were exposed to radiation doses when they used, at different times, a particular chair in a room at the plant. Embedded in a fold of the cushioned seat of the chair was a vial of liquid waste containing caesium and strontium, both radioactive substances. The vial should have been sent to a counter for counting its radioactivity. Instead, it was found lodged in the chair. Top officials of the Department of Atomic Energy (DAE) laid the blame for the incident on mischief by a disgruntled WIP employee, who was dismissed.

Tarapur, about 130 km from Mumbai, then had two nuclear power reactors. (It has four now.) Liquid waste from these reactors is stored in underground tanks. Liquid waste is categorised as high-level and low-level. Solid waste is vitrified (converted into glass) and stored in capsules.

Five and a half years later, on November 24, 2009, at the Kaiga Atomic Power Station on the banks of the Kalinadi river in Karwar district of Karnataka, bioassay tests of the urine samples of 65 employees working in the first reactor building revealed that they had received radiation in excess of the prescribed limits. They were all employees of Nuclear Power Corporation of India Limited (NPCIL), which designs, builds and operates nuclear power reactors in the country. They had drunk water mixed with tritiated heavy water from a water cooler kept in the operating island of Unit-1. Tritiated heavy water is a radioactive fluid in the heavy water. The three operating reactors at Kaiga use natural uranium as fuel and heavy water as both coolant and moderator.

Two of the 65 employees received radiation doses above the annual limit of three rem (or 30 millisieverts) set by the Atomic Energy Regulatory Board (AERB), the watchdog organisation that monitors safety in nuclear installations in India.

A top DAE official blamed the incident on an insiders mischief. He said an insider had mixed tritiated heavy water in the drinking water kept in the cooler in the operating island of the reactor.

S.K. Jain, Chairman and Managing Director, NPCIL, also called the incident possibly an act of mischief. He explained that there was heavy water in the reactors moderator system and primary heat transporter. During the reactors operation, a part of the deuterium in the heavy water gets converted into tritium. (Deuterium and tritium are isotopes of hydrogen.) While light water contains two atoms of hydrogen and one atom of oxygen (H2O), heavy water contains two atoms of deuterium and one atom of oxygen (D2O). Tritium oxide, or super-heavy water, contains two atoms of tritium and one atom of oxygen (T2O). Trained, qualified workers took out vials of tritiated heavy water from the sampling points in the reactor building to the chemical laboratory (which, in this case, was situated outside the building) for analysis, Jain explained. This is done every day. When urine samples of 250 workers were tested on November 24, it came to light that 65 of them had received tritium radiation. Investigation revealed that water in the water cooler had been contaminated with tritiated heavy water. Preliminary inquiry does not reveal any violation of operating procedures or radioactivity release or security breach, he said.

Jain was confident that since the computerised access control system has a record of all the personnel who have entered the operating island, it was only a matter of time before the mischief-maker would be identified.

The DAE/NPCIL do not seem to have become wiser after the incident at the WIP at Tarapur. No closed-circuit cameras have been installed in the corridors/passages leading from the sampling points in the reactor buildings to the chemical laboratories, which are generally situated outside the reactor building.

With touching naivete and implicit faith in their staff, top NPCIL officials explained away the absence of closed-circuit cameras. Their unanimous argument was: The workers are our staff. Their antecedents were checked before they were appointed. So there is no need to monitor every movement of a worker. Besides, they argued, it was not feasible to install cameras all over the nuclear power plant from end to end, and that cameras had been installed in what they called strategic areas, sensitive spots or vital points.

But all of them declined to reveal what were the strategic areas or sensitive spots where closed-circuit cameras had been installed. An AERB official frankly admitted: The closed-circuit cameras have been installed at strategic locations so that nothing is removed without authorisation. But who would have thought a fellow would go out of his mind and mix tritiated heavy water with drinking water? One NPCIL official said that the vial containing tritiated heavy water would not be detected by radiation-monitoring counters if it was covered with a piece of cloth.

A top DAE official said, There are a large number of places where closed-circuit cameras have been installed. There were no cameras here because it was a corridor [in Unit-1 at Kaiga]. The cameras were not installed then because the decision at that time was based on a [particular] scenario. Now you have to factor in this scenario [of an employee spiriting away the vial containing tritium and mixing it with drinking water in the cooler].

The AERB sent two of its officers to Kaiga. They concluded that a drinking water cooler was the source of the tritium contamination. The water tank of this cooler, like other water coolers, was kept locked. However, said Om Pal Singh, AERB Secretary, in a press release, it appears that a mischief maker added a small quantity of tritiated heavy water to the cooler, possibly from a heavy water sampling vial, through its [coolers] overflow tube.

Officials of NPCIL and the AERB also played down the gravity of the ingestion of tritiated heavy water by the 65 employees. An update on the incident from Jain on November 29 said: Any contamination caused by heavy water inside the human body is quickly flushed out through natural biological processes like urination and perspiration. These processes can be hastened through simple medication. The contamination detected in this incident has been brought down quickly and one worker is currently close to the limit specified by the Atomic Energy Regulatory Board. No worker is hospitalised.

Om Pal Singh argued that the administration of diuretics accelerates the process of removal of tritium from the human body by urination and said the personnel who ingested the tritiated heavy water were referred to hospitals for the administration of diuretics.

But according to an article in Science and Democratic Action, published by the Institute for Energy and Environmental Research, United States, in its August 2009 issue: As radioactive water, tritium can cross the placenta, posing some risk of birth defects and early pregnancy failures. Ingestion of tritiated water also increases cancer risk. These observations form part of the lead article, Radioactive Rivers and Rain: Routine Releases of Tritiated Water from Nuclear Power Plants, by Annie Makhijani and Arjun Makhijani. They observed: The problem of routine tritium emissions is, in our opinion, underappreciated, especially because non-cancer foetal risks are not yet part of the regulatory framework for radionuclide contamination and because tritium releases constitute the largest routine releases from nuclear power plants.

Although the Kaiga incident came to light on November 24, it was not before November 30 that the Kaiga station officials formally requested the Mallapur police for an investigation. Notwithstanding the NPCIL top brass confidence in the computerised access control systems, biometrics and the list of 250 employees who work in Unit-1, neither the State police nor the Central intelligence agencies had zeroed in on the mischief-maker as of December 7.

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