The published stories read as though heavy water or deuterium oxide used as a moderator and coolant in the Kaiga-1 nuclear reactor had somehow leaked and mixed with drinking water at the plant, leading to some 50 employees being hit by radiation sickness. To set the record straight, the number of employees that fell sick was right – but there was no "leak" or radioactive release at Kaiga.
Contrary to what the initial stories seemed to suggest, heavy water used in pressurized heavy water reactors like Kaiga-1 simply cannot “mix” with the drinking water supply at a nuclear power plant. There is no physical connectivity between the plumbing of the drinking water supply and the moderator tubes or coolant channels containing the heavy water.
What did happen, as confirmed by Indian authorities, was that a disgruntled employee poured tritiated heavy water into one of the water coolers outside the reactor building. All personnel who were found to be contaminated during routine urine tests had drunk water from this particular cooler.
As an independent journalist who has been taken on tours of some of India’s nuclear power stations, this writer can tell you that there are no coolers in the reactor building of a nuclear plant, nor for that matter are any eatables allowed there.
However, coolers are present in the service building, which is distinct from the reactor building and houses apparel-changing areas and restrooms. It was a cooler in the service building that was found to have been contaminated by someone who had poured tritiated water into the cooler through its overflow pipe, since the lid of the cooler itself was screwed shut.
The source of the radioactive heavy water was a tritium vial, which is normally used to carry heavy water samples from various parts of the reactor for routine chemical analysis. Some of these chemical analysis stations are located in the service building area. Tritium is a radioactive isotope of hydrogen, which is generated in heavy water during reactor operations. It is typically used in fusion research and also serves as an ingredient in boosted fission and thermonuclear devices.
India’s Atomic Energy Regulatory Board stated that all persons working in the plant were checked and anyone found to have ingested tritium was taken to hospital and given diuretics to accelerate the removal of the tritium by urination. After this treatment only two people showed levels of exposure to radiation that marginally exceeded safety levels. The two were to receive further medical treatment.
This is not the first incident of this sort. In 1990 the Point Lepreau Nuclear Generating Station in New Brunswick, Canada was witness to a similar perfidy. That time as well, a disgruntled employee had poured the contents of tritium sampling vials into a water cooler, leading to several employees falling ill.
The Indian nuclear industry is deeply regarded the world over for maintaining the most stringent safety standards. The World Association of Nuclear Operators has commended the Nuclear Power Corporation of India, which operates the Kaiga plant, on numerous occasions for its safety standards.
In fact, the early detection of tritium contamination shows the high priority accorded to personnel safety by India’s Department of Atomic Energy.
Every Indian nuclear plant has an embedded Health Physics Unit that operates independently of plant authorities and is directly controlled by the Department of Atomic Energy. These units are fundamentalist in their approach to worker safety and are tasked with issuing radiological permits, which contain the clearance as well as work duration, on any given day, for employees scheduled for operations in the reactor building.
There is no concept of “seating” in the reactor level, meaning there is no permanent station for any particular employee. Employees usually enter the reactor level on specific tasks for which clearance is separately granted on each occasion, and the time limit for such tasks is set by the health unit, taking into account ambient levels of radiation to which a worker will be exposed in a particular area of the reactor zone. In exiting the reactor level workers go through radiation scanners and can leave only when cleared by these machines.
Indian nuclear reactors are operated on an eight-hour shift basis, with four shifts of 60 to 70 personnel. One shift is used to facilitate the changeover. When the reactor is in operation, only authorized personnel of a particular shift are allowed into the reactor level, including those who are specifically tasked with collecting heavy water samples.
Contract workers hired for routine jobs like sanitation are typically allowed access only to the service building area and not in the reactor zone when the reactors are in operation. However, during maintenance shutdowns, contract workers may work in the reactor building but only under the supervision of permanent shift employees assigned to the reactor level. This was the case with Kaiga-1, which had been undergoing routine maintenance since October 20, when the recent incident occurred.
Heavy water sample collection is a specific, scheduled activity that cannot be carried out by just anyone. Conspiracy theorists that suggest tritiated heavy water can be found simply lying around a plant to be collected by anybody are indulging in flights of fantasy.
Access to all areas of the power plant, including the reactor building, service building and turbine room, can only be gained through computer-controlled grilles monitored by security personnel and requiring authorized electronic dog tags. All structures in the plant have surveillance cameras that record personnel movements.
Given all this, it is nearly impossible for an outsider to breach security at a nuclear plant. These controls also ensure that no terrorist can steal radioactive material from a nuclear power plant, as some alarmists like to fancy. So, in a sense, the public can breathe easy on that point.
However, as evidenced in the Kaiga incident, all these precautions are not enough to prevent a disgruntled insider from indulging in mischief that can seriously endanger colleagues. This needs to be looked into. While no system can be foolproof to every kind of internal sabotage, some new procedures might be needed to better guard against such acts.
This Article First appeared in UPI Asia.
