A major radioactive leakage from ill-mantained pipelines in the vicinity of the CIRUS and Dhruva reactor complex at the BhabhaAtomic Research Centre, 15 km. from the heart of Bombay, is found to have caused severe soil contamination. Evidence also points to the possibility of the leakage having taken place for a number of years, thereby causing an outflow of contamination towards the sea.
The leakage was first detected by reactor workers on December 13, 1991, when a fountain of water shot out onto the lawn between the reactor and the sea. The plant management surmised that the sea-water pipeline must have burst, even though the entire area is criss-crossed with many other lines, carrying radioactive and chemical effluents. The establishment set six contract labourers on the task of digging a pit, to reach the burst pipeline, eight feet below the surface. These workers wore no protective gear or radiation monitoring badges.
The presence of radioactivity in the area may never have come to light had it not been for an alert official in the office of the Radiation Health Inspectorate at the complex, who got wind of the incident and sent for a water sample from the puddle in the excavated pit. The activity recorded in the water sample was 40 becquerel/ml.
The contract labourers who had worked for almost eight hours inside the pit on December 13 and 14, 1991, were thereafter hastily pulled out, given a bath, new sets of clothing and packed off home. There is no evidence of the labourers having been subject to radiation monitoring tests.
However, the authorities sought to deduce the dosage the labourers had received. On December 19, department personnel dug a small portion from the bottom of the excavated pit. During a 12-minute period, the whole body dose recorded by the DRD (a radiation monitoring badge) ranged from 10 to 30 millirems (mR). Extrapolating on this observation, the radiation exposure of the contract labourers is held to be in the range of 300 to 1,000 mR. (A normal chest X-ray gives a dose of 70 to 150 mR. This would amount to the labourer receiving 12 X-rays during the course of work.)
Tests done in the excavated pit showed a radiation dosage ranging from 200 to 700 mR/hour, while in one specific spot, described as the "Hot Spot area below the chamber" (inspection chamber along the pipeline), it zoomed to 2,000 mR/hour.
Recording of the "soil specific activity level" revealed the presence of Cs-137. In 50 percent of the samples, Cs-137 activity was 1-10 k Bq/gm, and in another 50 percent of samples it was 10- 60 k Bq/gm. Samples of vegetation in the area also revealed contamination, and birds and insects in this area are its carriers into a wider area.
Meanwhile, 325 drums of contaminated soil has already been sent to the Waste Management Department. The department has said that the solid active storage would get exhausted if the entire quantity of contaminated soil is to be excavated, and has stopped further consignments.
According to publications authored by BARC scientists, the "acceptable limit" for Cs-137 is 0.13 Bq/ml. in sea water. In the UK, the permissible limit of Cs-137 in soil is 900 Bq/kg (or 0.9 Bq/gm). Taking the average activity figures found in the CIRUS drums, around 27 k Bq/gm, it means that the activity is 30,000 times higher than permissible limits in the UK.
Circumstantial evidence at CIRUS points to discharge of Cs- 137 into the Arabian Sea, where despite the impact of dilution, the chances of it being imbibed by marine life are real.
What was the source of such widespread contamination? The radioactive wastes came from the Rod Cutting Building, where all uranium and plutonium fuel used in the reactor is stored for years in large pools of water, to allow decay and cooling of radioactivity before further treatment. To maintain purity, the storage pool is periodically washed with acid, and the effluents are dangerously radioactive. This discharge is piped to the waste treatment facility in a planned manner, and should never be allowed into the sea, atmosphere or land.
Yet, unbelievably, the pipeline carrying this deadly waste, also at other times, acted as a stormwater outlet. The system envisaged that by closing valves, the active discharge would be diverted to waste management, but in reality, for whatever reason, the untreated wastes flowed towards the sea.
The damage to the Concrete Inspection Chamber along the pipeline, where the highest activity is found, as also the sea water outfall pipe (made of half-inch thick steel and lined by two-inch thick RCC) which crosses the ceramic pipe, is evidence of the slow, corrosive force at work.
Worse still, the plant management was aware of leakage occurring in this same pipe, at the same spot, in 1978, but did nothing. At that time, during the construction of the Dhruva septic tank, several hundred metres away towards the sea, Cs-137 was found in the soil. The sample analysis read 20 Bq/ml. The source of leakage was traced to this same pipeline and inspection chamber. Apart from isolating the pipeline and inspection chamber for a while, no attempt was made to replace the decaying pipe-line. The report was filled and forgotten, sources alleged.