On September 15, the Canadian Nuclear Safety Commission (CNSC) conducted the second day of hearings into the renewal of Cameco Corporation’s licence to operate the McArthur River underground uranium mine and Key Lake uranium mill in northern Saskatchewan.
In both this session and the first day of hearings on July 7, Cameco came under fire from Commissioners and intervenors for its handling of the April 6, 2003 cave-in and flood of radioactive water at the McArthur River mine, the world’s largest uranium mine. The flood threatened to engulf the lower levels of the mine and a lot of expensive equipment; it ended up stopping production for three months while the company contained the flood and rebuilt the underground workings.
Cameco representatives admitted that consultants’ reports had warned of the possibility of a cave-in and major “inflow” and that they had inadequate pumping and water treatement capacity and no contingency plans. They also admitted that their internal geology and engineering used non-standard methodology and therefore couldn’t be analysed and compared to standard mine practice.
According to CNSC staff, workers’ radiation exposure was within guidelines, and no contaminated water was being released wthout treatment and testing. It turns out that this was more by good luck than good management. A series of reports by CBC reporter Dan Kerslake showed how Cameco had known about the danger of a cave-in for months if not years and how “miners worked without ventilation masks to save the mine and their jobs.”
According to Keewatin Visions, a miners’ group, CNSC staff were at the mine site within a few days of the event, but they did not go underground. They also reveal that miners installing bulkheads to contain the water flow were not informed that radon levels were 0.2 working levels (WL) between the bulkheads, but reached 28.9 WL downstream of the bulkheads and 129.6 WL upstream.
It was also revealed that the company had steel emergency doors had been previously fabricated but were left in storage at the comapny’s Key Lake site and never installed.
Standard mining practice is that a mine should have pumping capacity of five times its average inflow, according to Keewatin Visions. If this capacity had been in place there would have been no risk to the miners. Nevertheless, Cameco’s upgraded pumping capacity still falls short of this standard, with a capacity of barely twice the average inflow.
According to Keewatin Visions, dirty water was inadvertently pumped into the clean water line; as a result, miners experienced high radon exposures whenever they washed the floor in the refuge station or washed their hands.
Cameco’s excuse is that they had mined in the danger zone before, and they thought they could continue without taking precautions like installing extra pumping capacity or preventive measures like freezing the ore before drilling into it.
Given past experience, we expect the CNSC to approve the licence without any more stringent conditions.