The Lost Creek uranium mine north of Rawlins shut down operations Wednesday just weeks after reporting one of the largest spills of uranium injection fluid ever recorded in the U.S.
The spill was contained on site and is not a human health hazard, according to federal regulators. The spilled fluid had not yet been pumped into the uranium ore beneath the surface. Radioactive metal contained in the fluid was naturally occurring.
The mine, owned by Littleton, Colorado-based Ur-Energy, reported an Aug. 19 spill of 188,000 gallons of pre-injection fluid at Lost Creek. Another spill of 10,000 gallons of pre-injection fluid at Lost Creek on Tuesday was reported to federal regulators.
A call to the Ur’s Casper office was not returned Friday. It was unclear if the mine unit had returned to operation.
The larger spill covered about a half an acre, according the company’s notification to the Nuclear Regulatory Commission. The total amount spilled is roughly equivalent to a third the volume of an Olympic-sized swimming pool, which holds about 660,000 gallons of water.
The fluid that had collected in the basement of the header house, an onsite gathering location for the pipes, contained about 24 parts per million of U308, or uranium, wrote Michael Gaither, the company’s manager of regulatory affairs. Most of the spill was likely at a much lower concentration of 1.2 parts per million, the company stated in its report. The broken pipe was the result of “chronic stress,” Gaither wrote.
The second spill was in a separate header house, on the same mine site.
“Because the concentration of uranium is so low, it doesn’t pose any threat to public health and safety,” said Victor Dricks, spokesman for the Nuclear Regulatory Commission. “What the NRC will do is monitor the company’s response to both events, look at their corrective actions and document it in a future NRC inspection report.”
Wise-uranium.org, an online database that tracks all the NRC’s uranium notifications, says the spill may be greater because additional fluid was recovered from two locations at the mine.
In-situ uranium mining involves pumping an injection fluid of carbonated water into uranium rich formations to dissolve the potent metal. The solution is then pumped to a header house on the surface and then to a plant, where it is extracted and treated before processing.
Cameco’s Highland Mine had recorded the largest spill on record, with a nearly 200,000-gallon unplanned release of injection fluid in 2007, according to Wise-uranium. The NRC began tracking spill data on a public database in 1999.
Shannon Anderson, a lawyer for the environmental advocacy group, said she believed the company’s response to the spill was notable.
“Shutting something down would only happen if there are health and safety concerns with operating,” she said. “Shutting down is often the only way the industry can figure out what is happening. Spills, mechanical integrity failures, and other issues are pretty routine at these ISL sites, and the size of that spill at Lost Creek is significant.”