Cameco has restarted pumping water out of the Cigar Lake uranium mine, which was flooded after a rock fall in October 2006. The firm expects it to take six to 12 months to dewater and secure the mine.
Following the flooding three years ago, Cameco decided to close two bulkhead doors to contain the water inflow within the future mining area, protecting shaft No. 1 and the processing area. But one of the doors did not seal properly which allowed significant water to flow into the processing area. Efforts to seal the door were not successful, and it was not possible to pump out the water quickly enough so the underground working areas of the mine were flooded.
In early 2007 Cameco launched a plan to remediate the mine. The dewatering of shaft No. 1 was progressing well until August 2008 when it had to be temporarily suspended after a significant inflow of water.
Cameco has now announced that the inflow on the 420m level that forced suspension of dewatering has been remediated by remotely placing an inflatable seal between the shaft and the source of the inflow and subsequently backfilling and sealing the entire development behind the seal with concrete and grout. The 420 level is not part of future mine plans.
It is currently expected to take six to 12 months to dewater and secure the mine depending on what conditions are found in the shaft and the underground workings.
Cameco has approval from the Canadian Nuclear Safety Commission to dewater and secure the underground development. It has applied to the CNSC for a licence amendment to allow completion of remediation and mine construction. A hearing is scheduled for November..
Cameco says it will provide an estimated production start date after the water has been pumped out of the mine, the condition of the underground development has been assessed, and the findings incorporated in the new mine development and production plans.
Cigar Lake is owned by a consortium of Cameco (50%) of Areva Resources Canada (37%), Idemitsu Canada Resources (8%) and Tepco Resources (5%)