Cigar lake: A natural example of long-term isolation of uranium

Much research is being conducted to determine the best and safest way to permanently dispose of radioactive wastes. Particularly challenging is waste from the nuclear fuel cycle because of its content of long-lived radionuclides. Long-term predictions on the safe performance of any disposal concept for high-level waste cannot draw on experience with existing manufactured systems on similar timescales. However, there are ways to build confidence in such long-term predictions by looking at evidence from analygous systems and processes in nature. One of these natural analogs for a multibarrier disposal system is the 1.3 billion year old Cigar Lake uranium deposit in northern Saskatchewan, Canada. The Cigar Lake deposit contains a high-grade uranium ore embedded in a thick, clay-rich zone, situated about 430 meters below the surface. This deposit has been well preserved for a long time, but has no known signatures at the surface. This article describes this natural system and how the information can be applied to long term disposal of high-level radioactive wastes