It is now generally recognized that rock with sub-economic levels of uranium mineralization has the potential to generate long-term environmental problems which require improved management techniques. The presence of nickel and arsenic in uranium ore deposits can exacerbate the problem.
In planning the development of the Collins Bay A-zone and D-zone ore bodies at Rabbit Lake, Cameco has employed some new methods for developing waste rock management plans, designed to prevent future problems rather than having to react to them after mining has been completed.
The regulatory requirement to model post-decommissioning radioactivity impact gave us the tools which could be used to model the long-term impacts for other non-radioactive elements. Probabilistic assessment of decommissioning alternatives was done by adapting a version of the Uranium Tailings Assessment Program (UTAP). These data, when coupled with experience gained in mining the larger but similar B-zone deposit, enabled us to develop a practical waste rock management plan, balancing costs to segregate waste rock on the basis of its anticipated long-term environmental performance against the future cost to manage an unsegregated waste rock pile. This approach will satisfy environmental concerns while allowing economic development to proceed.