Through the years, the U.S. Nuclear Regulatory Commission (NRC) has licensed numerous uranium recovery facilities in the United States, which used a variety of extraction methods to glean uranium from ore. The following table compares the features of the three main types of facilities, which include conventional uranium mills, heap leach/ion-exchange facilities, and in situ recovery facilities.
| Feature | Conventional Uranium Mill |
Heap Leach Facility | In Situ Recovery Facility |
|---|---|---|---|
| Recovery Method | Physical and chemical process to extract uranium from mined ore. | Physical and chemical process to extract uranium from mined ore that has been piled in a heap. | Chemical process to extract uranium from underground deposits. |
| Siting/Location | Generally located in the vicinity of the ore body. Mined ore can be trucked from the mine to the mill. The mine can be either a deep underground shaft or a shallow open pit. The NRC does not regulate the mining of ore. | Generally located in the vicinity of the ore body. Mined ore can be trucked from the mine to the mill. The mine can be either a deep underground shaft or a shallow open pit. The NRC does not regulate the mining of ore. | The wellfield area is located within the ore body. The processing plant is typically in the vicinity of the ore body. |
| Surface Features | Mill building(s), process tanks, tailings impoundment, and evaporation ponds | Process buildings, heap pile consisting of ore crushed to a size of approximately 1-inch in diameter, with an engineered liner system beneath the heap pile and liquid application on top of the pile | Wellfield(s) consisting of groundwater injection and extraction wells, header house(s), pipes, processing facility, storage or evaporation pond(s), and deep injection wells for liquid waste |
| Approximate Size | Impoundments are limited to 40 acres in size; however, a facility can have multiple impoundments and typically total on the order of hundreds of acres | Heap piles are limited to 40 acres in size; however, a facility can have multiple piles and typically total on the order of hundreds of acres | Thousands of acres |
| Wastes Generated | Mill tailings, a sandy material left over from the crushing process, disposed of within an impoundment; pipes, pumps, and other process equipment that cannot be decontaminated | Heap pile remains in place after processing; pipes, pumps, and other process equipment that cannot be decontaminated | Liquid waste, which is disposed of in a deep disposal well or through an evaporation system; pipes, pumps, and other process equipment that cannot be decontaminated are sent to an NRC-licensed facility for permanent disposal |
| Decommissioning | Demolition of mill and site buildings, final cover system installed over tailings pile, groundwater monitoring | Demolition of site buildings, final cover system installed over heap pile, groundwater monitoring | Restoration of groundwater, decommissioning of injection wells, removal of pipes and processing building |
| Status at End Use | Site permanently transferred to U.S. Department of Energy (DOE) for long-term care; annual inspections performed | Site permanently transferred to DOE for long-term care; annual inspections performed | Site released for unrestricted use when cleanup criteria are met |