This review is based on Miller-Corbett et al. (1992).
The regulation of ISL mines in the United States is controlled by the US Nuclear Regulatory Commission (USNRC) in conjunction with specific state requirements. Under the direction of the US Congress, the USNRC administers the Atomic Energy Act 1954, as amended, and Titles I and II of the Uranium Mill Tailings Radiation Control Act (UMTRCA) 1978, as amended.
Any proponent of a new ISL uranium project must submit a licence application in conjunction with an Environmental Report (ER). The ER must characterise the proposed ISL site, processing facility, operational plans, environmental protection and management plans and a radiation safety plan. The ER must also contain plans for the post-mining restoration of groundwater at the site, land reclamation and plant decommissioning. The proponent, through the ER, must demonstrate that the proposal will not cause harm to human health or the environment.
The information presented in the ER forms the basis for the NRC’s preparation of an Environmental Assessment (EA) and Safety and Evaluation Report (SER).
The EA comprises an evaluation of the potential environmental impacts of a proposed ISL facility. In compliance with the National Environmental Policy Act (NEPA), if the conclusion of the EA is that there will be no impact to the environment, the USNRC publishes a Finding of No Significant Impact. Publication in the Federal Register provides notice to the public, and solicits comments with regards to the proposed project. If the USNRC finds a significant impact may occur as a result of proposed facility operations, a more detailed document, and Environmental Impact Statement is required, a publicly released document.
The SER is an evaluation of the prospective workforce and site occupant radiation safety at an ISL facility. This evaluation is based on proposed site operations and the predicted sources of accompanying radiation hazards. The SER includes a description of the applicant’s radiation safety program to limit radiation exposure from gamma emitters as well as ingestion and inhalation of airborne radionuclides. The SER also includes a description of an in-plant monitoring program to ensure that the workers’ environment is adequately characterised.
An ISL mine operator is required to provide proof of financial surety arrangements prior to commencement of operations. This requirement assures that there are sufficient funds available for decontamination, decommissioning and reclamation of the facility in the event that the operator is incapable of performing these tasks.
The ER covers important environmental information, including geography, demographics, geology, hydrology and local meteorology. The site must also undergo detailed characterisation, such as aquifer flow properties, and define the mineralised zone and all aquitards (confining units) and aquifers above and below the ore zone. Another critical factor is the collection of baseline groundwater quality data before mining begins. These need to be statistically derived and are used in later groundwater monitoring to determine if there is control of leaching solution flow. The baseline data is also critical in determining the requirements for groundwater quality restoration. The USNRC also requires that detailed assessment of airborne radioactive emissions be characterised and their impact on surrounding human health and the environment quantitatively modelled (using the MILDOS system). They must include all sources and vents of radon gas, uranium dust and other radionuclide emissions.
In addition, the USNRC requires that prospective licencees prepare Standard Operating Procedures (SOP) for all work involving radioactive materials. The SOP’s must be available at all times and to all employees. Similar procedures are required for all equipment and programs developed for environmental protection and monitoring.
The reclamation of a former ISL mine site must include the decontamination of all buildings, foundations, and equipment prior to release to unrestricted areas. Alternatively, contaminated materials may be transferred to another licencee for radioactive source materials (eg - an ISL mine site). All injection, extraction and monitoring wells must be cut off below the surface and appropriately abandoned to prevent cross contamination of aquifers.
The radioactive wastes, such as piping, contaminated soils, and decommissioned equipment, must be disposed of at facilities licensed for such material. Currently, tailings piles at conventional uranium mills serve as receptors, although state facilities are also acceptable. All waste waters are generally required to be evaporated, unless the operator holds a permit from the USEPA for deep well disposal.
An issued In Situ Mining Licence is generally for 5 to 7 years, and need to be renewed near the end of this period. At this time, a new Environmental Report must be submitted detailing the operating history of the ISL mine and address any significant changes from the previous licence approval. A licence amendment may also be considered, covering aspects such as process plant alterations, environmental management plans or corporate organisation. An updated financial surety arrangement must also be included.
There are also state specific regulatory requirements that must be met before an ISL proposal is able to commence construction and operation. A review of Wyoming and Texan regulations are provided in their respective sections.
Upon meeting all of the above regulatory requirements, an applicant receives a source material licence authorising operation the proposed ISL facility.