E5-2073. Draft Report for Comment: “Consideration of Geochemical Issues in Groundwater Restoration at Uranium In-Situ Leach Mining Facilities,” NUREG/CR-6870

AGENCY:

Nuclear Regulatory Commission.

ACTION:

Notice of availability and request for comments.

Background: Some mining processes use fluids to dissolve (or leach) a mineral without the need to remove physically the ore containing the mineral from an ore deposit in the ground. In general, these “in-situ” leach mining operations at uranium mines are considerably more environmentally benign than traditional mining and milling of uranium ore. Nonetheless, the use of leaching fluids to mine uranium may contaminate the groundwater aquifer in and around the region from which the uranium is extracted. The U.S. Nuclear Regulatory Commission (NRC) requires licensees to restore the aquifer to established water-quality standards following the cessation of in-situ leach mining operations.

The NRC also requires licensees to ensure that sufficient funds will be available to cover the cost of decommissioning their facilities. For these uranium mines, restoration generally consists of pumping specially treated water into the affected aquifer and removing the displaced water—and thereby the undesirable contaminants—from the system. Because groundwater restoration can represent approximately 40 percent of the cost of decommissioning a uranium leach mining facility, a good estimate of the necessary volume of treatment water is important to estimate the cost of decommissioning accurately.

The subject report, prepared for the NRC by the U.S. Geological Survey, summarizes the application of a geochemical model to the restoration process to estimate the degree to which a licensee has decontaminated a site where a leach mining process has been used. Toward that end, this report analyzes the respective amounts of water and chemical additives pumped into the mined regions to remove and neutralize the residual contamination using 10 different restoration strategies. The analyses show that strategies that used hydrogen sulfide in systems with low natural oxygen content provided the best results. On the basis of those findings, this report also summarizes the conditions under which various restoration strategies will prove successful. This, in turn, will allow more accurate estimates of restoration and decommissioning costs.

The subject report will be useful for licensees and State regulators overseeing uranium leach mining facilities, who need to estimate the volume of treatment water needed to decontaminate those facilities.

Solicitation of Comments: The NRC seeks comments on the report and is especially interested in comments on the utility and feasibility of the modeling techniques described in the report.

Comment Period: The NRC will consider all written comments received before June 17, 2005. Comments received after July 17, 2005, will be considered if time permits. Comments should be addressed to the contact listed below.

Availability: An electronic version of the report is available in Adobe Portable Document Format at http://www.nrc.gov/​reading-rm/​doc-collections/​nuregs/​contract/​cr6870/​cr6870.pdf and can be read with Adobe Acrobat Reader software, available at no cost from http://www.adobe.com. Hard and electronic copies are available from the contact listed below.

FOR FURTHER INFORMATION CONTACT:

Dr. John D. Randall, Mail Stop T9C34, U.S. Nuclear Regulatory Commission, 11545 Rockville Pike, Rockville, MD 20852, telephone [phone], e-mail [e-mail].

Dated at Rockville, Maryland, this 20th day of April 2005.

For the Nuclear Regulatory Commission.

Cheryl A. Trottier,

Chief, Radiation Protection, Environmental Risk & Waste Management Branch, Division of Systems Analysis and Regulatory Effectiveness, Office of Nuclear Regulatory Research.