A Baseline Risk-Informed, Performance-Based Approach for In Situ Leach Uranium Extraction Licensees (NUREG/CR-6733)
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Manuscript Completed: June 2001
Date Published: September 2001
P. C. Mackin, D. Daruwalla, J. Winterle,
M. Smith, D. A. Pickettt
Center for Nuclear Waste Regulatory Analyses
6220 Culebra Road
San Antonio, TX 78228-0510
M. Layton, NRC Project Manager
Division of Fuel Cycle Safety and Safeguards
Office of Nuclear Material Safety and Safeguards
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
NRC Job Code J5220
Existing U.S. Nuclear Regulatory Commission (NRC) regulations are not specifically applicable to uranium recovery facilities. Appendix A to 10 CFR Part 40 provides criteria for the operation of conventional uranium mills and for the disposition of their tailings or wastes; however, technology for in situ leaching (ISL) of uranium, which comprises the majority of current uranium extraction operations in the United States, for the most part evolved subsequent to the promulgation of 10 CFR Part 40.
The technology for the extraction of uranium using ISL techniques allows economical recovery of uranium from lower grade ores and causes less environmental disruption than conventional extraction and milling. The final stages of the ISL process produce yellowcake (U308) using the same drying process employed by conventional uranium mills. Other aspects of the ISL process are substantially different from conventional uranium ore processing.
Current NRC regulations specifically applicable to uranium extraction at 10 CFR Part 40, Appendix A implement U.S. Environmental Protection Agency (EPA) regulations at 40 CFR Part 192. The current regulations address yellowcake drying and the wastes produced from ISL operations but do not govern other aspects of the ISL process, including the restoration of groundwater contaminated by these operations.
The NRC is implementing Direction Setting Issue 12 of its Strategic Reassessment and Rebaselining Initiative to employ risk-informed, performance-based (RIPB) regulatory programs that consider, among other factors, the degree of risk associated with specific operations in defining the nature of the applicable regulatory requirements. These regulatory programs typically identify performance measures as the basis for regulatory requirements.
The NRC staff tasked the Center for Nuclear Waste Regulatory Analyses (CNWRA) to develop a RIPB foundation for regulating ISL facilities. This report presents the results from that effort. The CNWRA used commonly accepted practices for hazard identification, consequence analysis, and risk assessment to define risks associated with ISL facility operations. The report examines operations for extracting and processing uranium into yellowcake, restoring groundwater quality subsequent to ore extraction, and health and environmental hazards and risks. Where possible, quantitative and probabilistic methods were used. The CNWRA used staff with expertise in dose assessment and health physics; process engineering; groundwater science and engineering; geochemistry; systems analysis and risk assessment; probabilistic and statistical analysis; identification, analysis, management, and evaluation of risk; and NRC regulation of source and 1 e.(2) byproduct material to complete this assessment. The CNWRA also collaborated closely with NRC staff experienced in ISL facility licensing.