NUREG/CR-6733 A Baseline Risk-Informed, Performance-Based Approach for In Situ Leach Uranium Extraction Licensees Center for Nuclear Waste Regulatory Analyses U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards Washington, DC 20555-0001 .oG.o AVAILABILITY OF REFERENCE MATERIALS IN NRC PUBLICATIONS NRC Reference Material Non-NRC Reference Material As of November 1999, you may electronically access Documents available from public and special NUREG-series publications and other technical NRC records at libraries include all open literature items, such as NRC's Public Electronic Reading Room at books, journal www.nrc.gov/NRC/ADAMS/index.html. articles, and transactions, Federal Register notices, Federal and State legislation, and Publicly released records include, to name a few, congressional reports. 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NUREG/CR-6733 A Baseline Risk-Informed, Performance-Based Approach for In Situ Leach Uranium Extraction Licensees Manuscript Completed: June 2001 Published: September 2001 Prepared by 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 Prepared for 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 NUREG/CR-6733 has been reproduced from the best available copy. ABSTRACT 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 (U30.) 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. iii CONTENTS Section Page A B STRA CT ........................................................................ iii FIG U R E S .......................................................................... ix TA B L E S .......................................................................... xi ACKNOW LEDGM ENTS ............................................................ xiii INTRODUCTION ........................................................... 1-1 2 DESCRIPTION OF IN-SITU LEACH FACILITY OPERATIONS ...................... 2-1 2.1 URANIUM EXTRACTION FROM THE ORE BODY ........................ 2-1 2.2 OPERATIONS IN THE PROCESSING PLANT ............................. 2-6 2.2.1 Ion Exchange .................................................. 2-6 2.2.2 Elution ........................................................ 2-8 2.2.3 Precipitation and Drying .......................................... 2-8 2.3 AQUIFER RESTORATION ............................................. 2-9 2.3.1 Groundwater Sweep ............................................ 2-10 2.3.2 Reverse Osmosis with Permeate Injection ........................... 2-10 2.3.3 Recirculation .................................................. 2-12 2.3.4 Stabilization .................................................. 2-12 2.4 INSTRUMENTATION ................................................ 2-12 2.5 WASTE MANAGEMENT ............................................. 2-13 2.5.1 Liquid W aste Disposal .......................................... 2-13 2.5.2 Solid Effluent W aste Disposal .................................... 2-14 2.5.3 Gaseous Effluent and Airborne Particulate Waste Disposal ............. 2-14 2.6 RECLAMATION, DECONTAMINATION, AND DECOMMISSIONING ....... 2-15 2.7 MANAGEMENT CONTROLS AND OPERATING PROCEDURES ............ 2-17