IAEA-TECDOC-1403 The long term stabilization of uranium mill tailings Final report of a co-ordinated research project 2000–2004 August 2004 IAEA-TECDOC-1403 The long term stabilization of uranium mill tailings Final report of a co-ordinated research project 2000–2004 August 2004 The originating Section of this publication in the IAEA was: Waste Technology Section International Atomic Energy Agency Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria THE LONG TERM STABILIZATION OF URANIUM MILL TAILINGS IAEA, VIENNA, 2004 IAEA-TECDOC-1403. ISBN 92–0–108904–X ISSN 1011–4289 © IAEA, 2004 Printed by the IAEA in Austria August 2004 FOREWORD The IAEA attaches great importance to the dissemination of information that can assist Member States with the development, implementation, maintenance and continuous improvement of systems, programmes and activities that support the nuclear fuel cycle and nuclear applications. This includes managing the legacy of accidents and past practices, including that from uranium mining and milling. A comprehensive IAEA programme of work covers multiple aspects of environmental remediation: technical and non-technical factors, including costs, that influence environmental remediation strategies and pertinent decision making; site characterization techniques and strategies; assessment of remediation technologies; techniques and strategies for post-remediation compliance monitoring; special issues such as the remediation of sites with dispersed radioactive contaminations or mixed contamination by hazardous and radioactive substance and of uranium mining and milling sites. In the past, often little or no care was taken to isolate uranium mill tailings from the environment. In order to address the specific problems surrounding the disposal of uranium mill tailings, the IAEA developed a co-ordinated research project (CRP) in this area. CRPs are intended to bring together researchers from different Member States with the view to share and disseminate the experience in solving problems of common interest. The aim of the CRP on the long term stabilization of uranium mill tailings was to contribute to the development of conceptual, technical, and management solutions that: render tailings more inert over prolonged time-spans; render impounded materials and engineered structures stable; over prolonged time spans; minimize the need for active maintenance; can be applied in a remediation context; and support solutions that are technically and economically feasible. The IAEA wishes to express its thanks to all Chief Scientific Investigators and other contributors to the work. Special thanks are due S. Needham, Australia, who under contract provided a seed review of tailings disposal techniques, and to H. Cotzee and R. Gatzweiler, who reviewed an early draft. The IAEA officer responsible for this technical publication was W.E. Falck of the Division of Nuclear Fuel Cycle and Waste Management. EDITORIAL NOTE This publication has been prepared from the original material as submitted by the authors. The views expressed do not necessarily reflect those of the IAEA, the governments of the nominating Member States or the nominating organizations. The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights. CONTENTS 1. INTRODUCTION ............................................................................................................ 1 1.1. Background......................................................................................................... 1 1.2. Objectives ........................................................................................................... 2 1.2.1. Overall objective..................................................................................... 2 1.2.2. Scientific research objectives.................................................................. 3 1.3. The focus of the CRP.......................................................................................... 4 1.4. The structure of the CRP .................................................................................... 5 2. HISTORICAL PRACTICES ............................................................................................ 6 2.1. The ‘ages’ of uranium production ...................................................................... 6 2.2. Age, number, geographic and climatic distribution of uranium mill tailings piles........................................................................................................ 8 2.3. Relationship of tailings piles to mine and mill facilities .................................. 11 2.4. Historical approaches to tailings placements.................................................... 12 2.4.1. No effective containment...................................................................... 12 2.4.2. Low embankments................................................................................ 13 2.4.3. Topographic depressions ...................................................................... 13 2.4.4. Valley fill .............................................................................................. 13 2.4.5. Ring dyke or turkey nest dam............................................................... 13 2.4.6. Mined out pit......................................................................................... 13 2.4.7. Underground mine back-fill.................................................................. 14 2.4.8. Deep lake or river ................................................................................. 14 2.5. Classification of uranium mill tailings ............................................................. 14 2.6. Inappropriate uses of uranium mill tailings...................................................... 15 3. ENVIRONMENTAL IMPACTS ................................................................................... 16 3.1. Events that have led to environmental impacts ................................................ 16 3.2. Impacts on human health.................................................................................. 19 3.3. Potential radiological impacts upon the natural environment .......................... 21 3.4. Toxic and hazardous compounds in tailings and their potential impacts ......... 23 4. REMEDIATION PROGRAMMES TO REDUCE HAZARDS FROM HISTORICAL URANIUM MILL TAILINGS .............................................................. 24 4.1. Driving forces for remedial work ..................................................................... 24 4.2. Remedial work undertaken............................................................................... 25 4.3. Examples from the USA................................................................................... 26 4.4. Examples from France...................................................................................... 26 4.5. Examples from Germany.................................................................................. 26 4.6. Examples form the Czech Republic ................................................................. 26 4.7. Examples from Australia.................................................................................. 27 4.8. Evaluation of the remedial works at historic tailings piles............................... 27 5. PRESENT DAY PRACTICES....................................................................................... 28 5.1. Objectives ......................................................................................................... 28 5.2. Standards for radiological and environmental protection................................. 29 5.3. Member States’ regulations, standards and guidelines..................................... 30 5.4. Current approaches to tailings containment ..................................................... 32 5.4.1. Less-favoured options........................................................................... 32 5.4.2. Above ground disposal ......................................................................... 33 5.4.3. Below ground containment................................................................... 36 5.4.4. Deep lake .............................................................................................. 39 5.4.5. Purpose-built containment .................................................................... 39 5.5. Current approaches to stabilise and isolate uranium mill tailings .................... 40 5.5.1. Design objectives.................................................................................. 40 5.5.2. Containment preparation....................................................................... 40 5.5.3. Tailings preparation .............................................................................. 41 5.5.4. Tailings discharge and deposition......................................................... 43 5.5.5. Tailings consolidation..........................................................................