Prepared in cooperation with the U.S. Department of Energy under Interagency Agreement DE-Al28-07RW12405 Analogues to Features and Processes of a High- Level Radioactive Waste Repository Proposed for Yucca Mountain, Nevada Professional Paper 1779 U.S. Department of the Interior U.S. Geological Survey Analogues to Features and Processes of a High-Level Radioactive Waste Repository Proposed for Yucca Mountain, Nevada By Ardyth M. Simmons, Los Alamos National Laboratory, Los Alamos, New Mexico, and John S. Stuckless, U.S. Geological Survey, Denver, Colorado, with a Foreword by Abraham Van Luik, U.S. Department of Energy Prepared in cooperation with the U.S. Department of Energy under Interagency Agreement DE-AI28-07RW12405 Professional Paper 1779 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2010 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Simmons, A.M., and Stuckless, J.S., 2010, Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada: U.S. Geological Survey Professional Paper 1779, 195 p. Library of Congress Cataloging-In-Publication Data Simmons, Ardyth M. Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada / by Ardyth M. Simmons, and John S. Stuckless ; with a foreword by Abraham Van Luik. p. cm. Includes bibliographical references. ISBN 978-1-4113-2945-4 (pbk.) 1. Geological repositories. 2. Radioactive waste disposal in the ground--Nevada--Yucca Mountain. 3. Seepage. 4. Soil chemistry. I. Stuckless, John S. II. Title. TD1064.S56 2010 621.48’380979334--dc22 2010032980 iii Foreword The presentation of analogues in this report is a culmination of years of work by a number of persons who searched for analogues for features, materials, and processes likely to be found in, and determining aspects of the behavior of, a repository for high-level radioactive waste in thick, unsaturated tuffs proposed at Yucca Mountain in Nevada. The analogues discussed provide valuable scientific and technical insight into the functioning of a high-level radioactive waste repository in a semiarid, unsaturated, fractured-rock environment. The analogues presented will have a variety of applications, such as tunnel excavation in fractured unsaturated media, either for transport or storage of materials or energy. As noted in the Introduction, other repository programs throughout the world have been actively involved in identifying natural and anthropogenic analogues. Most of the international programs are considering a repository site in saturated rock, away from oxidizing groundwater, for which numerous analogues exist in roll-front uranium and other types of ore deposits. For a repository in unsaturated rock with oxidizing groundwater conditions, the search for analogues is more challenging. Therefore, this document is a fitting supplement to the excellent compendia on natural analogues that have been published by several national programs and by international organizations, especially the European Commission. Beyond the need for the United States’ high-level radioactive waste respository, society is likely to require the future disposal of wastes from more advanced nuclear fuel cycles, which are currently undergoing research and development. These differing waste streams will bring new challenges and new opportunities for appropriate analogues. This report provides a useful basis for these future needs. Abraham Van Luik, U.S. Department of Energy iv Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Preservation Within the Unsaturated Zone ...............................................................................................7 Natural Caves and Rock Shelters ......................................................................................................9 Manmade Openings ...........................................................................................................................14 Dryness and Preservation .................................................................................................................18 Evaluation of Analogues for Preservation in the Unsaturated Zone ..........................................18 Repository Drift Stability Analogues .........................................................................................................19 Repository Design Selection and Relation to Applicable Analogues ........................................19 Drift-Stability Analogues ...................................................................................................................22 Stability of Natural Underground Openings ..........................................................................23 Stability of Manmade Underground Openings .....................................................................28 Response of Caves to Seismicity ............................................................................................35 Response of Manmade Underground Openings to Seismicity ..........................................38 Underground Openings Affected by Temperature ...............................................................41 Summary of Drift Stability Analogues .............................................................................................41 Analogues for the Engineered Barrier System .......................................................................................41 Waste-Form Degradation ..................................................................................................................42 Overview of Conceptual Basis of Waste-Form Degradation ..............................................42 Spent-Fuel Dissolution in an Oxidizing Environment ...........................................................43 Analogue Studies Related to Waste-Form Dissolution Rates ............................................45 Analogue Studies Related to Immobilization by Secondary Minerals ..............................47 Radiolysis .............................................................................................................................................49 Criticality...............................................................................................................................................50 Nuclear Waste Glass Analogues .....................................................................................................51 Summary of Waste-Form Analogues ...............................................................................................53 Engineered Barrier System Design .................................................................................................54 Waste-Package Degradation Analogues .......................................................................................60 Natural Analogue Studies of Corrosion .................................................................................61 Passive Film Formation ....................................................................................................63 Naturally Occurring Metals as Natural Analogues ....................................................63 Summary of Waste-Package Degradation Analogues ........................................................65 Analogues for Other Engineered Barrier System Components and Their Effect on Radionuclide Transport ........................................................................................................65 Analogues for the Titanium Drip Shield .................................................................................68 Analogues for the Invert Ballast .............................................................................................68 Natural Analogues for Development of Alkaline Plumes from Cement .....................................69 Natural Analogues for Colloidal Transport of Radionuclides in the Near Field........................70 Summary of Analogues to Engineered Barrier System Materials and Processes ..................71 Seepage Analogues ....................................................................................................................................71 Seepage Characteristics of Caves ..................................................................................................72 Seepage Characteristics of Underground Openings ....................................................................74