Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors Prepared for U.S. Department of Energy MSR Campaign B.J. Riley,(a) J. McFarlane,(b) G.D. DelCul,(b) J.D. Vienna,(a) C.I. Contescu,(b) L.M. Hay,(a) A.V. Savino,(a) H.E. Adkins,(a) (a)Pacific Northwest National Laboratory (b)Oak Ridge National Laboratory August 15, 2018 NTRD-MSR-2018-000379, PNNL-27723 Approved for public release. Distribution is unlimited. DISCLAIMER This information was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness, of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, trade mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors iv August 15, 2018 SUMMARY The overall summary of the waste management envelope discussed in this report is represented by the diagram shown in Figure S1. The streams that are included in this discussion include the following from reactor systems in which chlorine-based salts with and without processing and fluorine-based salts with and without processing are being considered: 1) Off-gas streams (e.g., particulates, aerosols, reactive gases, 3H, water, residual halides, N2, O2, noble gases) 2) Salt waste streams (e.g., chloride- or fluoride-based) 3) Separated salt streams (e.g., 7Li recycle, 37Cl recycle, eutectic salts, fission products) 4) Metal waste streams (e.g., reactor components, plenums) 5) Carbon waste streams (e.g., graphite, SiC) 6) Decommissioning and decontaminating (D&D) waste streams 7) Operating waste streams Figure S1. Summary of waste management categories for molten salt reactor program. The goals of this report are to accomplish the following: Assess the potential waste streams that could be generated from molten salt reactor processes Determine how these wastes could be treated and/or immobilized in a form that could be disposed of Determine the storage, transportation, and disposal requirements for molten salt reactor wastes Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors August 15, 2018 v ACKNOWLEDGEMENTS The authors would like to thank the Department of Energy Office of Nuclear Energy’s, Office of Advanced Reactor Technology for funding this work under the Nuclear Technology Research and Development Program. The authors would also like to thank Lou Qualls (ORNL), Stephen Kung (DOE- NE), and Brian Robinson (DOE-NE) for project oversight and guidance. Authors would like to thank Steve Frank (INL), Guy Fredrickson (INL), Ken Marsden (INL), David Holcomb (ORNL), Ben Betzler (ORNL), Jim Jerden (ANL), Charles Forsberg (MIT), and Ted Besmann (USC) for helpful discussions related to this work. Gary Sevigny (PNNL) supplied many helpful suggestions during document review. The Pacific Northwest National Laboratory is operated by Battelle under contract DE-AC05-76RL01830. The Oak Ridge National Laboratory is operated by UT-Battelle, LLC, under contract DE-AC05- 00OR22725. Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors vi August 15, 2018 CONTENTS SUMMARY ................................................................................................................................................. iv ACKNOWLEDGEMENTS .......................................................................................................................... v ABBREVIATIONS AND ACRONYMS ................................................................................................... xii 1. INTRODUCTION .............................................................................................................................. 2 2. WASTE STREAM POSSIBLITIES .................................................................................................. 5 2.1 Volatile Off-Gas Waste Streams .............................................................................................. 5 2.2 Unseparated Salt Waste Streams .............................................................................................. 6 2.3 Salt Separations Streams .......................................................................................................... 7 2.4 Carbon Streams ........................................................................................................................ 8 2.5 Metal-Based Waste Streams .................................................................................................. 10 2.6 Streams from Decommissioning and Decontaminating ......................................................... 11 2.7 Streams for Operating Wastes ................................................................................................ 12 3. OPTIONS FOR OFF-GAS PRODUCTS ......................................................................................... 13 3.1 Particulates, Aerosols, and Reactive Gases ............................................................................ 15 3.2 Tritium (3H) ............................................................................................................................ 15 3.3 Residual Halides .................................................................................................................... 17 3.4 Nitrogen and Oxygen ............................................................................................................. 18 3.5 Noble Gases ........................................................................................................................... 18 3.6 Caustic Scrubbing .................................................................................................................. 21 3.7 Volatile Uranium and Transuranics ....................................................................................... 22 3.7.1 Volatile Fluorides ...................................................................................................... 22 3.7.2 Volatile Chlorides ..................................................................................................... 25 3.7.3 Interconversion of Chlorides and Fluorides .............................................................. 29 4. OPTIONS FOR UNSEPARATED AND SEPARATED SALTS .................................................... 30 4.1 Mineral Waste Forms ............................................................................................................. 30 4.2 Waste Form Options Based on Salt Type .............................................................................. 30 4.2.1 Options for Fluoride-Based Waste Components ....................................................... 30 4.2.2 Options for Chloride-Based Waste Components ...................................................... 34 4.3 Nonspecific Waste Form Options .......................................................................................... 35 4.3.1 Glasses ...................................................................................................................... 35 4.3.2 Ceramic-Metal (Cermet) Composites ....................................................................... 36 4.3.3 Dehalogenation of Salts Using Phosphate Precursors............................................... 37 4.3.4 Dehalogenation of Salt through Reaction with Ultrastable H-Y Zeolite .................. 42 4.4 Separations and Products of Separations ............................................................................... 43 4.4.1 Oxidative Precipitation ............................................................................................. 43 4.4.2 Reactive Distillation .................................................................................................. 45 4.4.3 Vacuum Distillation .................................................................................................. 46 4.4.4 Melt Crystallization................................................................................................... 47 Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors August 15, 2018 vii 4.4.5 Metal Transfer Process .............................................................................................. 48 4.5 Lithium-7 (7Li) Recovery Options for Fluoride Salt Systems ............................................... 51 4.6 Chlorine-37 (37Cl) Recovery Options for Chloride Salt Systems .......................................... 52 5. OPTIONS FOR CARBON-BASED WASTES ............................................................................... 53 5.1 EU CARBOWASTE Program ............................................................................................... 54 5.2 Graphite Recycle .................................................................................................................... 54 5.3 Spent Nuclear Fuel from FHRs .............................................................................................