INL/EXT-20-59106 Review – Nuclear Fuels and Reprocessing Technologies: A U.S. Perspective March 2021 Guy Fredrickson Tae-Sic Yoo 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, trademark, 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. INL/EXT-20-59106 Review – Nuclear Fuels and Reprocessing Technologies: A U.S. Perspective Guy Fredrickson Tae-Sic Yoo March 2021 Idaho National Laboratory Pyrochemistry & Molten Salt Systems Department Idaho Falls, Idaho 83415 http://www.inl.gov Prepared for the U.S. Department of Energy Office of Nuclear Energy Under DOE Idaho Operations Office Contract DE-AC07-05ID14517 Page intentionally left blank ABSTRACT Reprocessing and/or waste management issues are of concern to the “back end” of the nuclear fuel cycle. Of course, there are a great many “nuclear fuel cycle” scenarios to consider; if not in practice, then at least in theory. The simplest conceptually is the “once through” fuel cycle in which the spent fuel is discarded. The more complex fuel cycle scenarios involve reprocessing spent nuclear fuels and a family of nuclear reactor technologies to accommodate burning and breeding for various military and commercial needs. Therefore, the selection of a specific “fuel cycle” is what ultimately imposes the engineering requirements of the reprocessing and waste management technologies. No one part is independent of the other parts in a fuel cycle flowsheet; all parts should be fully integrated. This paper presents a summary of nuclear chemistry processes, nuclear reactor technologies, associated nuclear fuel types, and the reprocessing technologies that serve the different nuclear fuel types. Comprehending how this series of topics are related to each other is a prerequisite to understanding the requirements of any reprocessing strategy. The summary materials presented here are selective, as opposed to comprehensive. More detailed information on any one subject can be found in the reference materials. iii Page intentionally left blank iv CONTENTS 1. INTRODUCTION ............................................................................................................................... 1 2. MATERIALS BACKGROUND ......................................................................................................... 1 2.1 Mining and Extraction of Uranium and Thorium .................................................................... 5 2.2 Uranium, Lithium, Chlorine, and Nitrogen Enrichment .......................................................... 5 2.3 Hydrogen .................................................................................................................................. 7 2.4 Krypton, Xenon, and Iodine Fission Products ......................................................................... 7 2.5 Burnable Poisons/Neutron Absorbers ...................................................................................... 8 2.6 Neutron Moderators and Reflectors ......................................................................................... 9 3. NUCLEAR REACTORS .................................................................................................................. 10 4. NUCLEAR FUELS ........................................................................................................................... 13 4.1 Nuclear Fuel Taxonomy ......................................................................................................... 14 4.2 Natural Uranium Oxide Fuel .................................................................................................. 18 4.3 Low Enriched Uranium Oxide Fuel ....................................................................................... 18 4.4 Mixed Oxide Fuel .................................................................................................................. 19 4.5 Natural Uranium Metal Fuel .................................................................................................. 20 4.6 Sodium-Bonded Metallic Fuel ............................................................................................... 23 4.7 Research Reactor Dispersion Fuel ......................................................................................... 24 4.8 Coated-Particle Dispersion Fuel ............................................................................................ 26 4.9 Naval Reactor Fuel ................................................................................................................. 28 4.10 Inert Matrix Fuel .................................................................................................................... 29 4.11 Molten Salt Fuel ..................................................................................................................... 30 5. REPROCESSING ............................................................................................................................. 32 5.1 Aqueous-Based Reprocessing Technologies ......................................................................... 33 5.2 Non-aqueous Reprocessing Technologies ............................................................................. 38 5.3 ORNL MSBR Salt Processing ............................................................................................... 45 5.4 Chloride Volatility Processes ................................................................................................. 46 5.5 Fluoride Volatility Processes ................................................................................................. 46 5.6 Fluoride Salt Electrowinning (Hall-Héroult Analog) ............................................................. 47 5.7 Mercury Amalgamation Processes ......................................................................................... 48 5.8 Salt Cycle Process .................................................................................................................. 48 5.9 Salt Transport Process ............................................................................................................ 49 5.10 Two Phase Exchange Processes ............................................................................................. 49 5.11 Processes Applied to TRISO-Type Fuels .............................................................................. 50 v 5.12 Weapons Plutonium Refining ................................................................................................ 50 6. EFFECT OF REPROCESSING EFFICIENCY ................................................................................ 52 6.1 The Importance of Maximizing the Retention of Fissile Materials ....................................... 53 6.2 The Importance of Maximizing the Rejection of Fission Products........................................ 54 6.3 Remarks on the Abstracted Fuel Cycle Models ..................................................................... 56 6.4 The Considerations of Fundamental Complexities ................................................................ 57 7. CONCLUSIONS ............................................................................................................................... 58 8. REFERENCES .................................................................................................................................. 59 FIGURES Figure 1. Cascade of gas centrifuges at Piketon, Ohio. DOE. ...................................................................... 6 Figure 2. Photograph of CANDU reactor fuel bundle. A typical CANDU fuel bundle is about 0.1-m-diameter and 0.5-m-length, and weighs about 24 kg. This bundle appears to contain 37 fuel elements in sequential layers of 18, 12, 6, and 1. .............................................. 18 Figure 3. Photograph of PWR fuel assembly. Typical PWR and BWR grids are square and contain 14 to 18 and 8 to 10 fuel elements per row, respectively. The square dimensions range from about 0.14 to 0.23 m, lengths from 3.9 to 4.8 m, and weights from 500 to 700 kg. Enrichment levels range up to about 5 wt% 235U. ...................................... 19 Figure 4. Photograph of BN-800 Reactor fuel assemblies, Beloyarsk Nuclear Power Station, Sverdlovsk Oblast, Russia. MOX fuel clad in stainless steel. The BN-800 reactor is an SFR. ............................................................................................................................................ 20 Figure 5. Photograph of Ohma Nuclear Power Plant fuel assembly, Aomori Prefecture, Japan. MOX fuel clad in zirconium alloy. The Ohma reactor is an ABWR. ........................................ 20 Figure 6. Photograph of typical Hanford Reactor fuel elements (single-pass-coolant reactor design). Single extruded tube of NU clad in aluminum