The Study of Alternate, Solid-Phase Fluorinating Agents for Use in Reactive Gas Recycle of Used Nuclear Fuel
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University of South Carolina Scholar Commons Theses and Dissertations 2013 The tudS y of Alternate, Solid-Phase Fluorinating Agents for Use in Reactive Gas Recycle of Used Nuclear Fuel Dillon Inabinett University of South Carolina Follow this and additional works at: https://scholarcommons.sc.edu/etd Part of the Nuclear Engineering Commons Recommended Citation Inabinett, D.(2013). The Study of Alternate, Solid-Phase Fluorinating Agents for Use in Reactive Gas Recycle of Used Nuclear Fuel. (Master's thesis). Retrieved from https://scholarcommons.sc.edu/etd/3587 This Open Access Thesis is brought to you by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. THE STUDY OF ALTERNATE, SOLID-PHASE FLUORINATING AGENTS FOR USE IN REACTIVE GAS RECYCLE OF USED NUCLEAR FUEL by Dillon Inabinett Bachelor of Science University of South Carolina, 2012 Submitted in Partial Fulfillment of the Requirements For the Degree of Master of Science in Nuclear Engineering College of Engineering and Computing University of South Carolina 2013 Accepted by: Travis W. Knight, Major Professor Joshua Gray, Second Reader Lacy Ford, Vice Provost and Dean of Graduate Studies © Copyright by Dillon Inabinett, 2013 All Rights Reserved. ii DEDICATION I would like to dedicate this work to my mother, for her endless support throughout all of my endeavors. Though life may not have always been perfect, the one thing that remains true is her love and affection. iii ACKNOWLEDGEMENTS I would like to thank my two advisors, Dr. Travis Knight and Dr. Joshua Gray for giving me the opportunity to work on this project. I could not have completed this research without their guidance and mentoring. Also, I would like to thank Dr. Brenda Garcia-Diaz, or “Momma Brenda,” for her support during my internship at SRNL. To my colleagues, I would like to thank you for your assistance in both classes and research. In particular, I thank Seung Min Lee for allowing me to use his TGA at USC for my experiments, Kyle Hrutkay who doubled as my gym buddy and listened to countless hours of venting not only about research, but life in general, and Kallie Metzger, who accompanied me on my first real plane ride to San Diego, CA to present my research at Winter ANS 2012. Finally, I would like to extend my thanks and deep appreciation to the NANT (National Academy for Nuclear Training) Fellowship for funding me throughout this research. iv ABSTRACT Surrogate oxides of the Used Nuclear Fuel (UNF) matrix were fluorinated using alternate, solid-phase fluorinating agents XeF2 and NH4HF2 to form volatile and non- volatile compounds and demonstrate the possibility of a chemical and thermal separations. A matrix of experiments was conducted at the milligram quantity scale using a Shimadzu DTG-60 TG/DTA installed at SRNL (Savannah River National Laboratory) for testing of all non-radioactive samples and a Netzsch STA 409 TGA installed in the laboratory at USC (University of South Carolina) for testing of all radioactive samples. The fluorination and subsequent volatilization potentials were analyzed by mixing excess fluorinating agent with a surrogate oxide at roughly a 2:1 ratio and then heated to elevated temperatures for analysis. Thermogravimetric and differential thermal analysis allowed for reaction pathways to be analyzed and suggest windows both thermally and chemically for separations of these various components. The differences in thermophysical properties of these products can be utilized as a starting point to effectively separate, isolate, and collect product streams with different product composition for further processing. The study of these chemistries could be incorporated into advanced separations methods to provide another possible solution for the long-term sustainability of nuclear power as the issue of reuse and disposal of commercial fuel continues to grow. v TABLE OF CONTENTS DEDICATION ....................................................................................................................... iii ACKNOWLEDGEMENTS ........................................................................................................ iv ABSTRACT ............................................................................................................................v LIST OF TABLES ................................................................................................................ viii LIST OF FIGURES ................................................................................................................. ix LIST OF ABBREVIATIONS .................................................................................................... xii CHAPTER 1: MOTIVATION.....................................................................................................1 CHAPTER 2: LITERATURE REVIEW ........................................................................................4 2.1 UNITED STATES CURRENT USED NUCLEAR FUEL POLICIES ..................................4 2.2 OVERVIEW OF THE PUREX PROCESS ....................................................................9 2.3 OVERVIEW OF FLUORIDE VOLATILITY.................................................................12 2.4 INVESTIGATION OF ALTERNATE FLUORINATING AGENTS ....................................15 CHAPTER 3: METHODOLOGY ..............................................................................................23 3.1 EXPERIMENTAL SETUP – NON RADIOACTIVE (SRNL) .........................................23 3.2 TG/DTA CALIBRATION (SRNL) .........................................................................26 3.3 SAMPLE PREPARATION (SRNL)...........................................................................31 3.4 EXPERIMENTAL SETUP – RADIOACTIVE (SRNL) .................................................32 3.5 EXPERIMENTAL SETUP (USC) .............................................................................33 3.6 SAMPLE PREPARATION (USC) .............................................................................38 CHAPTER 4: RESULTS AND DISCUSSION ..............................................................................41 vi 4.1 THERMAL DECOMPOSITION OF XEF2 ...................................................................41 4.2 THERMAL DECOMPOSITION OF NH4HF2 ..............................................................42 4.3 STRONTIUM OXIDE (SRO) ...................................................................................44 4.4 MOLYBDENUM TRIOXIDE (MOO3) .......................................................................54 4.5 NIOBIUM PENTOXIDE (NB2O5) .............................................................................60 4.6 RHODIUM (III) OXIDE (RH2O3) ............................................................................63 4.7 RUTHENIUM (IV) OXIDE (RUO2) .........................................................................66 4.8 ZIRCONIUM DIOXIDE (ZRO2) ...............................................................................69 4.9 URANIUM DIOXIDE (UO2) - SRNL ......................................................................71 4.10 TRIURANIUM OCTOXIDE (U3O8) - USC .............................................................74 CHAPTER 5: CONCLUSION AND FUTURE WORK ..................................................................82 REFERENCES .......................................................................................................................85 vii LIST OF TABLES Table 2.1 Composition of UNF ...........................................................................................5 Table 2.2 Current Reprocessing Strategies ..........................................................................6 Table 2.3 Results from Chandler Study ...............................................................................7 Table 2.4 Volatility of Various UNF Components ............................................................14 Table 2.5 Expected Fluorination Reactions with NF3 .......................................................17 Table 2.6 Reaction Onset and Volatilization Temperatures using NF3 .............................19 Table 3.1 XRD Instrument Parameters ..............................................................................26 viii LIST OF FIGURES Figure 2.1 Reaction Equations for PUREX Process ..........................................................10 Figure 2.2 Secondary Waste Alternatives for PUREX Process .........................................11 Figure 2.3 Flow Sheet for Fluoride Volatility Method ......................................................13 Figure 2.4 Basic Concept for HRS ....................................................................................15 Figure 2.5 Reaction of UO2 with NH4HF2 to Produce UN2 ..............................................20 Figure 2.6 Observations Using XeF2 as Fluorinating Agent .............................................22 Figure 3.1 Installation of DTG-60 .....................................................................................24 Figure 3.2 XRD Slide Preparation .....................................................................................25 Figure 3.3 Baseline Heating Results Prior to Adjustment .................................................27 Figure 3.4 Baseline Heating Results Post Adjustment ......................................................28 Figure 3.5 TG/DTA Data for Melting of Tin .....................................................................29