Advances in Nuclear Fuel Chemistry (Woodhead Publishing Series in Energy)

Advances in Nuclear Fuel Chemistry presents a high-level description of nuclear fuel chemistry based on the most recent research and advances. Dr. Markus H.A. Piro and his team of global, expert contributors cover all aspects of both the conventional uranium-based nuclear fuel cycle and non-conventional fuel cycles, including mining, refining, fabrication, and long-term storage, as well as emerging nuclear technologies, such as accident tolerant fuels and molten salt materials. Aimed at graduate students, researchers, academics and practicing engineers and regulators, this book will provide the reader with a single reference from which to learn the fundamentals of classical thermodynamics and radiochemistry. Consolidates the latest research on nuclear fuel chemistry into one comprehensive reference, covering all aspects of traditional and non-traditional nuclear fuel cycles Includes contributions from world-renowned experts from many countries representing government, industry and academia Covers a variety of fuel designs, including conventional uranium dioxide, mixed oxides, research reactor fuels, and molten salt fuels Written by experts with hands-on experience in the development of such designs Front Cover Advances in Nuclear Fuel Chemistry Copyright Page Contents List of contributors About the editor Preface A. Fundamentals 1 Reaction kinetics and chemical thermodynamics of nuclear materials 1.1 Introduction 1.2 Basic concepts of chemical kinetics 1.2.1 Reaction rates 1.2.2 Temperature dependence of rate constants 1.3 Fundamentals of chemical thermodynamics 1.3.1 Thermodynamic system and state functions 1.3.2 The laws of thermodynamics 1.3.2.1 First law of thermodynamics 1.3.2.2 Second law of thermodynamics 1.3.2.3 Third law of thermodynamics 1.3.2.4 Zeroth law of thermodynamics 1.3.3 Enthalpy, Helmholtz, and Gibbs energies 1.3.3.1 Enthalpy 1.3.3.2 Helmholtz energy 1.3.3.3 Gibbs energy 1.3.4 Heat capacity 1.3.5 Thermodynamic relations between state functions 1.4 Thermodynamics of condensed phases 1.4.1 Molar thermodynamic properties 1.4.1.1 Definition of the reference and standard states 1.4.1.2 Enthalpy of formation 1.4.1.3 Standard entropy 1.4.1.4 Heat capacity at low temperatures (T 298.15K) 1.4.1.6 Gibbs energy of formation 1.4.2 Definition of the chemical potential 1.4.2.1 General definition 1.4.2.2 Chemical potential of an ideal single-component gas 1.4.2.3 Chemical potential of a single-component condensed phase 1.4.3 Mixing properties for gas, solid, and liquid solutions 1.4.3.1 Definition of a chemical solution 1.4.3.2 Chemical potential of a gas in solution 1.4.3.3 Chemical potential of species in solid and liquid solutions 1.4.3.4 Raoult’s law and Henry’s law, and standard states for a solution 1.4.3.5 Mixing and excess thermodynamic properties in solution 1.4.4 Chemical reaction equilibria 1.4.4.1 Equilibrium constant 1.4.4.2 Van’t Hoff equation 1.5 Statistical thermodynamics applied to gases 1.5.1 Statistical thermodynamic basis 1.5.1.1 The Boltzmann distribution law 1.5.1.2 Ensembles and probabilities 1.5.1.3 The canonical partition function 1.5.1.4 The relation between Z and z 1.5.1.5 The thermodynamic functions 1.5.2 Molecular thermodynamic calculations (ideal gas) 1.5.2.1 The translational partition function 1.5.2.2 The electronic partition function 1.5.3 The vibrational partition function 1.5.3.1 The rotational partition function 1.5.3.2 Coupling of internal motion 1.5.3.3 Hindered rotation 1.5.3.4 Limitations of the rigid rotor/harmonic oscillator model 1.5.3.5 Case studies 1.6 Thermodynamics of nuclear fuel and fission products 1.6.1 Phase diagrams 1.6.1.1 Gibbs phase rule 1.6.1.2 Terminology and lever rule 1.6.2 Melting transition 1.6.3 Effect of nonstoichiometry on thermodynamic properties 1.6.4 Sublimation and vaporization behavior 1.6.5 Chemical state of fission products: Ellingham diagrams 1.7 Solution thermodynamics applied to the storage of spent fuel and geological disposal 1.7.1 Hydrolysis and complexation 1.7.2 Solubility and precipitation 1.8 Basics of redox equilibria 1.8.1 Redox equilibria and Galvanic cell 1.8.1.1 Gibbs energy of the redox reaction and Nernst equation 1.8.2 Pourbaix diagrams 1.8.3 Speciation diagrams 1.9 Conclusion Acknowledgment References Further reading 2 Experimental methods 2.1 Introduction 2.2 Thermal analysis methods 2.2.1 Differential scanning and drop calorimetry 2.2.1.1 Differential scanning calorimetry Melting point determination Phase equilibria in binary mixtures Enthalpy of transition Enthalpy of mixing Heat capacity Continuous method Step method 2.2.1.2 Drop calorimetry 2.2.2 Thermogravimetric analysis 2.2.3 Laser heating 2.3 Spectroscopy techniques 2.3.1 Vibrational spectroscopy methods 2.3.2 X-ray absorption spectroscopy (EXAFS, XANES) 2.3.3 Photoelectron spectroscopy (XPS, UPS) 2.3.4 Electron microscopy and spectroscopy (SEM, TEM, EDS, EELS, EPMA) 2.3.4.1 Scanning electron microscopy and transmission electron microscopy 2.3.4.2 Electron probe microanalysis 2.3.5 Positron annihilation spectroscopy 2.4 Nuclear magnetic resonance 2.4.1 Liquid state nuclear magnetic resonance 2.4.2 Low-temperature nuclear magnetic resonance 2.4.3 High-resolution solid-state nuclear magnetic resonance 2.4.4 Some examples of nuclear magnetic resonance spectra acquired at JRC-Karlsruhe 2.5 Mass spectrometry techniques 2.5.1 Knudsen effusion mass spectrometry 2.6 Secondary ions mass spectrometry 2.7 Diffraction techniques 2.7.1 X-ray diffraction 2.7.2 Electron diffraction 2.8 Electrochemical techniques 2.8.1 Electromotive force and coulometry 2.9 Conclusion References Further reading 3 Computational thermochemistry of nuclear fuel 3.1 Introduction 3.2 Fundamentals 3.2.1 Thermodynamic laws 3.2.2 Derivation of fundamental thermodynamic properties 3.2.3 Conditions for equilibrium in a closed isothermal–isobaric system 3.2.3.1 Necessary conditions 3.2.3.2 Sufficient conditions 3.2.4 Gibbs energy minimization 3.3 The CALPHAD method 3.4 Applications and limitations of computational thermodynamics 3.4.1 Phase diagram construction 3.4.1.1 Binary phase diagrams 3.4.1.2 Ternary phase diagrams 3.4.1.3 Pourbaix diagrams 3.4.2 Integral analyses 3.4.3 Limitations of thermodynamic calculations 3.5 Summary References B. Fuel Designs 4 Oxide power reactor fuels 4.1 Introduction 4.1.1 Crystal structures of various oxide nuclear fuels 4.1.2 Nuclear reactions 4.1.3 Thermal conductivity profiles for the U–Pu–Th–O system 4.2 Phase diagrams involving UO2, PuO2, and ThO2 4.2.1 The uranium-oxygen system and UO2 4.2.2 The plutonium–oxygen system and PuO2 4.2.3 The thorium–oxygen system and ThO2 4.3 Binary and higher order oxide phase diagrams 4.3.1 UO2–PuO2 binary system 4.3.2 ThO2–UO2 binary system 4.3.3 ThO2–PuO2 binary system 4.3.4 Higher order system—diagrams of UO2–ThO2–PuO2 4.4 Doped fuels 4.5 Summary References 5 Other power reactor fuels 5.1 Introduction 5.2 Metallic fuels 5.2.1 Zirconium-based metallic fuels 5.2.1.1 Restructuring in U–Zr fuels 5.2.1.2 Fission product migration 5.2.2 Molybdenum-based metallic fuels 5.3 Nontraditional ceramic fuels 5.3.1 Carbide fuels 5.3.1.1 Binary phase diagram of U–C 5.3.1.2 Clad carburization 5.3.1.3 Incorporation of actinoids and fission products in uranium monocarbide 5.3.2 Nitride fuels 5.3.2.1 Binary phase diagram and relevant derivatives 5.3.2.2 Relevance of carbon and oxygen impurities to in-pile performance 5.3.2.3 Incorporation of actinoids and fission products in uranium mononitride 5.3.3 Other nontraditional ceramic fuel forms 5.3.3.1 Exploration of uranium silicide compounds for light-water reactor applications 5.3.3.2 Other fuel systems 5.4 Coated particle fuels 5.4.1 CO formation and the effect on particle integrity 5.4.1.1 Pressure vessel failure 5.4.1.2 Kernel migration 5.4.1.3 CO corrosion of SiC 5.4.1.4 Alternate tristructural isotropic fuels to address CO formation 5.4.2 Fission product chemistry and transport in tristructural isotropic fuel particles 5.4.2.1 Palladium 5.4.2.2 Silver 5.4.2.3 Fission gas 5.4.2.4 Cesium and iodine 5.4.2.5 Fission product transport in the reactor 5.4.3 Oxygen potential and fission products 5.5 Summary and outlook References Further reading 6 Molten salt reactor fuels 6.1 Introduction 6.1.1 Key advantages of the molten salt reactor 6.1.2 Challenges for molten salt reactor deployment 6.2 History of molten salt reactor research 6.3 Molten salt reactor renaissance 6.4 Molten salt reactor fuel concepts 6.5 Fuel salt properties 6.5.1 Melting point 6.5.2 Vapor pressure—boiling point 6.5.3 Heat capacity 6.5.4 Solubility of actinoids 6.5.5 Fission product retention 6.5.6 Stability to radiation 6.6 Measurements and experimental procedures 6.6.1 Handling 6.6.2 Sample synthesis and purification 6.6.3 High-temperature measurements—encapsulation 6.7 Redox potential of the fuel 6.7.1 Corrosion inhibition 6.7.2 Fission product speciation 6.7.3 Monitoring of redox potential during reactor operation 6.8 Effect of oxygen impurities 6.9 Effect of soluble fission product impurities 6.10 Conclusion References 7 Research reactor fuels 7.1 Introduction 7.2 Fuel geometry 7.2.1 Plate-type fuels 7.2.2 Tubular fuels 7.2.3 Rod- and pin-type fuels 7.3 Fuel materials 7.4 Evolution of research reactor fuel during operation 7.5 Fabrication processes 7.6 Fuel behavior under irradiation 7.6.1 Uranium aluminides 7.6.2 Uranium silicides 7.6.3 Uranium oxides 7.6.4 Uranium–molybdenum alloys 7.6.5 Uranium–zirconium hydride fuel 7.7 Corrosion of aluminum research reactor fuel cladding 7.8 Conclusion References C. Stages of the Fuel Cycle and Other Applications 8 Mining and milling 8.1 Introduction 8.2 Mining 8.2.1 Uranium resources 8.2.2 Uranium bearing minerals 8.2.3 Mining methods 8.2.3.1 Open pit mining 8.2.3.2 Underground mining 8.2.3.3 In situ leaching 8.3 Milling 8.3.1 Ion exchange 8.3.2 Solvent extraction 8.3.3 Precipitation 8.4 Tailings 8.5 Summary References 9 Uranium conversion and enrichment 9.1 Introduction 9.2 Natural uranium conversion processes 9.2.1 What is uranium conversion? 9.2.2 The special role of UF6 in the nuclear fuel cycle 9.2.3 Wet conversion processes for production of UF6 9.2.3.1 Dissolution 9.2.3.2 Solvent extraction 9.2.3.3 Concentration 9.2.3.4 Denitration (thermal and chemical) 9.2.3.5 Reduction 9.2.3.6 Hydrofluorination 9.2.3.7 Fluorination Direct fluorination of UF4 Fluorine production UF6 recovery 9.2.4 Dry fluoride volatility process for production of UF6 9.2.5 Production of ceramic-grade UO2 for pressurized heavy-water reactors 9.2.6 Production of uranium metal for Magnox reactors 9.3 Uranium enrichment 9.3.1 Uranium enrichment processes 9.3.1.1 Gas centrifuge enrichment process 9.3.1.2 Gaseous diffusion process 9.3.1.3 Laser isotope enrichment process 9.3.1.4 Electromagnetic enrichment process 9.3.1.5 Thermal diffusion process 9.3.1.6 Aerodynamic enrichment process 9.3.1.7 Chemical exchange process 9.3.2 Quality and transportation of enriched UF6 9.4 Conversion of enriched UF6 to UO2 9.4.1 Wet conversion processes 9.4.1.1 Ammonium diuranate route 9.4.1.2 Ammonium uranyl carbonate route 9.4.2 Dry conversion processes 9.4.2.1 Integrated dry route 9.4.2.2 Fluidized-bed conversion process 9.4.2.3 Fluidized bed—kiln conversion process 9.5 Conclusion and future trends References 10 Advances in fuel fabrication 10.1 Introduction 10.2 Ceramic fuel fabrication 10.2.1 Oxide fuel fabrication 10.2.1.1 Commercial oxide fuel production Wet chemical processing to produce UO2 Solid-state synthesis of UO2 Commercial powder metallurgy of UO2 10.2.1.2 Additives to UO2 10.2.1.3 Advanced fabrication of UO2 Sol–gel and hydrothermal routes for nanocrystalline UO2 synthesis Field-assisted sintering of UO2 Microwave sintering Additive manufacturing Powder injection molding UO2 10.2.2 Nitride fuel fabrication 10.2.2.1 Introduction to nitride fuel forms 10.2.2.2 UN synthesis and fabrication techniques Carbothermic reduction and nitridation Direct thermal (hydride–nitride) Alternative synthesis routes Nitride consolidation methods 10.2.3 Other ceramic fuel fabrication 10.2.3.1 Uranium borides 10.2.3.2 Uranium carbides 10.3 Metallic fuel fabrication 10.3.1 Introduction to metallic fuels 10.3.2 Fabrication methods for metallic fuels 10.3.2.1 Alloying and casting Arc melting Vacuum induction melting Microwave melting 10.3.2.2 Thermomechanical processing Rolling Coextrusion 10.3.2.3 Heat treatment 10.4 Advanced reactor fuel fabrication 10.4.1 High-density light-water reactor fuels 10.4.1.1 Uranium silicide pellet fabrication Compound synthesis Pellet fabrication Alloying additions to U–Si fuels 10.4.1.2 High-density composite fuels for light-water reactors 10.4.2 Coated particle fuel fabrication 10.4.2.1 Introduction to coated particle fuel 10.4.2.2 Tristructural isotropic fabrication 10.4.3 Molten-salt reactor fuel fabrication 10.4.3.1 Pyrochemical fuel salt synthesis 10.5 Conclusion Acknowledgments References 11 In-reactor behavior 11.1 Introduction 11.2 General description of fuel behavior 11.2.1 Thermal and fast reactor fuels 11.2.2 Radiation damage—irradiation effects 11.2.2.1 Temperature distribution 11.2.3 Microstructural evolution 11.2.4 Fuel swelling 11.3 Oxide fuel chemistry 11.3.1 UO2 and (U,Pu)O2 oxides 11.3.1.1 U–O and U–Pu–O phase diagrams 11.3.1.2 MOX fuel: effect of Pu 11.3.2 Irradiated oxide fuel 11.3.2.1 Chemical form of the fission products The gaseous fission products: He, Xe, Kr, I, Br, Rb, Cs The Cs uranate and molybdate phases Fission products dissolved in the matrix: (U,Pu,Sr,Y,Zr,Nb,La,Ce,Pr,Nd,Pm,Sm,Eu,Gd)O2±x Metallic precipitates: Mo, Tc, Ru, Rh, Pd Other Pd rich phases: (Pd,Ag,Te) and (Pd, Ag, Cd, In, Sn, and Sb phases), Te rich phases The gray phases (Ba,Sr,Cs)(U,Pu,Zr,Mo,RE)O3 Computational thermodynamics to predict the fission product phases in irradiated fuels 11.3.2.2 Oxygen chemical potential 11.3.2.3 Mass transport phenomena 11.3.2.4 Fuel–cladding chemical interaction 11.4 Other fuels chemistry 11.4.1 Irradiated fuel chemistry 11.4.2 Fuel–cladding chemical interaction 11.5 Conclusion—outlooks References 12 Reprocessing and recycling 12.1 Introduction 12.1.1 Characteristics of used nuclear fuel 12.1.2 Reuse of uranium from used light-water reactor fuel 12.1.2.1 Direct reuse in heavy-water reactors 12.1.2.2 Reenrichment option 12.1.2.3 Regenerated mixture 12.1.3 Zirconium recycle and disposition options 12.1.4 Hardware component recycle 12.1.5 Additional component recycle 12.2 Headend processing of Zircaloy-clad fuels for hydrometallurgical separations 12.2.1 Disassembly and decladding 12.2.1.1 Alternative mechanical-segmenting methods 12.2.1.2 Chemical decladding methods 12.2.1.3 Thionyl chloride–based chemical decladding 12.2.1.4 Hybrid decladding methods 12.2.2 Voloxidation 12.2.2.1 Early development 12.2.2.2 Coupled end-to-end demonstration at multikilogram scale with irradiated fuel 12.2.2.3 Recent advanced methods 12.2.3 Nitric acid dissolution 12.2.3.1 Traditional process 12.2.3.2 Dissolution following oxygen-based voloxidation 12.2.3.3 Dissolution following advanced voloxidation 12.2.4 Clarification and accounting 12.2.5 Disposition of cladding 12.2.5.1 Current industrial practice 12.2.5.2 Zirconium recovery for alternative dispositions 12.3 Headend processing for alternative or advanced fuels 12.3.1 TRISO fuels 12.3.2 The process of direct use of pressurized water reactor fuel in CANDU 12.3.3 Thorium-enhanced fuels 12.3.3.1 Thorex 12.4 Off-gas treatment and emission controls 12.4.1 Iodine 12.4.2 Tritium 12.4.2.1 Tritium released by voloxidation of fuel 12.4.2.2 Tritium released by cladding recycle 12.4.3 Carbon-14 12.4.4 Krypton 12.4.5 Noble metals and other semivolatiles 12.5 Separations 12.5.1 Hydrometallurgical separations—solvent extraction 12.5.2 Hybrid aqueous processing 12.5.3 Pyrochemical processes 12.5.4 Fluoride volatility 12.5.4.1 Introduction 12.5.4.2 Fluorinating agents 12.5.4.3 Separation methods 12.5.4.4 Coseparation of Pu, Np, and U from the bulk of UF6 12.5.4.5 Selective trapping of impurities using metallic fluorides Magnesium fluoride Sodium fluoride 12.5.5 Chloride volatility 12.5.5.1 Introduction 12.5.5.2 Processing of fuels 12.5.5.3 Chloride volatility in molten salts 12.5.5.4 Interconversion of chlorides and fluorides 12.5.5.5 Overall assessment of chloride volatility References 13 Spent nuclear fuel and disposal 13.1 Introduction—generalities on spent nuclear fuel 13.2 Spent nuclear fuel management strategies, closed versus open nuclear cycles 13.3 Spent nuclear fuel and high-level waste storage—international practices 13.3.1 Wet storage 13.3.2 Dry storage 13.3.2.1 Storage in casks/containers 13.3.2.2 Storage in silos 13.3.2.3 Storage in vaults 13.4 Spent nuclear fuel and high-level waste geological disposal—international practices 13.5 Key processes from operation to disposal through storage that impact the long-term stability of spent nuclear fuel 13.6 Dissolution and alteration of spent nuclear fuel under deep geological repository conditions 13.7 Outlook 13.8 Conclusion Appendix References Further reading 14 Advances in fuel chemistry during a severe accident 14.1 Introduction 14.2 Chemistry on fuel/core degradation 14.2.1 Chemistry in early phase fuel degradation 14.2.1.1 Oxidation and hydrogen uptake of Zry cladding 14.2.1.2 Liquefaction between UO2 fuel and Zry cladding 14.2.1.3 Liquefaction of control rod/blade and following interaction with Zry Silver–indium–cadmium control rod Boron carbide control rod or blade Reaction between B4C–stainless steel melt and Zry channel box 14.2.2 Chemistry in transition from early phase to late phase 14.2.3 Chemistry in late phase degradation 14.2.4 Chemistry on fuel degradation ex-vessel conditions 14.2.4.1 Phenomenology of molten core–concrete interaction 14.2.4.2 Interface interaction between molten core material and concrete 14.2.4.3 Phase/element distribution during solidification 14.2.4.4 Interaction with sea salt materials 14.3 Fission product chemistry at severe accident of light water reactors 14.3.1 Chemistry of fission product release from irradiated fuel during severe accident 14.3.1.1 Main issues addressed before Fukushima Daiichi accidents Basic process of fission product release from the fuel Release behavior of fission products that are sensitive to the oxidation-reduction conditions 14.3.1.2 Highlights from Fukushima Daiichi accidents (issues deserving further attention) Alteration of release behavior of non/low-volatile fission products by sea-water injection Boron release kinetics from degraded B4C control blades 14.3.2 Fission product chemistry in reactor coolant system, gas phase, and interactions with structure surface 14.3.2.1 Main issues addressed before Fukushima Daiichi accidents Cs–I–Mo–O–H chemistry during transport in the reactor coolant system Ru–N–O–H chemistry during transport in the reactor coolant system Remobilization of fission product deposits 14.3.2.2 Highlights from the Fukushima Daiichi accidents (issues deserving further attention) Chemical impact of boron on the Cs–I–Mo–O–H system Cs chemisorption phenomena Other issues 14.3.3 Fission product chemistry in containment, gas phase, and interactions with containment surfaces 14.3.3.1 Chemistry aspects affecting the formation of fission product aerosols in the containment and related potential rad... 14.3.3.2 Iodine and ruthenium chemistry in containment gas phase and how it may affect radioactive release 14.3.3.3 Focus on Org-I formation 14.3.3.4 Focus on iodine aerosol stability 14.3.3.5 Radioactive material transport and deposition in the containments in the three damaged units 14.3.3.6 Other aspects affecting physicochemical phenomena 14.3.3.7 Remobilization and transfer of radioactivity for long-term accidents 14.3.3.8 Mitigation of radioactive releases for long-term accidents—further development and qualification of filtered conta... 14.3.4 Chemistry in containment pools and in liquid scrubber containment venting systems 14.3.4.1 Main issues addressed and knowledge gained before the Fukushima Daiichi accidents 14.3.4.2 Highlights from the Fukushima Daiichi accidents—issues deserving further attention Pool scrubbing in suppression pools and scrubber filtered containment venting systems in relation to radioactive release mi... 14.3.4.3 Chemistry in coolant liquid phase on the long term 14.4 Conclusion References Index Back Cover