Basic Research Needs for Advanced Nuclear Energy Systems

1. US Private 3% Foreign 14% US Lab 38% Fed 23% US Univ 22% Basic Research Needs for Advanced Nuclear Energy Systems July 31–August 2, 2006 Workshop Co-chairs Panels: Materials under extreme conditions Chemistry under extreme conditions Separations science Advanced actinide fuels Advanced waste forms Predictive modeling and simulation Crosscutting and grand-challenge science themes Plenary Speakers: David Hill, Tom Mulford, Sue Ion, Vic Reis Steve Zinkle, Carol Burns, Thom Dunning Tomas Diaz de la Rubia JimRoberto Workshop Charge To identify basic research needs and opportunities in advanced nuclear energy systems and related areas, with a focus on new, emerging and scientifically challenging areas that have the potential to have significant impact in science and technologies. Highlighted areas will include improved and new materials and relevant chemical processes to overcome short-term showstoppers and long-term grand challenges for the effective utilization of nuclear energy. 235 attendeesexpected

2. Workshop Process • "Technology Perspectives" document distributed to all panelists one month in advance of the workshop • Plenary session on DOE technology perspective, industrial perspective, international perspective, and science frontiers • Breakout panels with technology resources • Technology challenges • Current status of research • Basic research challenges, opportunities, and needs • Priority research directions • Science/technology relationships • Plenary presentations by breakout panels at workshop midpoint and closing • Full workshop report in the next 8 weeks

3. Advanced Nuclear Energy Systems technology challenges • Predictive modeling of the design and performance of advanced nuclear energy systems, including fuel cycle modeling, reactor systems, chemical separation and conversion technologies for fuel fabrication and reprocessing, and waste form lifetime prediction • Radically improve the fundamental basis for developing and predicting the behavior of advanced fuel and waste forms, thus leading to outstanding fuel performance and the design of safer and more efficient nuclear energy systems • Fuel fabrication and performance prediction have been treated as an empirical endeavor. Development of theory guided methodology is needed for a cost effective and less time consuming path to development of fuels with tailored properties. • Advanced structural materials are required that can withstand higher temperatures, higher radiation fields, and harsher chemical environments. • Flexible and optimized separation and reprocessing schemes that will accommodate varying radiation fields generated from waste streams and input feeds are required

4. Advanced Nuclear Energy Systems technology challenges (cont.) • Predictive modeling of mechanical, thermal, and chemical properties of nuclear fuels, structural materials, and waste-form materials in high-radiation, high-temperature, and harsh chemical environment. • Avoiding separated plutonium and achieving improved yield and separation factors in PUREX and UREX+ processes (reducing stages, reducing footprints) • New and novel waste-form materials tailored a wide range of waste stream compositions from advanced fuel cycle technologies (e.g., reduced actinides and increased fission product concentrations). • Long-term prediction of waste form performance (e.g., corrosion rates and radiation effects) in coupled, complex, natural systems. • Proliferation resistance through physical protection and material accountability with improved precision in materials accountability for industrial-scale separations plants, including sampling methods and detectors

5. Current Status of Materials and Chemical Research for Advanced Nuclear Energy Systems • Most models are semi-empirical with little predictive capability • Limited understanding of microstructural evolution, kinetics, thermodynamics, and chemistry under extreme conditions • Theory and simulation inadequate to address complex, multi-component systems • Limited data on transuranic incorporation and properties • Limited capability to connect chemical and physical properties to nanoscale • Failure and corrosion mechanisms in chemical and radiation environments poorly understood • Limited understanding of radiolysis and radiation chemistry in separations • Current electronic structure methods fail for actinide materials • No robust way to link single-scale methods into a multi-scale simulation, or to perform long-time dynamics calculations

6. Basic Research Challenges, Opportunities, and Needs Understand and control chemical and physical phenomena in multi-component systems from femtoseconds to millennia, at temperatures to 1000°C, and radiation doses to hundreds of dpa • Microstructural evolution and phase stability • Mass transport, chemistry, and structural evolution at interfaces • Chemical behavior in actinide and fission-product solutes • Solution phenomena • Nuclear, chemical, and thermomechanical phenomena in fuels and waste forms • First-principles theory for f-electron complexes and materials • Predictive capability across length and time scales • Material failure mechanisms

7. Advanced actinide fuels: Basic-science challenges, opportunities, and needs The greatest science challenge is to understand and predict the broad range of nuclear, chemical, and thermo-mechanical phenomena that synergistically interact to dictate fuel behavior. The greatest scienceopportunity lies in establishing a science base that enables us to move away from lengthy and costly empirical approaches to fuel development and qualification. The greatest scienceneed is a revolutionary advance in our ability to conduct science-driven experiments to promote an integrated understanding of nuclear materials and their behavior.

8. Advanced actinide fuels: Develop a fundamental understanding of actinide-bearing materials properties Scientific challenges Summary of research direction Mystery of 5f-electron elements New paradigm for 5f-electron research • Overcome limitations in current experimental/theoretical approaches to determining/describing actinide material properties • Fundamental understanding of thermal properties of complex microstructure/composition materials • New approach to modeling phase stability/compatibility in complex, multicomponent actinide systems • Develop new quantum chemical/molecular dynamic approaches that can accommodate the additional complexity of 5f elements • Utilize/develop non-conventional experimental techniques to measure and model thermal properties of complex behavior actinide materials • Develop innovative defect models for multi-component actinide fuel/fission product systems Potential scientific impact Potential impact on ANES Breaking the code of fuel properties Beyond cook and look • Understanding/modeling thermal properties of complex materials • Unique phase equilibria of 5f systems • Innovative theoretical approaches for 5f systems • Novel experimental thermochemical techniques • Scientific basis for nuclear fuel design • Optimizing fuel development and testing • Reducing uncertainty in operational/safety margins

9. Advanced actinide fuels Relationships between the Science and the Technology Offices in DOE Applied Research Technology Maturation & Deployment Discovery Research Use-inspired Basic Research Office of Science: BES Applied Energy Office: NE • New methods for electronic structure calculations in actinides • Integration of computational models: atomistic to continuum • Develop fundamental understanding of actinide-bearing material properties • Understand fundamental reaction mechanisms that control transport, and consolidation of atomic species in complex multi-component systems • Innovative experimental methods for dynamic, in situ measurements of fundamental properties • Understand and predict microstructural and chemical evolution in actinide fuel during irradiation • Revolutionary synthesis approaches and architectures for advanced fuel forms • Bench-scale and laboratory-scale sample fabrication and characterization • Out-of-pile testing for phenomenological understanding • Relevant irradiations, and post-irradiation examination of samples • Transient irradiations to study failure mechanisms and thresholds • Establishment of experimental database and predictive correlations • Develop fuel performance code • Demonstration of the scaling to production-scale by process prototyping • Process control, efficiency and cost • Maintenance • Quality assurance • Development and validation of fuel licensing code for design and safety basis • Fabrication and characterization of lead test assemblies • Irradiation of lead test assemblies (LTAs) in prototypic environment

10. Priority Research Directions 1 (draft) • Microstructural evolution under extreme conditions of radiation, temperature, and aggressive environments • Properties of actinide-bearing materials, including solution- and solid-state chemistry and condensed matter physics of f-electron systems • Materials and interfaces that radically extend performance limits for structural applications, fuels, and waste forms • Effects of radiation and radiolysis in chemical processes and separations

11. Priority Research Directions 2 (draft) • Mastering actinide and fission-product chemistry, organization at multiple length scales, and non-aqueous and other novel approaches for next-generation separations • Chemistry of liquid-solid interfaces under extreme conditions • Behavior of trace species in radiation environments • Thermodynamic and kinetics of multi-component systems • Predictive multi-scale models for materials and chemical phenomena in multicomponent systems under extreme conditions

12. Overarching Themes • Strongly coupled, multi-scale experimental and computational studies • Nanoscale structure/dynamic and ultrafast experiments under realistic conditions • New approaches for enabling access to forefront tools for research on radioactive materials • An urgent need for assessment of workforce issues in nuclear-related research • Recognition of safety and nonproliferation opportunities

13. Relationships between the Science and the Technology Offices in DOE (draft) Applied Research Technology Maturation & Deployment Discovery Research Use-inspired Basic Research Office of Science: BES Applied Energy Office: NE • Rational design and development of reactor fuels • Verified and validated modules for reactor-level multi-scale simulations • Develop 3D fuel performance code • Laboratory-scale sample fabrication and characterization with relevant post-irradiation examination of samples • Demonstrating new separation systems at bench scale • At-scale demonstration of waste form performance in deep geologic laboratory • Accurate relativistic electronic structure approaches for correlated f-electron systems • Integration of multi-physics, multi-scale computational models: atomistic to continuum • Reactivity, dynamics, molecular speciation and kinetic mechanisms at interfaces • Utilize microstructure control to impart radiation resistance to structural materials for ANES • Innovative experimental methods for dynamic, in situ measurements of fundamental properties • Predict microstructural and chemical evolution in actinide fuel, cladding and structural materials during irradiation • Identify self-protective interfacial reaction mechanisms capable of providing universal stability in extreme environments • Improve understanding of coordination geometry, covalency, oxidation state, and cooperative effects of actinides to devise next generation separation methods. • Predict the behavior of waste forms over millennia • Demonstration of the scaling to production-scale by process prototyping • Development and validation of fuel licensing code for design and safety basis • Fabrication and characterization of lead test assemblies • Irradiation of lead test assemblies (LTAs) in prototypic environment • Coupling waste form performance to design and performance of a repository.