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NERI PROJECT REVIEW

NERI PROJECT REVIEW. NERI 08-041 Performance of Actinide-Containing Fuel Matrices Under Extreme Radiation and Temperature Environments University of Illinois Brent J. Heuser Panel No. 1 Session 7. Project Objectives.

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NERI PROJECT REVIEW

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  1. NERI PROJECT REVIEW NERI 08-041 Performance of Actinide-Containing Fuel Matrices Under Extreme Radiation and Temperature Environments University of Illinois Brent J. Heuser Panel No. 1 Session 7

  2. Project Objectives • Establish UO2 thin film growth capability with controlled microstructure, stoichiometry, and actinide surrogate concentrations. • Determine transport properties of actinide surrogates and implanted volatile fission gases under conditions that mimic the fission process in nuclear reactors. • Investigate affect of microstructure, stoichiometry, and impurity concentration of transport properties. • Develop and apply predictive computational models of transport mechanisms at an atomistic level. NERI PROJECT NO. 08-041

  3. Project Work Scope • Task 1—construction of dedicated UO2 thin film growth facility; grow CeO2 surrogate films in the interim. • Task 2—perform transport studies of actinide surrogate and fission gases. • Task 3—develop computational tools for predictive modeling. • Task 4—apply computational models to actinide/fission gas transport. NERI PROJECT NO. 08-041

  4. Project Participants • Lead Organization: University of Illinois • PI: Brent J. Heuser • CoPIs: J. Stubbins, R. Averback. P. Bellon, J. Eckstein • Collaborating Organizations: • Georgia Institute of Technology/CoPIs: C. Deo, M. Li • University of Michigan/CoPI: L. Wang • South Carolina State University/CoPI: M. Danjaji NERI PROJECT NO. 08-041

  5. Organizational Roles • University of Illinois • Provide thin film samples; study transport phenomena; develop computational tools for predictive transport studies based on MC, MD, kMC. • Georgia Institute of Technology • Perform first-principles and kMC computations of transport phenomena; develop digital microstructure. • University of Michigan • Perform in situ studies of actinide/fission gas transport. • South Carolina State University • Participate in experimental studies performed at Illinois via student/faculty exchange. NERI PROJECT NO. 08-041

  6. Task 1 (Film Growth) Progress • Design and construction of dedicated thin film growth facility at Illinois complete. • Commissioning of facility underway. • MBE capability for CeO2 surrogate thin films with actinide surrogates established. NERI PROJECT NO. 08-041

  7. Crystal Structure Fluorite Structure—anions red, cations white CeO2 Tm=2673 K a=5.4114 A UO2 Tm=3138 K a=5.466 A NERI PROJECT NO. 08-041

  8. Molecular Beam Epitaxy R-plane sapphire + CeO2 or UO2 Lattice mismatch: CeO2 <2% UO2 <1% NERI PROJECT NO. 08-041

  9. XRD Analysis of MBE CeO2 film NERI PROJECT NO. 08-041

  10. Ar2 Air Ar1 O2 Sputter Deposition Facility Schematic Foreline pump MFC1 MFC2 FV1 VV1 FV2 SV4 SV6 TP1 PG TCG Mass Spec. GV1 APC RV CG1 CM2 TP2 VV2 IG1 CM1 GV2 Sample Trans. Arm CM3 Primary Chamber Load- lock Thickness Monitor CG2 IG2 SV5 CG—convectron gauge IG—ion gauge TCG—thermocouple gauge PG—Pirani gauge CM—capacitance manometer MFC—mass flow controller S—sputter gun TP—turbo pump GV—gate valve FV—foreline valve VV—vent valve SV—solenoid valve RV—relief valve S1 S2 S3 SV2 SV1 SV3

  11. Magnetron Sputtering System at Illinois Targets: depleted U; Ce; Nd Power Supply: 2 DC; 1 RF Gas Supply: O2: 0 to 10 sccm Ar: 1 to 100 sccm Max. Ts=850 C NERI PROJECT NO. 08-041

  12. MBE vs. Reactive Gas Sputtering (RGS)Comparison of SIMS Positive Ion Collection MBE—2302 RGS—3 NERI PROJECT NO. 08-041

  13. Berg Model for Reactive Gas Sputtering Thin Solid Films, 476 (2005) 215 metal mode poison mode NERI PROJECT NO. 08-041

  14. Poison vs. Metal Modes in Reactive Gas Sputtering NERI PROJECT NO. 08-041

  15. Poison vs. Metal Sputtering Modes NERI PROJECT NO. 08-041

  16. XRD Analysis of Sputtered CeO2 film NERI PROJECT NO. 08-041

  17. Control of RGS Film Microstructure NERI PROJECT NO. 08-041

  18. Task 1 Planned Activities • Thin film growth facility finished—currently growing CeO2 films for benchmarking, commissioning. • UO2 films in the next few months. • UO2 films with controlled microstructure, actinide surrogate concentration, stoichiometry. • CeO2 films via MBE with actinide surrogates to continue. • Additional implantation of UO2 and CeO2 films w/Xe. NERI PROJECT NO. 08-041

  19. Task 1 Issues or Concerns • Shutter design of source flange somewhat problematic and may require periodic (~quarterly) adjustment. • Debris build up will require the system to be opened occasionally (~quarterly). • Do not control MBE system—can expect 1 to 4 samples per month. NERI PROJECT NO. 08-041

  20. Task 2 (Experimental Transport Studies) Progress • Performed RED measurements of cation sublattice in CeO2 with a La marker layer. • Performed low-energy Xe implantations in CeO2 at two concentrations for fission gas bubble dissolution experiments. • Irradiated Xe-implanted CeO2 samples with Kr. • Developed TEM specimen preparation techniques. • Performed ex situ TEM analysis of irradiated CeO2 and Xe-implanted CeO2. • Performed in situ TEM analysis of Xe-implanted CeO2. • Performed EXAFS measurements of Xe implanted (unirradiated) CeO2. NERI PROJECT NO. 08-041

  21. Experimental Facilities at Illinois • Microanalytical: AES, SIMS, RBS, XRD/XRR, TEM, SEM, AFM. • Implantation: tandem van de Graaff (0.5-2.3 MeV; H, He, Xe, Kr, Ne; ~100 nA) NERI PROJECT NO. 08-041

  22. SIMS of Irradiated Single Crystal CeO2 360 A thickness w/1 ML La at centerline 1.8 MeV Kr; 1 ion/A2 at RT NERI PROJECT NO. 08-041

  23. La Depth ProfilesRT Irradiation 1.8 MeV Kr NERI PROJECT NO. 08-041

  24. Mixing Parameter Analysis in CeO2 at RT1.8 MeV Kr x=6 A5/eV NERI PROJECT NO. 08-041

  25. Radiation-Enhanced Diffusion in CeO21.8 MeV Kr at dose of 1 ion/Å2 Dth=2.64x10-16 exp(-0.154 eV/kT) [cm2/sec] DRED=5.25x10-16 exp(-0.091 eV/kT) [cm2/sec] NERI PROJECT NO. 08-041

  26. Task 2 Planned Activities • RED investigation of anion sublattice with O-18 in CeO2 and UO2. • Further RED investigations on cation sublattice in UO2 and CeO2. • Implementation of model based on kinetic rate equations for RED. • EXAFS, SAXS, SIMS studies of precipitation of actinide surrogates and Xe. • Further in situ and ex situ TEM analysis of actinide surrogate precipitation and Xe bubble formation/dissolution. NERI PROJECT NO. 08-041

  27. Task 2 Issues or Concerns • Availability of ANL in situ TEM facility—Saclay facility available for use via P. Bellon. • Supply of samples to L. Wang (U. Mich) delayed—Xe implanted samples, other samples within next month. NERI PROJECT NO. 08-041

  28. Task 3/4 (Development/Application of Computational Tools for Predictive Modeling) Progress • Development of combined MC-MD approach to model UO2 at Illinois complete. • Study of Xe bubble homogeneous re-solution in UO2 via MC-MD complete. • Study of Xe bubble heterogeneous re-solution in UO2 via MD complete. • Development of DFT-kMC capability for UO2 at Georgia Institute of Technology complete. • Initial studies of oxygen transport in UO2 using DFT-kMC complete. • Development of geometric computational methods for polycrystalline media based on constrained Voronoi tessellation (digital microstructure) complete. NERI PROJECT NO. 08-041

  29. Computational Method Develop w/DFT Interatomic Interaction Potential Existing Molecular Dynamics DFT Em short time scales [ps] displacement cascades rate catalog kMC long time scales diffusive motion NERI PROJECT NO. 08-041

  30. MC-MD Study of Homogeneous Xe Bubble Re-solution in UO2 Xe recoil spectrum from MC. Homogeneous re-solution: Interaction of fission fragment with fission gas atoms in bubble via energetic collisions (ballistic ejection). Heterogeneous re-solutions: Interaction of displacement cascade with entire bubble. Schwen et al., J. Nuclear Materials, 392 (2009) 35. NERI PROJECT NO. 08-041

  31. MC-MD Study of Homogeneous Xe Bubble Re-solution in UO2 Computational Details MC: BCM, ZBL potential, based TRIM algorithm to treat arbitrary geometries and irradiation conditions (not fixed layer geo.). MD: LAMMPS code Long range Coulomb U-O treated PPPM method. Rigid-ion potential; U-U U-O O-O all Morelon potential in UO2 plus U-O Born-Mayer-Huggins covalent bonding O-O Born-Mayer + polynomial + 1/r6 U-U pure Coulombic NERI PROJECT NO. 08-041

  32. MC-MD Study of Homogeneous Xe Bubble Re-solution in UO2 Histogram of displacement lengths of Xe atoms from bubble center. Probability of Xe atoms leaving Bubble vs. Xe PKA energy. Re-solution parameter: 3x10-6 s-1 Xe knock-outs per Xe gas atoms This result is factor of 50 lower than analytical work of Nelson. NERI PROJECT NO. 08-041

  33. Channeling Xe atom displacement histograms MC+MD MC NERI PROJECT NO. 08-041

  34. MD Simulations of Heterogeneous Xe Bubble Re-solution in UO2 13 11 Two temperature model coupling electronic and phonon (atom) contributions based on sputtering yield benchmarks. dE/dx=55.4 keV/nm 6 2 Conclusions No Xe re-solution dE/dx<34 keV/nm (ff: 18-22 keV/nm) ff cross section for interaction w/bubble ~5 nm2 1-5 ff-bubble interactions per ff complete bubble destruction never observed dE/dx=47.0 keV/nm dE/dx=32.8 keV/nm 79 Xe atoms 0 Huang et al., to be submitted 9/2009 NERI PROJECT NO. 08-041

  35. DFT-kMC Simulations of Oxygen Diffusion in UO2+x Buckingham Potential for UO2 DFT LDA+U for UO2 di-interstitial mechanism NERI PROJECT NO. 08-041

  36. Task 3 Planned Activities • Further MC-MD studies of Xe bubble behavior; coupling of computational studies to experimental investigations (EXAFS, SAXS, in situ TEM) of bubble behavior in UO2. • Further DFT and kMC studies of transport phenomena in UO2; coupling of computational studies to experimental investigations (RED) of transport behavior in UO2. • Application of geometric methods of microstructure to polycrystalline UO2 in MC and MD; coupling of MC polycrystalline models to RED in polycrystalline UO2. NERI PROJECT NO. 08-041

  37. Task 3 Issues or Concerns • None. NERI PROJECT NO. 08-041

  38. Project Milestones Schedule Note 1: Enter ‘C’ if milestone has been completed; ‘O’ if milestone is on schedule for completion; or, ‘B’ if milestone is behind schedule for completion. NERI PROJECT NO. 08-041

  39. Year 1 Planned Vs. Actual Costs NERI PROJECT NO. 08-041

  40. Year 2 Planned Vs. Actual Costs NERI PROJECT NO. 08-041

  41. Year 3 Planned Vs. Anticipated Costs NERI PROJECT NO. 08-041

  42. Project Accomplishments—To Date • Dedicated thin film growth facility completed. • Commissioning nearly completed. • Control of microstructure (via Ts), stoichiometry (via O2 pressure) and actinide concentration (via gun power level) demonstrated. • RED on cation sublattice in CeO2 measured up to 1208 K. • Initial in situ TEM analysis of Xe bubble resolution in CeO2 performed. • Initial EXAFS measurements of Xe bubble resolution in CeO2 performed. • Computational tools in place; initial set of studies (Xe bubble resolution, oxygen diffusion, microstructure modeling via inverse MC) complete. NERI PROJECT NO. 08-041

  43. Project Accomplishments—Anticipated • Demonstrate of UO2 thin film growth with controlled stoichiometry, microstructure, actinide surrogate concentration. • RED measurements on cation and anion sublattices in UO2 under different bombardment conditions (T, dose, E). • Measurements of Xe and actinide surrogate precipitation behavior in UO2 under different bombardment conditions. • Determination of synergistic effect of UO2 microstructure, bombardment conditions, impurity concentrations. • Further kMC and MD simulations of transport behavior. NERI PROJECT NO. 08-041

  44. R&D Programs Benefits • Project addresses the nuclear fuel cycle by investigating materials aspects of actinide incorporation into UO2 matrices. • Project will provide: • Measurements of actinide and fission gas transport properties in UO2. • Computational tools for predictive modeling of transport properties. • Successful completion of this project will facilitate an improved understanding of fuel behavior within a closed fuel cycle. NERI PROJECT NO. 08-041

  45. Programmatic Contributions • Contribution to NERI Program objectives: • Project helps close the fuel cycle by providing data and predictive modeling capabilities that promote better understanding of UO2 containing actinides. • Project will advance the state of nuclear technology in the U.S. by 1) aiding in the reduction of waste disposition time scales and 2) increasing fuel efficiency via recovery of major actinide energy content. • Project addresses nuclear science and engineering infrastructure through the training of young researches: Illinois: 4 UG, 8 Grad, 2 post-doct. Georgia: 5 Grad Michigan: 1 Grad, 1 post-doct. And the development of capabilities at Illinois and Georgia Tech. NERI PROJECT NO. 08-041

  46. Commercialization Potential • Potential exists through Hitachi GE Nuclear. NERI PROJECT NO. 08-041

  47. Potential Future R&D Efforts • A dedicated UO2 thin film growth facility at Illinois represents a unique capability; we anticipate studies beyond the current NERI grant within the AFCI. • Development of computational tools at Illinois and Georgia Institute of Technology offers potential for further synergistic efforts of collaboration between the two institutions within the AFCI. NERI PROJECT NO. 08-041

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