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Development of U 3 Si 2 Pellets for LWR Applications

Development of U 3 Si 2 Pellets for LWR Applications. Master Thesis. Anna Benarosch. Accident Tolerant Fuels (ATF). Fukushima (2011): UO 2 + Zircaloy New system: U 3 Si 2 + SiC or FeCrAl steel. Characteristics of ATF: High melting temperature Improved oxidation resistance

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Development of U 3 Si 2 Pellets for LWR Applications

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  1. Development of U3Si2 Pellets for LWR Applications Master Thesis Anna Benarosch

  2. Accident Tolerant Fuels (ATF) • Fukushima (2011): UO2 + Zircaloy • New system: U3Si2 + SiC or FeCrAl steel • Characteristics of ATF: • High melting temperature • Improved oxidation resistance • Increased thermal conductivity

  3. Approach • U3Si2 pellets fabrication • Doping with molybdenum (Mo) • Oxidation behavior in presence of H2O2

  4. U3Si2 Pellets Alloys: - Prepared by arc melting - 92.7 wt.% U + 7.3 wt.% Si Arc Melter Ingot of U3Si2

  5. U3Si2 Pellets Alloys: - Average: 101%TD - Presence of uranium inclusions - U3Si2 identified by XRD (1) (2)

  6. U3Si2 Pellets Pellets Fabrication: Alloys milled into powder in a glovebox Sintering of pellets by Spark Plasma Sintering Rate: 100°C/min Constant pressure of 124 bar U3Si2 pellet with a diameter of 1cm

  7. U3Si2 Pellets • SEM analysis: UO2 inclusions Pores Scratches • Oxygen level analysis:- 1500 ppm - 1.4 at.% of oxygen U3Si2 61300

  8. Doping with molybdenum (Mo) Why Mo? - Fission product - For a burn-up of 119,55 MWd/kg(U): 1.5 at.% of Mo - Other important contributions: Xe (1.9 at.%), Pu (2.7 at.%) Objectives: - Investigate the solubility/presence of a ternary phase

  9. Doping with molybdenum (Mo) Fabrication: - Milling of Mo in a glovebox - Mixing U3Si2 with Mo (1.5 at.%) - SPS at 1200°C for 6min (100°C/min) Different route in literature: - Different morphology - Far from burn-up structure U3Si2 U2Mo3Si4 U-rich eutectic matrix with dark U-rich constituents

  10. Doping with molybdenum (Mo) SEM: U2Mo3Si4 Mo U4Mo(MoxSi1-x)Si2 UO2

  11. Doping with molybdenum (Mo) U-rich phase U2Mo3Si4

  12. Oxidation behavior in presence of H2O2 Chemical stability in H2O2: - H2O2 present in irradiated water - Useful for repository considerations http://www.cea.fr/english/PublishingImages/Pages/fields-of-research/nuclear-energy/cea-research-on-the-current-nuclear-fleet/reactor-pool.jpg https://upload.wikimedia.org/wikipedia/commons/thumb/6/69/SKB_KBS-3.jpg/1200px-SKB_KBS-3.jpg

  13. Oxidation behavior in presence of H2O2 • Experiments: • - Investigation on 50mg powder in 25mL of H2O • - 0.2 mM of H2O2 • - 10 mM of NaHCO3 • - Aluminium covering • - N2 purging • Absorbance measurements using Ghormley method (H2O2) and Arsenazo III (U(VI))

  14. Oxidation behavior in presence of H2O2

  15. Conclusions • Production of U3Si2 pellets with a high density and an interesting microstructure through a new sintering route (SPS) • Similar methodology relevant for the study of the interaction of fission products with the matrix • Understanding the reactivity of U3Si2 towards H2O2 • Future work: • Experiments in presence of gamma radiation source • Comparison with UO2 • Following the reaction by ICP-OES • Similar experiment on a U3Si2 pellet

  16. References • J. Bischoff, P. Blanpain, J-C. Brachet, C. Lorette, A. Ambard, J. Strumpell, K. McKoy, Developpment of fuels with enhanced accident tolerance, IAEA-TECDOC-1797 (2014), 22-29 • J. M. Harp, P. A. Lessing, R. E. Hoggan, Uranium silicide pellet fabrication by powder metallurgy for accident tolerant fuel evaluation and irradiation, J. of Nucl. Mat., 466 (2015) 728-738 • S.B. Ross, M. S. El-Genk, Thermal conductivity correlation for uranium nitride fuel between 10 and 1923K, J. of Nucl. Mat. 151 (1988) 318-326 • S.C. Middlebrugh, R.W. Grimes, E.J. Lahoda, C.R. Stanek, D.A. Andersson, Non-stoichiometry in U3Si2, J. of Nucl. Mat. (2016) • Z. Zang, Z. Liu, J. Lu, X. Shen, F. Wang, Y. Wang, The sintering mechanism in spark plasma sintering – Proof of the occurrence of spark discharge, ScriptaMateriala 81(2014) 56-59 • N. Saheb, Z. Iqbal, A. Khalil, A.S. Hakeem, N. Al Aqeeli, T. Laoui, A. Al-Qutub, R. Kirchner, Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites: A Review, J. of Nanomaterials (2012) 1-13 • P. Rogl, T. Le Bihan, H. Noël, Phase equilibria and magnetisme in the Mo-Si-U system, J. of Nucl. Mat., 288, (2001) 66-75 • P. A. Lesing, Oxidation Protection of Uranium Nitride Fuel Using Liquid Phase Sintering, Idaho National Laboratory 2012 • S. Wetzel, M. Klevenz, H.-P. Gail, A. Pucci, M. Trieloff, Laboratory measurement of optical constants of solid SiO and application to circumstellar dust, A&A 553, A92 (2013) • E. Sooby Wood, J.T. White, A.T. Nelson, Oxidation behavior of U-Si compounds in air from 25 to 1000C, J. of Nucl. Mat. 484 (2017) 245-257 • K. Schulmeister, W. Mader, TEM investigation on the structure of amorphous silicon monoxide, J. of Non-Crystalline Solids 320 (2003) 143-150 • E. R. Lippincott, A. Van Valkenburg, C. E. Weir, E. N. Bunting, Infrared studies on polymorphs of silicon dioxide and germanium dioxide, J. of Research of the National Bureau of Standards 61 (1958) 61-70 • D. Swiatla-Wojcik, Hybrid method for numerical modelling of LWR coolant chemistry, Radiation Physics and Chemistry, 127 (2016) 236-242 • A. B. Fidalgo, M. Jonsson, Can H2 enhance the oxidative dissolution of UO2?, J. Nucl. Mat. 477 (2016) 85-87

  17. Thank you for your attention! • Time for questions

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