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Russian Federal Nuclear Centre – Institute of Technical Physics

MODELING OF PLUTONIUM AGEING. Russian Federal Nuclear Centre – Institute of Technical Physics. VLADIMIR DREMOV Russian Federal Nuclear Centre – Institute of Technical Physics , Snezhinsk , Russia, E-mail: V.V.Dryomov@vniitf.ru. COLLABORATORS.

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Russian Federal Nuclear Centre – Institute of Technical Physics

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  1. MODELING OF PLUTONIUM AGEING Russian Federal Nuclear Centre – Institute of Technical Physics VLADIMIR DREMOV Russian Federal Nuclear Centre – Institute of Technical Physics, Snezhinsk, Russia,E-mail:V.V.Dryomov@vniitf.ru

  2. COLLABORATORS Russian Federal Nuclear Centre – Institute of Technical Physics, Snezhinsk, Russia, ALEXEY KARAVAEV, SERGEY SAMARIN, FILIPP SAPOZHNIKOV, GENNADY IONOV Institute of Metal Physics, Russsian Academy of Sciences – Ural Division, Yekaterinburg, Russia MICHAEL KOROTIN, ALEXEY SHORIKOV, DMITRY KOROTIN, VLADIMIR ANISIMOV Los Alamos National Laboratory, Los Alamos, NM MARVIN ZOCHER, DEAN PRESTON Lawrence Livermore National Laboratory, Livermore, CA BRANDON CHUNG Russian Federal Nuclear Centre – Institute of Technical Physics

  3. Introduction • That is why the atomistic approach tomaterial properties modeling is one of the rapidly developingdirections of the theoretical material science. • This approachgives detailed information on the structures and processes on themicro-level and provides us with information on mechanical and thermodynamic properties of materials. • For Plutonium and its alloys the Modified Embedded Atom Model is widely used to describe interatomic interaction within Molecular Dynamics approach. • Despite of a number of shortcomings presently MEAM is the only model that is capable to reproduce a variety of PuGa properties in the frame of classical MD approach Russian Federal Nuclear Centre – Institute of Technical Physics

  4. * * Lattice constant and density of fcc Pu-Ga alloys *taken from Los Alamos Science, #26, volume II, 2000. MEAM Parameters (M. I. Baskes, A. C. Lawson, S. M. Valone, Phys. Rev. B, v. 72 (2005), p. 014129) Russian Federal Nuclear Centre – Institute of Technical Physics

  5. Elastic moduli of fcc Pu-Ga alloys * A. Migliori et al., J Alloys and Comp, 444-445, 197-201, (2007). ** C.A. Calder, E.C. Draney, W.W. Wilcox,, J. Nucl. Mater. 97 (1981) pp. 126-136. *** H. M. Ledbetter and R.L. Moment, Acta Metall. 24 (1975) 891. Russian Federal Nuclear Centre – Institute of Technical Physics

  6. Thermal expansion and heat capacity * J. M. Taylor, Thermal Expansion of Some Plutonium-Gallium Solid Solution Alloys, J. Nucl. Mater. 31 (1969) pp. 339-341. 1. R. O. Adams, F. L. Oetting, J. Nucl. Mater. 118 (1983) pp. 269-274. 2. R. L. Rose, J. L. Robbins, T. B. Massalski, J. Nucl. Mater. 36 (1970) pp. 99-107. 3. J. C. Taylor, P. F. Linford, D. J. Dean, J. Inst. Met. 9 (1965) p. 178. 4. J. C. Taylor, R. G. Loasby, D. J. Dean, P. F. Linford, In Plutonium 1965 (C&H, London,1967) p. 162. 5. J. C. Lashley et all., Phys. Rev. Let. v. 91, n. 20 (2003) p. 205901. Russian Federal Nuclear Centre – Institute of Technical Physics

  7. MD Simulation of Ageing • The ageing of Pu, i.e., the change of its properties with time due to self-irradiation, is caused by the accumulation of radiation defects and helium in the bulk of the material. Investigation into this complicated problem may be addressed to Molecular Dynamics (MD). • The radioactive decay of Pu generates high-energy particles of U (86 keV) and He (5 MeV) producing numerous damages when decelerating in the bulk of the material. • Recent MD investigations into plutonium self irradiation effects [1-3] revealed main features of this phenomenon. • V.V.Dremov, F.A. Sapozhnikov, S.I. Samarin, D.G. Modestov, N.E. Chizhkova, Journal of Alloys and Compounds, v. 444-445, pp.197-201, (2007). • L. Berlu, G. Jomard, G. Rosa, P. Faure, Journal of Nuclear Materials, V.374, pp 344-353,(2008). • W. G. Wolfer, A.Kubota, P. Söderlind, A. I. Landa, B. Oudot, B. Sadigh, J. B. Sturgeon, M. P. Surh, Journal of Alloys and Compounds, v. 444-445, pp.72-79, (2007). Russian Federal Nuclear Centre – Institute of Technical Physics

  8. t=0.3 ps Atomistic modeling of the primary displacement damage in Pu-Ga alloys* *V.V.Dremov, F.A. Sapozhnikov, S.I. Samarin, D.G. Modestov, N.E. Chizhkova, Journal of Alloys and Compounds, v. 444-445, pp.197-201, (2007). Russian Federal Nuclear Centre – Institute of Technical Physics

  9. Atomistic Characterization of Defect Mobilities Temperature dependence of defect mobilities was evaluated through straightforward MD simulations Defect types: self-interstitials, vacancies, di-vacancies, tri-vacancies. • The data for vacancies and di-vacancies were obtained in [4]. • The data for self-interstitials were obtained in [5]. • The data for tri-vacancies were obtained in [7]. In all MD calculations the Modified Embedded AtomModel by Baskes [6] was used to describe interatomic interaction. • Results of MD calculations were approximated by Arrhenius law by fitting • Ratepre-factor and Activation energy W • 4. B.P. Uberuaga, S.M. Valone, M.I. Baskes, Journal of Alloys and Compounds, v. 444-445, pp.314-319, (2007). • 5. V.V. Dremov, A.L. Kutepov, Ph.A. Sapozhnikov, D.L. Preston, M.A. Zocher, Phys. Rev. B., 77, 224306, (2008). • 6 .M.I. Baskes, A.C. Lowson, S.M. Valone, Phys. Rev. B, 72 (2005) 014129. • 7. V.V. Dremov, A.V. Karavaev, Ph.A. Sapozhnikov, D.L. Preston, M.A. Zocher, J. Nucl. Mater., 385 (2009), 79-82. Russian Federal Nuclear Centre – Institute of Technical Physics

  10. Quantitative Characterization of Defects Dremov et al. Valone et al. Valone et al. Dremov et al. Valone et al. Dremov et al. Russian Federal Nuclear Centre – Institute of Technical Physics

  11. Primary radiation defect accumulation model Evolution of the defect system with time is described by the following equations: Russian Federal Nuclear Centre – Institute of Technical Physics

  12. Evolution of the defect system at T=300K and average grain size 20m Solid lines – Wv=1.06eV, Dashed lines – Wv=1.06eV Russian Federal Nuclear Centre – Institute of Technical Physics

  13. Evolution of vacancy concentration Defect system includes: 1 - I + V 2 - I + V + 2V 3 - I + V + 2V + 3V Russian Federal Nuclear Centre – Institute of Technical Physics

  14. Accumulation of defects and volume change Markers – data from [7], Dashed line – this work 7. B.W. Chung, S.R. Thompson, C.H. Woods, D.J. Hopkins, W.H. Gourdin, B.B.Ebbinghaus, Density changes in plutonium observed from accelerated aging usingPu-238 enrichment. Journal of Nuclear Materials, V.355, P.142-149, (2006). Russian Federal Nuclear Centre – Institute of Technical Physics

  15. Effect of defects on thermodynamic and mechanical properties *A. Migliori et al., Temperature and time-dependence of the elastic moduli of Pu and Pu-Ga alloys, J. Alloy and Compound, in press. **H. M. Ledbetter and R.L. Moment, Acta Metall. 24 (1975) 891. ***C.A. Calder, E.C. Draney, W.W. Wilcox. Noncontact Measurement of the Elastic Constants of Plutonium at Elevated Temperatures, J. Nucl. Mater. 97 (1981) pp. 126-136. Russian Federal Nuclear Centre – Institute of Technical Physics

  16. MD (Dremov, et al.) Self-Irradiation MD(Dremov, et al.)

  17. Modeling -Pu with GEAM Potential T=100K, Total time of modeling = 100 ps Russian Federal Nuclear Centre – Institute of Technical Physics

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