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Moscow, Russia

Inogamov N.A.,Russian Academy of Sciences | Zhakhovsky V.V.,University of South Florida | Petrov Y.V.,Russian Academy of Sciences | Khokhlov V.A.,Russian Academy of Sciences | And 13 more authors.
Contributions to Plasma Physics | Year: 2013

Fundamental physical phenomena in metals irradiated by ultrashort laser pulses with absorbed fluences higher than few tens of mJ/cm2 are investigated. For those fluences, laser-produced electron distribution function relaxes to equilibrium Fermi distribution with electron temperature Te within a short time of 10-100 fs. Because the electron subsystem has Te highly exceeding much the ion subsystem temperature Ti the well-known twotemperature hydrodynamic model (2T-HD) is used to evaluate heat propagation associated with hot conductive electron diffusion and electron-ion energy exchange. The model coefficients of electron heat conductivity κ (ρ{variant}, Te, Ti) and electron-ion coupling parameter α (ρ{variant}, Te) together with 2T equation of state E (ρ{variant}, Te, Ti) and P (ρ{variant}, Te, Ti) are calculated. Modeling with 2T-HD code shows transition of electron heat wave from supersonic to subsonic regime of prop-agation. At the moment of transition the heat wave emits a compression wave moving into the bulk of met al. Nonlinear evolution of the compression wave after its separation from the subsonic heat wave till spallation of rear-side layer of a film is traced in both 2T-HD modeling and molecular dynamics (MD) simulation. For fluences above some threshold the nucleation of voids in frontal surface layer is initiated by strong tensile wave following the compression wave. If the absorbed fluence is ~30 % above the ablation threshold than void nucleation develops quickly to heavily foam the molten met al. Long-term evolution of the metal foam including foam breaking and freezing is simulated. It is shown that surface nano-structures observed in experiments are produced by very fast cooling of surface molten layer followed by recrystallization of supercooled liquid in disintegrating foam having complex geometry. Characteristic lengths of such surface nanostructures, including frozen pikes and bubbles, are of the order of thickness of molten layer formed right after laser irradiation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Fedorov Yu.S.,Khlopin Radium Institute | Baryshnikov M.V.,State Corporation ROSATOM | Bibichev B.A.,Khlopin Radium Institute | Zilberman B.Ya.,Khlopin Radium Institute | And 2 more authors.
International Nuclear Fuel Cycle Conference, GLOBAL 2013: Nuclear Energy at a Crossroads | Year: 2013

REMIX fuel consumption in WWER-1000 is considered. REMIX fuel is fabricated from inseparated mixture of uranium and plutonium obtained during NPP spent fuel reprocessing with further makeup by enriched natural uranium. It makes possible to recycle several times the total amount of uranium and plutonium obtained from spent fuel with 100% loading of the WWER-1000 core. The stored SNF could be also involved in REMIX fuel cycle by enrichment of regenerated uranium. The same approach could be applied to closing the fuel cycle of CANDU reactors. Source

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