Meso-scale modeling of the influence of intergranular gas bubbles on effective thermal conductivity

Using a meso-scale modeling approach, we have investigated how intergranular fission gas bubbles, as observed in high-burn-up nuclear fuel, modify the effective thermal conductivity in a polycrystalline material. The calculations reveal that intergranular porosity has a significantly higher resistance to heat transfer compared to randomly-distributed porosity. A model is developed to describe this conductivity reduction that considers an effective grain boundary Kapitza resistance as a function of the fractional coverage of grain boundaries by bubbles.

[1]  G. Bai,et al.  Interfacial thermal resistance in nanocrystalline yttria-stabilized zirconia , 2002 .

[2]  Ce-Wen Nan,et al.  Determining the Kapitza resistance and the thermal conductivity of polycrystals: A simple model , 1998 .

[3]  Donald R. Olander,et al.  Fundamental Aspects of Nuclear Reactor Fuel Elements , 1976 .

[4]  M. Coster,et al.  Microstructural analysis and modelling of intergranular swelling of an irradiated UO2 fuel treated at high temperature , 1998 .

[5]  T. Reinecke,et al.  Thermal conductivity of opals and related composites , 2001 .

[6]  R. J. White,et al.  The development of grain-face porosity in irradiated oxide fuel , 2004 .

[7]  Chen,et al.  Computer simulation of the domain dynamics of a quenched system with a large number of nonconserved order parameters: The grain-growth kinetics. , 1994, Physical review. B, Condensed matter.

[8]  J. Francl,et al.  Thermal Conductivity: IX, Experimental Investigation of Effect of Porosity on Thermal Conductivity , 1954 .

[9]  M. Limbäck,et al.  Advanced Doped UO2 Pellets in LWR Applications , 2006 .

[10]  E. Thornton.  Viscosity and Thermal Conductivity of Binary Gas Mixtures: Xenon-Krypton, Xenon-Argon, Xenon-Neon and Xenon-Helium , 1960 .

[11]  A. L. Loeb.  Thermal Conductivity: VIII, A Theory of Thermal Conductivity of Porous Materials , 1954 .

[12]  Paul C. Millett,et al.  Phase-field simulation of thermal conductivity in porous polycrystalline microstructures , 2008 .

[13]  J. Maxwell.  A Treatise on Electricity and Magnetism , 1873, Nature.

[14]  P. Nikolopoulos,et al.  Conductivity bounds for porous nuclear fuels , 1983 .

[15]  H. Matzke,et al.  A Pragmatic Approach to Modelling Thermal Conductivity of Irradiated UO2 Fuel. Review and Recommendations , 1996 .

[16]  Rainer Telle,et al.  Thermal Resistance of Grain Boundaries in Alumina Ceramics and Refractories , 2003 .

[17]  A. El-Azab,et al.  Phase-field simulation of irradiated metals: Part II: Gas bubble kinetics , 2011 .

[18]  Orlando Auciello,et al.  Thermal transport and grain boundary conductance in ultrananocrystalline diamond thin films , 2006 .