Simulation and Modelling the Heterogeneous Effects of the Microstructure MOX Fuels on their Effective Properties in Nominal Pressure Water Reactor Conditions

Abstract:

The experimental Electron Probe Micro Analysis (EPMA) characterizations on the MOX fuels evidence a heterogeneous microstructure, containing several phases. This heterogeneity must be accounted for in the numerical simulation. The first phase of this work, presented here, concerns exclusively the numerical representation of the MOX microstructure in three dimensions. Three identified steps were realized. The first one consisted in the acquisition and the treatment of two-dimensional experimental pictures thanks to a soft-ware already developed [1]. From the made treatments, the following bi-dimensional data were acquired: the surface fraction of every phase, the various diameters of inclusions within a phase as well as their surfaces fractions. However, within the framework of our study, we wished to represent our heterogeneous microstructure in three dimensions. Except, the data, supplied by this soft-ware, were bi-dimensional. Therefore, the second step of our works deal with the stereological domain. The model of Saltykov [2] was used to go back up the two-dimensional statistical information in three-dimensional. Finally, the last step of our works was to develop a tool able to build a meshed periodic numerical representation of the MOX microstructure. This innovative tool, based on a Random Sequential Absorption technique, represents MOX fuels already irradiated in reactor or any heterogeneous fuels envisaged in the future as well. For example it models two or three phases MOX fuel or any multi-phases fuels as well. Moreover, the sizes of the inclusions can vary within each phase. At the moment, the tool models spherical inclusions but nothing prevents from evolving towards more complex morphologies.

• Periodical: Advances in Science and Technology (Volume 73)
• Pages: 91-96
• DOI: https://doi.org/10.4028/www.scientific.net/AST.73.91
• Online since: October 2010
• Authors: Rodrigue Largenton, Victor Blanc, Philippe Thevenin, Daniel Baron
• Keywords: Heterogeneousness, MOX, Representative Elementary Volume, Three-Dimensional

References

[1] G. Oudinet : Analyse d'images et modélisation 2D/3D de la microstructure du combustible MOX, PhD Université Jean Monnet de Saint-Etienne (2003).

[2] S. Saltykov: The determination of the size distribution of particles in an opaque material from a measurement of the size distribution of their sections, Stereology proceedings of the second International congress for stereology (Chicago 1967).

DOI: 10.1007/978-3-642-88260-9_31

[3] V. Blanc: Modélisation du comportement des combustibles à particules par une approche multi-échelles. PhD, Université de Provence Aix Marseille I, (2009).