4-7 November 2019
PSI Auditorium
Europe/Zurich timezone
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Multi-scale nuclear fuel simulation with VER software

5 Nov 2019, 11:40
20m
WHGA/001 (PSI Auditorium)

WHGA/001

PSI Auditorium

Forschungstrasse 11 5232 Villigen PSI Switzerland

Speaker

Marcelle Ibrahim (CEA)

Description

PLEIADES is a scientific code platform dedicated to nuclear fuel
behaviour simulation for several types of reactors: water cooled
reactors, sodium cooled fast reactors, research and material testing
reactors, etc. In this platform, the microstructures of these
different types of fuel are studied using VER software (Representative
Elementary Volume). These studies aim at the comprehension of the
thermo-mechanical phenomena at the microscopic scale, and their
homogenisation for implementation of their effective behaviour in fuel
performance codes. Here are some applications:

  • UO$_2$ fuel is a poly-crystalline ceramic
    (Figure 1). The mechanical behaviour of each
    crystal can be modelled with crystalline plasticity, based on
    dislocation mouvement. An overall behaviour is then deduced by
    homogenisation.
  • MOX fuel contains heterogeneity due to the variation of Pu
    concentration on a microscopic scale. This can lead to stress and
    strain concentration near the Pu rich agglomerate. This
    heterogeneity can be simulated either with discontinuous geometry
    (Pu rich inclusions in Pu poor matrix, Figure 2), or
    with continuous Pu field (Figure 3). The
    macroscopic mechanical behaviour is established using homogenisation
    methods such as Mori-Tanaka or reduction techniques like Nonuniform
    Transformation Field Analysis.
  • In some fuels, flat porosity is formed around the
    agglomerates. Simulations of these microstructures are carried out
    (Figure 4) in order to study the degradation of the
    fuel conductivity due to this porosity.
  • For accident tolerant fuel, new concepts are studied, such as adding
    a highly conductive phase to the fuel. This is shown in
    Figure 5, where the metal phase around the agglomerates
    enhances the pellet conductivity.

Primary author

Marcelle Ibrahim (CEA)

Co-authors

Dr Luc Portelette (CEA) Mr Akram El Abdi (CEA) Mrs Joane-Valerie MEYNARD (CEA) Dr Bernard Valentin (CEA)

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