# Mechanical property evolution with radiation damage in (U,Pu)O$_2$ a MD simulation study

Abstract : Plutonium based MOX fuels (U,Pu)O$_2$ are one of the most commonly used fuel in actual nuclear plants in France. However, little is known on its microscopic behaviour during irradiation. This is mainly resulting from the fact that experiments are difficult and expensive to set up with such compounds at such scales and conditions. Hence, atomistic simulations can bring valuable information and increase the scope of knowledge in this field. Molecular dynamics simulations have proved to be an excellent tool to study point defects creation, because of its intrinsic length and time scales. First, we present in this paper the structural evolution in (U,Pu)O$_2$ solid solution under radiation. The primary damage created by displacement cascades up to 75 keV for different plutonium contents obtained with two different interatomic potentials are discussed. Subsequently, the evolution of the structural damage with dose is modelled by point defects accumulation method. With this method, we identify three stages for the formation of the extended defects with dose 1) point defects are created, 2) they cluster and form small Frank loops, and 3) these loops transform and grow into unfaulted loops. The effect of plutonium content is also evidenced, especially with Cooper's potential. It shows that the dislocation density decreases when the plutonium content increases.Second, with this set of damaged structures, we analyze the mechanical properties as a function of dose and plutonium content. The elastic constants, ultimate tensile stress, and toughness evolution are presented.
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https://hal-cea.archives-ouvertes.fr/cea-02400197
Submitted on : Monday, December 9, 2019 - 3:44:56 PM
Last modification on : Thursday, June 25, 2020 - 2:54:34 PM
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201800001655.pdf
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• HAL Id : cea-02400197, version 1

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L. van Brutzel, H. Balboa, A. Chartier. Mechanical property evolution with radiation damage in (U,Pu)O$_2$ a MD simulation study. NUMAT 2018, Oct 2018, Seattle, United States. ⟨cea-02400197⟩

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