Multi Scale Study of Self-irradiation Effects in Plutonium Alloys

Abstract

AbstractExperimental measurements have shown that plutonium alloys exhibit changes of their macroscopic as well as microscopic properties. For example, a swelling of plutonium alloys was observed with aging with dilatometry and X-ray diffraction. The main idea to explain these changes rises in self irradiation undergoing by those materials. Plutonium α decay is at the origin of displacements cascades creating a large amount of structural defects. These later by anihilation and recombination give rise to larger defects such as voids and clusters. The aim of this work is to study the occurrence of such phenomena combining ab-initio, molecular dynamic and Monte Carlo methods in a coherent multi-scale approach which would help to understand long term behavior of structural defects and consequences of self irradiation. We show that plutonium does not seem to behave like other metals under ion irradiation. We discuss results obtained for high energy displacements cascade simulations. After parametric study of displacements cascade simulations combining temperature and cascade energy has been exposed, superposition of low energies displacements cascades is discussed as a method to construct realistic defect microstructures and to reach a rational use of computational time. At the end, we will present results of preliminary Monte Carlo simulations based on our molecular dynamic data which show that the spatial correlation of the stable defects populations created by the cascades seems to have a great influence on the predicted swelling.