Multi Scale Study of Self-irradiation Effects in Plutonium Alloys
- PDF / 273,334 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 107 Downloads / 203 Views
1104-NN07-11
Multi Scale Study of Self-irradiation Effects in Plutonium Alloys Lilian Berlu1, Gaëlle Rosa1, and Gérald Jomard2 1 CEA - Centre de Valduc, Is sur Tille, 21120, France 2 CEA - Bruyères le Châtel, Bruyères le Châtel, 91680, France
ABSTRACT Experimental 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. INTRODUCTION It is commonly believed that plutonium α-decay is at the origin of plutonium aging. This phenomenon would lead to the formation of numerous point defects in the metal structure that could affect material properties. Experimental measurements have shown that plutonium alloys swell during aging [1-6]. A multi-scales modeling approach has been developed in order to understand plutonium aging phenomena and to predict their consequences on material properties over years [4, 7-10]. This approach consists in the coupling of molecular modeling methods at different scales of the matter that is electronic scale with first principle calculations, atomic scale with molecular dynamics (MD), mesoscopic and macroscopic scales with Monte Carlo (MC) and rate equation (RE) simulations. Techniques related to each scale are parameterized with results delivered by smaller scales and available experimental data. Elastic constants and bulk modulus measurements together with first principle electronic structure and formation energies calculations were used to develop inter atomic potentials applied in MD models. The plutonium α decay was simulated by MD through displacements cascades which give rise to the formation of lattice defects. The number and the spatia
Data Loading...
