Heterogeneous materials design for sustainable nuclear waste storage using life prediction by conformal finite element analysis

Abstract

The durability of heterogeneous nuclear waste forms depends on the individual constituent properties as well as their internal morphology and boundary conditions. The end of life is defined by mechanical and chemical failure modes. Chemical failure occurs when increasing porosity reaches a threshold value, creating continuous pathways for the internal material to come in contact with the outside environment. Mechanical failure occurs when the waste form loses its structural strength due to porosity. In this work we employ conformal finite element analysis of heterogeneous waste forms set on the actual microstructure determined by tomography. The model calculates species flux in the constituents and the composite waste form subjected to various storage environments to estimate the development of porosity with time and the subsequent life. The analytical approach with preliminary results is discussed. The method is postulated to be a foundation for design of heterogeneous waste form materials.