Development of Peridynamics Capability for Modeling of Metallic Nuclear Fuels

Task 1: Develop validated scheme to handle the shape tensor singularity due to insufficient active neighbors of a material point in ordinary state-based model for fracture modeling. This is critical to a complete simulation run without intermediate stop due to singularity of the shape tensor. This issue is essentially related to a state at which there are not sufficient bonds connected to a particle for its deformation gradient calculation. A solution based on the idea of sub horizon for a group of materials can be developed to handle this singularity issue. This scheme will first be implemented into the peridynamics module. Systematic study will be performed to establish its validity. Task 2: Develop failure criterion for creep-fracture modeling in peridynamics for metallic fuel. The current available failure criteria in the peridynamics modules are critical stretch and maximum principal stress. Both criteria are valid for oxide fuel due to its brittle fracture characteristics. However, for metallic fuel, due to severe creep deformation, the critical stretch criterion is no longer valid. The validity of the maximum principal stress criterion still need validation. Other failure criteria from fracture mechanics for inelastic materials will be studied and them applicability to metallic fuel will be examined. With the successful completion of this project, it’s anticipated that a valid failure criterion for metallic fuel will become available and the crack nucleation and propagation modeling and simulation of metallic fuel will become possible. Project Schedule and Deliverables The project duration is one year. Project starting date will be decided upon agreement between DOE and the PI. The primary deliverable of this project will be codes implemented into the peridynamics module in MOOSE framework. The secondary outcome will be published journal paper(s) on metallic fuel failure modeling and simulation using developed peridynamics model.