High-Burnup Spent Nuclear Fuel Interface Bonding Efficiency Study

To investigate the impact of interfacial bonding efficiency at pellet-pellet and pellet-clad interfaces of high-burnup (HBU) spent nuclear fuel (SNF) on system dynamic performance, the finite element analyses (FEA) simulations were performed on H. B. Robinson (HBR) fuel rod. The interfacial layer was modeled as a cohesive bonding medium. Bending moments M were applied to FEA model to evaluate the system responses. From the resultant bending curvature, ?, flexural rigidity EI can be estimated as EI = M/?. The FEA simulation results were benchmarked with experimental results from Cyclic Integrated Reversal Bending Fatigue Tester (CIRFT) data of HBR fuel rods. The immediate consequence of interface debonding is a shift in load-carrying capacity from the fuel pellets to the clad, which results in a reduction in composite rod system flexural rigidity. Therefore, the interface bonding efficiency at the pellet-pellet and pellet-clad interfaces can significantly dictate the SNF system dynamic performance.