Effect of Irradiation on the Tensile Strength of Select Layers and Layer Interfaces of TRISO-coated Nuclear Fuel Particles

Tri-structural isotropic (TRISO) coated nuclear fuel particles are of interest for new reactor designs; however, knowledge gaps exist about mechanical properties of particle coating layers. To fill this gap, micro-scale tensile strength testing of layers is being conducted. Samples from particles are prepared via FIB micromachining and tested in-situ SEM. Of particular interest are buffer carbon and IPyC layers and their interface. To date, all interface samples fractured inside the buffer layer. Buffer and IPyC layer testing confirms the buffer is weaker. Interface samples testing indicates they have greater average tensile strength than buffer samples. Some interlayer samples displayed stress-strain behavior similar to IPyC. This behavior suggests the IPyC layer may play a larger role in buffer-IPyC interface properties than previously suspected. Surrogate fuel layer samples have been tested and pre-irradiated fueled and irradiated fueled samples are currently under investigation. Complete results will be available at the symposium.