Swelling and microcracking of boron carbide subjected to fast neutron irradiations

The neutron absorbing ceramic boron carbide was irradiated in the Phenix fast breeder reactor between 600 and 1500 °C. Selected pellets were observed at different magnifications using optical ceramography, scanning electron microscopy, and transmission electron microscopy. The bulk swelling was measured as a function of the burn-up and compared to a recent model based on microstructural observations. Intergranular microcracking was identified as the main source of troubles in the use of boron carbide at high fluence levels and studied in relation with our recent models.