Processing and characterization of surrogate nuclear materials with controlled radial porosity

ABSTRACTIrradiated fuel pellets present radial gradient porosity. CeO2 has been proven as a surrogate material to understand irradiated mixed oxide (MOX) due to its similar structural and mechanical properties. A novel compaction device was developed to produce CeO2 cylindrical pellets with controlled radial porosity. Three blends of CeO2 with different binder contents (0.5, 3 and 7.5 vol.% of ethylene-bis-stearamide, EBS) were prepared and used to obtain three different porosities for the core, intermediate and outer rings of pellets, respectively. Different compaction pressures were employed in each region to get the intended porosities. The whole pellet was subjected to a heating rate up to 500 °C to remove the EBS binder. Finally, a pressureless sintering step was performed at 1700 °C for 4 h. A microstructural characterization was performed in the three areas, including grain size and porosity. Mechanical properties like hardness, fracture toughness and tribo-mechanical response, as scratch resistanc...