ICONE23-1047 YTTRIA STABILIZED ZIRCONIA AS A HOT CORROSION PROTECTION OF FUEL CLADDING

Abstract

The zirconium alloys are used in nuclear engineering for decades, as a fuel cladding or other parts of the fuel assembly. It is an extraordinary material thanks to its good mechanical and neutronic properties. Unfortunately due to the high temperature oxidation it is necessary to protect parts of reactor against the cracking of material which could be severe for whole reactor. One of the promising protecting material is a zirconium dioxide which is forming on a pure zirconium in contact with air. But this dioxide, zirconia, is not stable because of destabilization and transformation of phases upon the cooling. To stabilize zirconia many other oxides may be added (MgO, Y_2O_3, CeO_2, etc.). Especially the yttrium stabilized zirconia (YSZ) shown significant advantages. In order to enhance the stability of YSZ beyond 1200℃, the further doping of system with other elements is required. So far the Ta_2O_5 addition, creating TaYSZ, is the best candidate with the best hot corrosion resistance properties, so the most promising material for protection of fuel cladding against corrosion degradation.