Lithium stabilization of amorphous ZrO2

Small modular reactors (SMRs) are a key option to aid the worldwide net zero targets for carbon emissions. Some pressurised water reactors aim to operate with a boron-free coolant chemistry for simplification in plant design. In the absence of boron, Li has been found to accelerate the corrosion of the zirconium-based alloy fuel cladding under certain conditions and concentrations within pressurised water reactors (PWRs). The cause of the accelerated corrosion has yet to be identified. This work identifies the potential for amorphous ZrO2 phase stabilization by lithium that will potentially have an impact on the passive oxide's grain boundary structure. Higher lithium concentrations are found to stabilise the amorphous phase's stability before re-crystallisation to higher temperatures. Chemical assessment has also shown the lithium phase to be soluble in water, indicating a potential mechanism for lithium to alter grain boundaries and increase the pathways for further oxidation of the underlying zirconium material.