Oxygen in the Liquid-Metal Fusion Reactor Blanket and Its Possible Influence on the Compatibility with Materials

Electrochemical oxygen meters with yttrium-doped thoria, yttrium-stabilized zirconia, and calcium-stabilized zirconia solid electrolytes are tested for the measurement of oxygen activity in Pb-17Li eutectic alloy, the proposed breeder blanket fluid for fusion reactors. The oxygen potentials of the alloy measured by these three meters are compared with the oxygen potentials of the alloy after the addition of lithium oxide and with theoretical values. Zirconium and yttrium metal foils are tested for gettering oxygen from the alloy. The compatibility of the three ceramic materials in the liquid alloy and the stability of the meters for prolonged use are discussed. The influence of oxygen on the corrosion of steels in Pb-17Li is reviewed in light of the oxygen potentials of the alloy compared to thermodynamic data of the ternary oxides of the metal constituents of steels. The possibility of using the oxygen meters to measure the lithium activity of the alloy is also indicated.