Fusion Reactor Breeder Material Safety Compatibility Studies

Tritium breeder material selection for fusion reactors is strongly influenced by the desire to minimize safety and environmental concerns. Breeder material safety compatibility studies are being conducted to identify and characterize breeder-coolant-material interactions under postulated reactor accident conditions. Recently completed scoping compatibility tests indicate the following. 1. Ternary oxides (liAlO₂, Li₂ZrO₃, Li₄SiO₄, and liTiO₃) at postulated blanket operating temperatures are chemically compatible with water coolant, while liquid lithium and Li₇Pb₂ reactons with water generate heat, aerosol, and hydrogen. 2. Lithium oxide and 17Li-83Pb alloy react mildly with water requiring special precautions to control hydrogen. 3. Liquid lithium reacts subtantially, while 17Li83Pb alloy reacts mildly with concrete to produce hydrogen. 4. Liquid lithium-air reactions may present some major safety concerns. Additional scoping tests are needed, bot the ternary oxides, lithium oxide, and 17Li-83Pb have definite safety advantages over liquid lithium and Li₇pb₂. The ternary oxides present minimal safety-related problems when used with water as coolant, air, or concrete; but they do require neuton multipliers, which may have safety compatibility concerns of lithium oxide 17Li-83Pb make them prime candidates as breeder materials. Current safety efforts are directed toward assessing the compatibility of lithium oxide and the lithium-lead alloy with coolants and other materials.