IFE power plant design principles. Materials management and target materials recovery

Tritium and other target material must be recovered from the IFE reaction chamber exhaust gas and from the recirculating blanket and wall protection materials and must be supplied to the target factory for further use. Prudent management of the tritiated and other radioactive materials in the reaction chamber is essential for the economic and safe operation of the power plant. After each fusion pulse, vaporized gases in the chamber may include unburned fuel, helium produced by fusion reactions, atoms from beam ions, vaporized gases from the target shell pusher-tamper and material from the driver beam protection system. Vapour of liquid metals or fused salts used to protect the chamber wall will fill the chamber and condense, but a residue of them may also be in the exhaust. Directly illuminated fusion targets may be composed of the frozen fuel components in a single polymeric spherical shell. For direct drive the target could contain considerable amounts of hydrogen and CH2. This would produce exhaust gas containing up to 40% of atomic hydrogen, 21% atomic deuterium, 21% tritium, 18% helium and less than 1% impurities such as methane and carbon dioxide. Hohlraum targets will contain DT fuel, a pusher such as CH2 or BeO and a heavy metal tamper such as Ta, W, Pb, or Au. Target debris and ablated wall materials may be deposited in the chamber coolants and dissolve or form a fine colloidal suspension in the liquid metals or molten salts. They must be removed continuously, allowed to decay and be reused in targets. In this document the main functions of the materials management system of an IFE plant are discussed briefly based on the above considerations, in addition to tritium management in liquid metal protection chambers, molten salt protection chambers, and dry wall chambers. It is concluded that further development is needed on: (1) tritium separation from molten salts and liquid metals; (2) tritium removal from solids (e.g. C, SiC); (3) low tritium inventory hydrogen isotope separation; (4) durable tritium permeation barriers for heat exchanger tubes; and (5) separation of high Z target materials from coolants. 11 refs, 3 figs, 2 tabs