Neutronics issues for Starlight: an inertial confinement fusion reactor concept

The author discusses an evolving design, reporting results of 1- and 2-D calculations involving tritium breeding, neutron damage, and the beam port neutron leakage. The author concludes that an inertial confinement fusion (ICF) reactor using a solid breeder is feasible. A low-temperature option uses a steel first wall and Li₂O as the breeding material. This first wall has an expected lifetime of more than six years. Up to a 10-cm thickness can be tolerated before the tritium breeding ratio falls below unity. The author is unaware of a suitable high-temperature first wall material for a high-temperature option. This option would use a ceramic first wall and breed tritium in LiAlO₂ allowing all the reactor components to operate at high temperatures that allow efficient use of He as a coolant. Of the ceramics examined, SiC appears to be the best choice for considering both tritium breeding and wall lifetime. However, He production will limit that lifetime to five months, clearly not an economical lifetime. Further, Li₂O is necessary rather than LiAlO₂ (at 7-cm wall thickness) to achieve a favorable tritium breeding ratio with SiC. Here, the benefits of using ceramics are lost as Li₂O has a much lower melting point than LiAlO₂