Fissile Fuel Breeding and Actinide Transmutation in an Inertial Fusion Energy Reactor

Full text: Macro scale fusion projects are ITER on magnetic fusion energy (MFE) and NIF on inertial fusion energy (IFE). While ITER is still on design stage, NIF will become fully operational early 2011. Preliminary design studies on a Laser Inertial Confinement Fusion Fission Energy (LIFE) reactor concept have been initiated at LLNL, based on NIF. LIFE has a spherical fusion chamber of 5 m diameter, a thin LiPb coolant behind an ODS first wall, followed by a beryllium multiplier, fission blanket and graphite reflector. However, beryllium multiplier will soften neutron spectrum leading to local heat peaks. In the present work, a modified LIFE blanket has been investigated consisting of ODS-first wall (2 cm); Li17Pb83 as neutron multiplier+coolant; ODS-separator (2 cm); Flibe (Li2BeF4) coolant and fission zone; ODS-separator (2 cm); graphite reflector. The study covers fissile fuel breeding and minor actinide transmutation. Tritium breeding ratio (TBR) is kept > 1.05. Thicknesses of blanket zones have been determined as 10 cm Li17Pb83; 50 cm Flibe and 30 cm graphite reflector, leading to T BR =1.134 without fissionable material. Addition of fissionable fuel decreases TBR. A volume fraction of 2% TRISO particles with nat-UC in molten salt yields T BR =1.0514. Minor actinide have superior nuclear properties at high energies and lead to higher neutron multiplication under 14 MeV fusion neutron irradiation. One obtains T BR =1.05 by 11 vol.% of TRISO particles containing minor actinides. Furthermore, time evolution of fissile and fusile fuel breeding, figure-of-merit (plutonium production/MW-fusion power), actinide transmutation over operation, material damage on structures with respect to DPA, He and H production, and Shallow burial index for final decommissioning are being evaluated. (author)