Neutronic investigation of a hybrid version of the ARIES-RS fusion reactor

A hybrid version of the ARIES-RS of the commercial 1000 MWel power plant design concepts is investigated. A 10 cm fission zone at the inner blanket leads to a blanket multiplication of M=1.946 with ThC fuel or M=3.03 with UC fuel and increasing the fusion power from 2170 to 4200 MW or to 6500 MW, respectively. Despite a partial replacement of the lithium zone by the fissile zone, tritium breeding remains still >1.05, which will be required for a self-sustaining fusion driver. In addition to fusion power amplification, substantial fissile material will be produced at start-up conditions with a fission breeding rate of 233U=0.183 (with ThC) or 239Pu=0.263 (with UC) per incident fusion neutron, which correspond to 4410 kg 233U/year or 6500 kg239Pu/year, respectively, by a full fusion power of 2170 MW. Damage calculations are based on the neutron flux load of 3.7 MW/m2 and 5.6 MW/m2 and have resulted with DPA=31 and 78 at the inner and outer first wall, respectively. DPA limit on vanadium will then require a change of the first walls at the inner and outer blankets after 6.5 and 2.5 full power years, respectively. Helium production at the inner and outer first wall is calculated as 117 and 237 ppm, respectively. This would lead to a first wall change after 4 and 2 full power years at the inner and outer blankets, respectively. The spectrum softening in the fissile zone will cause a relatively lower material damage as compared with the pure fusion reactor design.