Neutronics assessment for the ARIES advanced reactor studies

The ARIES tokamak designs have incorporated environmental and safety constraints in the design from the beginning. Low activation materials such as SiC or SiC composites, vanadium alloy, and modified HT-9 ferritic steel were utilized as the main structures in ARIES-IV, II, and III, respectively. All designs employ D-T fuel cycles except ARIES-III which is D-3He fuelled. An overall tritium breeding ratio of 1.12 seems adequate for ARIES-II and IV. The Li2O breeder requires a beryllium multiplier to achieve T self-sufficiency in the ARIES-IV design while the lithium has the ability to breed sufficient T in ARIES-II without a multiplier. Radiation damage concerns for the structures are the burn-up of the SiC and SiC composites and the atomic displacement in the vanadium. The first wall and blanket require frequent replacement (every 3–4 years) during reactor operation. The end-of-life fluences are 16.5 MW years m−2 and 13 MW years m−2 based on the 200 dpa and 3% burn-up limits for the V and SiC structures respectively. Because of the lower neutron production, the ARIES-III first wall and shield are permanent components and require no replacement over the plant lifetime. A variety of shield options was examined and the ability of various materials to protect the magnets was assessed. At least 1.2 m and 1.4 m of inboard blanket-shield are required for magnet protection in ARIES-II and ARIES-IV respectively. The lack of T breeding and the lower wall loading result in a much thinner shield (0.65 m) for ARIES-III.