Plentiful Tritium generation by a FFHR to feed a fusion power plant with simplified blanket

Tritium production, a key element in the implementation of D-T fusion, is one of the main challenges in developing fusion power plants. The paper reports on a feasibility study of a Fusion-Fission Hybrid Reactor (FFHR) devoted to the production of Tritium in amounts that could feed a fusion power plant with a simplified blanket, not required to breed tritium. The FFHR combines a low gain fusion core (Q ≈ 1) with a fissile blanket dedicated to Tritium breeding, working in a sub-critical condition. The low power (about a hundred MW) and the low gain make a fusion core based on a Reversed Field Pinch (RFP) configuration attractive for its advantages related to the purely plasma ohmic heating and the light toroidal field coils, rated for some tens of milliTesla. The preliminary design of such a reactor is reported in order to verify its feasibility with respect to various physical and engineering aspects (plasma performance, coil systems, circuit operation, layout, mechanical stresses and neutron shield), as well its convenience in terms of layout simplicity and increased space for the fissile blanket, when compared to Tokamaks. Using MCNP simulations, a fissile blanket composed of two fission modules (fast and thermal) was optimized for Tritium production. To maximize the neutron density, a dense ceramic fuel (MOX) is placed adjacent to a Lithium box in which high thermal neutron density breeds Tritium. The reactor meets safety requirements through subcriticality and advanced shielding structures. Preliminary results indicate high Tritium breeding efficiency, suggesting promising synergy with the future development of fusion power plants.