Status and Perspective of a Reversed Field Pinch as Fusion Core in a Fusion-Fission Hybrid Reactor

Fusion-fission hybrid reactors (FFHR), which consist of a neutron-producing fusion core surrounded by a fission blanket, keep a sustained interest because of their potential to address energy production before the availability of pure fusion reactors and also because of their capability of fuel supply and waste management. The U.S. Department of Energy (DOE) sponsored a workshop in 2009 in order to assess the potentiality of fusion-fission reactors and, among the others alternative to the Tokamak as fusion core, the Reversed Field Pinch (RFP) was considered, even if not on the same timeline of the Tokamak. On the other hand, the interest in the RFP as fusion core resides, inter alia, in its possibility to reach ignition in a pure ohmic way with a "light" toroidal field winding, which simplifies significantly the hybrid reactor layout and operation and strongly decreases costs with respect to other fusion core solutions. New studies are now in progress in order to revisit the status and the potentiality of the RFP as fusion core in FFHR, taking into account (i) the recent progress in RFP physics brought by the results of the RFX-mod experiment (R=2, a=0.46, Ip=2MA), mainly about MHD modes control, (ii) the expected performance improvements resulting from the ongoing upgrade of the machine. Starting from RFX-mod results and scaling laws, and considering the estimated improvements of the performances derived from the machine enhancements underway, the possibility to realize a preliminary pilot experiment in which a RFP is the neutron fusion source is analysed. The research needs for this advanced solution are updated with respect to the 2009 workshop.