PILOT HYBRID EXPERIMENT WITH REVERSED FIELD PINCH AS NEUTRON SOURCE AND DOUBLE FISSION TEST BEDS: AN INNOVATIVE STAGE APPROACH TOWARDS A FULL POWER FUSION-FISSION HYBRID REACTOR

A novel approach to fusion-fission hybrid reactors (FFHR) has been proposed in recent years, regarding the fusion core for high energy neutron production, based on a Reversed Field Pinch (RFP) [1] [2] [3]. The authors specify that these studies are only based on calculations and computer simulations and any experimental activity involving nuclear fuel management is not planned. Main advantages of this configuration in a reactor perspectives with respect to the currently prevailing ones are: the internal toroidal field is self-generated by the current flowing in the plasma, allowing the use of "light" room temperature toroidal field coils rated for hundreds of milliTesla; no intrinsic current limit exists, so that increasing the plasma current, the ignition could be achievable by ohmic heating only, avoiding the use of additional heating systems; the configuration is not prone to disruption. In principle it could be also avoided the need of a divertor, so further simplifying the machine design. However, till now, a price has to be paid in terms of a partly chaotic character of the magnetic field leading to a poorer plasma confinement. Fortunately, advancements in RFP confinement have suggested modifications to the RFX-mod experiment (the largest RFP machine in operation) which are expected to decrease magnetic chaos and to improve significantly confinement. These enhancements are underway and the restart of the machine is foreseen in the next year. In order to cover the gap between the present status of the RFP as a fusion core and the knowledge necessary in designing the fission subcritical reactor with respect to the full power FFHR, a pilot FFHR based on a RFP operating with an energy gain Q near one has been conceived and the feasibility studies are underway [4]. ...