A Fusion-Fission Implementation of the 
Hybrid Molten Salt Reactor (HMSR)

Author:   Robert D. Woolley

Abstract:  The Hybrid Molten Salt Reactor (HMSR) is an advanced unconventional nuclear reactor concept whose single liquid fuel loop combines critical fission in a thermal spectrum molten salt reactor (MSR) with a driven source of fusion or spallation neutrons having energies an order of magnitude above the fission spectrum. Its resulting bimodal effective spectrum allows a low fissile inventory, while fissioning any actinide mix including spent nuclear fuel, depleted uranium, natural uranium or thorium. When further combined with continuous fission product removal and fuel addition, resource utilization rises to 100%, while actinides are entirely eliminated from the radioactive waste stream and both fuel enrichment and fuel recycling become unnecessary. Key to the HMSR is its energetic neutron source. Simulations show that average energetic neutron power for steady fixed-point system operation, in which the entire blend of dissolved isotopes remains constant over time, can be less than 1% of total plant power. This fact may allow near term HMSR deployment using already-demonstrated fusion performance. This paper proposes an implementation of the energetic neutron source tailored to the HMSR application using presently existing fusion technology. It is a tokamak which repetitively and with high duty cycle generates pulsed DT plasmas heated to thermonuclear fusion temperatures by neutral beams.
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