Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

Fission fragment direct energy conversion (FFDEC) into electricity can dramatically improve the specific mass of fission-based electric propulsion rocket.

An EPRI study by A. G. Tarditi, J. H. Scott focused on the conversion via traveling wave DEC (direct energy conversion), that has the advantage of being able to generate high frequency power (MHz range) and does not require high voltage technology, unlike electrostatic energy conversion.

The fission fragment direct energy conversion (FFDEC) is considered as a best fit to an accelerator-driven fission core to improve the efficiency and the overall specific mass.

This proposed approach is complementary to the fission fragment direct utilization for propulsion since it can provide a more versatile scenario where a lower Isp is provided by plasma acceleration while at the same time some of the extremely high Isp provided by the fission fragment beam is being reduced.

Direct energy conversion instead of steam cycle (conversion of heat to electrical energy)
– Less heat: less radiators
– No pumps, pipes, generators: lowering mass
– Lowering mass + Improving efficiency

Fission fragments need thin fissile fuel elements
• Fragments carry large positive charge (≈20 e) and can be collimated with magnetic fields
• Traveling Wave DEC converts fragment energy into AC electric power
• Subcritical fission driven systems combined with fission DEC may become the most efficient option

Feasibility of Traveling Wave Direct Energy Conversion of
Fission Reaction Fragments

Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics