Power production and environmental aspects of a fusion-hybrid reactor

The fusion hybrid reactor has been identified by such Nobel Laureates as Bethe and Sakharov as the system that will meet the world's carbon-free energy needs of the next several decades when its population is expected to reach 10 billion with a power demand of about 30 TWs. Such a reactor will consist of a fusion component surrounded by a blanket containing fertile material, with the fusion component serving primarily as a neutron source. As such, it can operate at or near “breakeven” condition, a much less stringent condition than that required for a pure fusion reactor. When fusion neutrons impinge on a blanket made of thorium-232, they will breed uranium-233, and simultaneously burn it to produce power. Since only 15% of the 14.1 MeV neutrons generated by DT reactions captured in thorium-232 are estimated to undergo fission, the remainder will undergo various (n, xn) nuclear reactions that lead to the build-up of actinides. That build-up will diminish drastically if the neutrons are thermalized by the inclusion of a moderator and, in so doing, significant enhancement in power production will follow. Preliminary analysis of a fusion hybrid reactor based on a Gasdynamic mirror (GDM) confined DT plasma, shows that 10 megawatts of thermal power per centimeter of length can be readily achievable, with a small fraction of the electric power produced needed to sustain the fusion reactions. Such a reactor is found to be “safe” since it will be “subcritical” and “proliferation” resistant since the uranium-232 formed along the U-233 is known to have decay products that emit energetic and dangerous gamma rays. From an environmental standpoint we find that the thorium fuel cycle waste has a radiotoxicity period of less than 200 years which compares favorably with the more than 10,000 year radiotoxicity estimated to exist for the uranium fuel cycle waste. Similar trends are shown to exist for the decay heat of both of these fuel cycles.