Physics of Fusion Fuel Cycles

The evaluation of nuclear fusion fuels for a magnetic fusion economy must take into account the various technological impacts of the various fusion fuel cycles as well as the relative reactivity and the required betas, temperatures, and confinement times necessary for economic steady-state burns. The physics of the various fuel cycles [deuterium-tritium, catalyzed deuterium-deuterium (D-D), D-³He, D-⁶Li, and the exotic fuels: ³He-³He and the proton-based fuels ρ-⁶Li, ρ-⁹Be, and ρ-¹¹B] is reviewed. Topics considered include

1. fuel costs and required purity
2. tritium inventory, burnup, and recycle
3. ignition criteria
4. neutrons
5. condensable fuels and ashes
6. radiation losses
7. direct electrical recovery prospects
8. fissile breeding prospects.

The advantages and disadvantages of each fuel are also treated. The optimum fuel cycle from an overall standpoint of viability and potential technological considerations appears to be catalyzed D-D, which could also support smaller, relatively “clean,” lean deuterium-rich ³He satellite reactors as well as fission reactors.