How a fusion power plant breeds, extracts, purifies, and recycles its own tritium fuel — the closed loop that makes D–T fusion self-sustaining and why it is one of the hardest engineering challenges in fusion.
Tritium, the radioactive hydrogen isotope needed for D–T fusion, does not exist in nature in useful quantities. The world’s entire supply (about 25 kg, mostly from Canadian CANDU reactors) is shrinking through radioactive decay (half-life: 12.3 years). A fusion power plant burning 100–200 kg of tritium per year must breed its own fuel.[1]
Breeding blanket: Contains lithium (as ceramic pebbles, liquid metal, or molten salt) surrounding the plasma. Neutron multipliers (beryllium or lead) boost the neutron count.[2]
Tritium extraction: Different blanket concepts extract tritium in different ways — helium purge gas sweeps it from solid breeders; permeation and vacuum extraction remove it from liquid metals.
Isotope separation: The exhaust gas from the plasma contains unburned D and T plus helium ash. Cryogenic distillation or other methods separate the isotopes for recycling.
No tritium breeding blanket has ever been tested in a fusion neutron environment. ITER will test six different blanket modules, but a full self-sufficient fuel cycle will first be demonstrated by DEMO or a fusion pilot plant. Achieving TBR > 1.0 while managing tritium inventory, permeation, and safety is considered one of the top three unsolved fusion engineering problems.[3]