Glossary / Nuclear fusion
Breeding blanket
The layer surrounding a fusion reactor's plasma. Neutrons striking lithium in it produce tritium fuel, and their energy is captured as heat.
Tritium, the fuel for D-T fusion, hardly exists in nature, so a reactor must keep making its own. Neutrons escaping the plasma produce tritium when they hit lithium, and the breeding blanket is where that happens. It also absorbs the heat that will drive power generation.
Whether a blanket can make more tritium than the reactor burns — a breeding ratio above one — has not yet been tested with real fusion neutrons. It needs materials and structures that survive heat, intense neutrons and strong magnetic fields at once, and is counted among the biggest challenges on the way to a demonstration reactor[1].
Related terms
- D-T fusionThe fusion of deuterium (D) and tritium (T) into a helium-4 nucleus and a neutron. Almost every fusion reactor now under development is built around this reaction.
- TokamakA doughnut-shaped machine that confines plasma by combining the magnetic field of external coils with the field produced by a current driven through the plasma itself. The dominant approach to magnetic confinement.