Submitted by DanTheTerrible t3_zslth0 in askscience
In discussions of fusion research online, I keep finding statements that the preferred fusion fuel is a combination of Deuterium and Tritium. Deuterium is readily available in nature, but the Tritium has to be manufactured. The commonly stated scheme is to bombard Lithium-6 with neutrons from the fusion reaction, which will (usually?) cause the Lithium-6 nucleus to split into Tritium plus an alpha particle. What I can't understand is how this can produce enough Tritium to maintain fusion. One D-T fusion reaction produces one neutron, and one neutron causes one Lithium-6 nucleus to produce a Tritium ion -- for this to work, it seems we are requiring perfect 100% efficiency of fusion neutrons producing Lithium fuel. My engineering background refuses to believe it. 100% efficiency is a fantasy, some of those fusion neutrons are going to escape the Lithium blanket without reacting, and some will get involved in reactions that don't produce Tritium. Thus the fuel cycle I keep seeing described can't possibly produce enough Tritium to keep fusion going indefinitely. Is there some mechanism I haven't run across that produces extra Tritium or extra neutrons somehow?
ivonshnitzel t1_j18rrka wrote
Short answer is that there are ways to make neutrons produce more than one triton. Neutrons can react with lithium-7 to produce tritium + a neutron (which can then go on to react with another lithium-6 or lithium-7 nucleus to produce more tritium). Neutron multipliers such as beryllium that react with neutrons to produce two neutrons can also be included in the tritium bleeding blanket.