This is a great article on First Light's tritium production: https://nickhawker.com/2023/01/22/the-nuclear-physics-of-why-tritium-is-a-challenge-for-fusion-en

This is a great article on First Light's tritium production: https://nickhawker.com/2023/01/22/the-nuclear-physics-of-why-tritium-is-a-challenge-for-fusion-engineering/ https://nickhawker.com/2023/01/22/the-nuclear-physics-of-why... Summing up: you need your fusion neutrons to breed more tritium from lithium. Lithium-7 produces tritium plus a lower-energy neutron that can breed one more tritium. Lithium-6 produces tritium but without the extra neutron. Most designs lose a lot of neutrons, so they have to either enrich lithium for more lithium-7, or (most commonly) mix in either lead or beryllium as a neutron multiplier. First Light's design captures 99% of the neutrons, so they think they can breed 50% more tritium than they consume with just natural lithium.