Lithium hydride
Before the Castle Bravo nuclear weapons test in 1954, it was thought that only the less common isotope lithium-6 would breed tritium when struck with fast neutrons. The Castle Bravo test showed (accidentally) that the more plentiful lithium-7 also does so under extreme conditions, albeit by an endothermic reaction.
B46 nuclear bomb
The design history of the B46 apparently derives most immediately from the older, larger Mark 21 nuclear bomb design, which was a design derivative of the Shrimp design which was the first US solid fueled thermonuclear bomb test fired in the Castle Bravo test.