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.
Operation Crosstie
The Faultless test was a calibration test conducted in a mine cavity 3,200 feet beneath the Hot Creek Valley near Tonopah, Nevada, with a yield of around 1 megaton. This test was conducted to see if the land was fit for testing a 5 megaton thermonuclear warhead for the Spartan missile. The test failed because of the large degree of faulting that resulted in the area around the test. It was decided that the land was unfit for multi-megaton nuclear tests, so a similar calibration test was conducted at Amchitka Island, Alaska, in the fall of 1969 during Operation Mandrel.