In multistage fission-fusion weapons, full yield of the fission primary that fails to initiate fusion ignition in the fusion secondary is also considered a "fizzle", as the weapon failed to reach its design yield despite the fission primary working correctly. Such fizzles can have very high yields, as in the case of Castle Koon, where a device with a 1 megaton design yield underwent a fusion fizzle, but its primary still generated a yield of 110 kilotons.