>Castle Bravo, the biggest US bomb ever tested, was also heavily fusion (and big thanks to the unexpected lithium 7 tritium bonus), though I think you're right

>Castle Bravo, the biggest US bomb ever tested, was also heavily fusion (and big thanks to the unexpected lithium 7 tritium bonus), though I think you're right that a lot of ultimate yield was from fission of the natural uranium tamper. It seems to be generally accepted that 10Mt (two thirds) of the yield in Castle Bravo was indeed from fast fission of the tamper.