Here is some good info about minimum payload (16kg) needed for fission http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html http://nuclearweaponarchive.org/Nwfaq

Here is some good info about minimum payload (16kg) needed for fission http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html