Prerequisites:

Description:

    Nuclear physics is the description of radioactive and other nuclear phenomena via quantum mechanics.  Although the phenomena are statistical, the numbers of atoms involved are so huge that nuclear physics is able to predict the results precisely. 
    Fissionables refining is the technology of getting heavy radioactive ores out of the ground and refining just the radioactive isotopes out of them.  This material is then useful both for fission power, and for fission explosives.
    Fusile Volatiles production is the technology of producing the specific isotopes of Hydrogen, Helium and Lithium which are useful for fusion activities.  These can be either (a) found in very small quantities in nature, or (b) produced by bombarding naturally occurring isotopes with neutrons from a fission reactor to produce more exotic isotopes.  Not all such isotopes occur in nature at all, as some have half-lives too short to last the billions of years which would have been necessary.
    While it is technically possible to create fission weapons without the use of fission power, it is far easier (industrially) to just build breeder-type reactors to get the material for the core explosive.  Uranium-based fission explosives are really just demonstration models; they are not practical for large-scale production.