OT but are there any links to resources about using fission/fusion bombs directly for energy production?
I want to say that fusion bombs require more energy input than they output, because until recently nobody has been able to create fusion reactions otherwise (and now only in a very limited way). But is that true? Fusion bombs release an incredible amount of energy. Maybe it's that they release it all at once, but still, how does that equation work out?
Good question. I should have asked strictly about fusion bombs. These being a known-working example of energy production by fusion, why not use them when we can't get 'controlled' fusion working?
So my takeaway is that fission bombs are not very efficient to begin with. You're after all trying to extract as much energy as possible as quickly as possible from a system that is literally self destructing. We do not have that constraint with current fission plants, the plant is designed to run in a steady state for years, the fissile materials stay in place and my intuition is that this significantly helps efficiency.
This is yet another reason that fusion research is expensive and time consuming, the cost involved in manufacturing these components and time lost in painstaking teardowns and overhauls between test runs.
The problem is that explosions of that magnitude are not usable for controlled energy generation. Confining them underground is impractical, due to the scale of energy release. The largest underground US test was 5 megatons in 1971, and it was so disruptive (induced surface motion equivalent to an earthquake) that it had to be conducted at a remote Alaskan island instead of the usual Nevada test site [2].
For those reasons, Project PACER considered bombs of only up to 50 kilotons. At those sizes (0.5% the energy yield of Housatonic), there is no known design to get 90%+ of the bomb's energy yield from fusion. The efficient fusion designs don't gracefully scale down to that range. And at that much smaller scale where underground confinement was practical, bombs were not actually any cheaper as a source of raw thermal energy. Quoting Wikipedia about the project here, "In a 1975 review of the various Plowshares efforts, the Gulf University Research Consortium (GURC) considered the economics of the PACER concept. They demonstrated that the cost of the nuclear explosives would be the equivalent of fuelling a conventional light-water reactor with uranium fuel at a price of $328 per pound. Prices for yellowcake at that point were $27 a pound."
[1] "Ripple: An Investigation of the World’s Most Advanced High-Yield Thermonuclear Weapon Design" http://web.mit.edu/zoz/Public/jcws_a_01011.pdf