No major abundance technology sits more uncomfortably on the civilian/military boundary than nuclear fission. The same physics that enabled the first weapons enabled the first reactors, and the institutions, supply chains, and anxieties of the two applications have been entangled ever since.
From weapons program to reactors
The Manhattan Project's industrial base — enrichment plants, plutonium production reactors, and a large trained workforce — was repurposed after the war into both a nuclear-weapons complex and a civilian reactor program. Many early civilian reactor designs descended from naval-propulsion reactors developed for submarines. The institutional choice to industrialize pressurized-water reactors first, rather than alternative designs that might have had different safety or waste profiles, was shaped heavily by this military lineage.
The abundance case
Fission remains one of the few proven, scalable, low-carbon sources of firm electrical power. In scenarios where solar, wind, and storage are insufficient on their own — for example, high-latitude grids, heavy industry, and certain kinds of heat applications — expanded civilian fission is part of most credible paths to Energy Abundance. The Fusion Era, if it arrives, inherits much of the regulatory, workforce, and public-trust infrastructure built up around fission, for better and worse.
Costs honestly stated
The civilian dividend is not free. Fission produced long-lived waste whose disposal is still politically unresolved in most jurisdictions. Major accidents — Three Mile Island, Chernobyl, Fukushima — imposed real human, ecological, and economic costs. Proliferation risk, in which civilian fuel cycles contribute to weapons capability, is built into the technology rather than incidental to it. An honest abundance account treats these as design constraints rather than footnotes.
Open questions
Would a purely civilian path to fission — one that prioritized walk-away-safe designs, closed fuel cycles, or thorium from the beginning — have produced a different and more trusted industry? The historical record does not settle the question. Looking forward, the key issues are whether small modular reactors and advanced fission concepts can be licensed and built at a cadence that matters for climate timelines, and whether the Fusion Era will be governed under a more civilian frame than its predecessor was.