How do you make safe, cheap nuclear reactors? Bury them a mile deep

Startup Deep Fission has come up with a new way to deal with the economic and safety problems of nuclear power that is, to say the least, novel. The idea is to build a reactor that's under 30 inches (76 cm) wide and stick it down a mile-deep (1.6-km) drill shaft.

With its promise of limitless energy by breaking down matter itself, nuclear power has long held a utopian promise for humanity. However, economic and safety considerations, along with political opposition, have hindered its development – especially in the very countries that developed the technology.

The safety and economic factors are related because the high cost of building nuclear power stations has very little to do with the nuclear technology itself. Nuclear fuel, even with all the processing costs included, only comes to about US$1,663 per kilogram (2.2 lb). Because nuclear fuel has such an incredible energy density, that's about 0.46 ¢/kWh – and the fuel costs keep dropping as the technology becomes more efficient.

Where the real expense comes from is the massive civil engineering required to contain the nuclear reactor and protect the outside world in the event of a catastrophic accident. The reactor pressure vessel can be as much as eight ft (2.4 m) of stainless steel and the containment structure of reinforced concrete can be up to 6 ft (2 m) thick. Add in the foundations, support equipment, pressurizers, cooling systems, and the costs begin to add up before all the license fees are tacked on top.

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