One Company's Plan to Sink Nuclear Reactors Deep Underground

Long-time Slashdot reader jenningsthecat shared this article from IEEE Spectrum:

By dropping a nuclear reactor 1.6 kilometers (1 mile) underground, Deep Fission aims to use the weight of a billion tons of rock and water as a natural containment system comparable to concrete domes and cooling towers. With the fission reaction occurring far below the surface, steam can safely circulate in a closed loop to generate power.

The California-based startup announced in October that prospective customers had signed non-binding letters of intent for 12.5 gigawatts of power involving data center developers, industrial parks, and other (mostly undisclosed) strategic partners, with initial sites under consideration in Kansas, Texas, and Utah... The company says its modular approach allows multiple 15-megawatt reactors to be clustered on a single site: A block of 10 would total 150 MW, and Deep Fission claims that larger groupings could scale to 1.5 GW. Deep Fission claims that using geological depth as containment could make nuclear energy cheaper, safer, and deployable in months at a fraction of a conventional plant's footprint...

The company aims to finalize its reactor design and confirm the pilot site in the coming months. [Company founder Liz] Muller says the plan is to drill the borehole, lower the canister, load the fuel, and bring the reactor to criticality underground in 2026. Sites in Utah, Texas, and Kansas are among the leading candidates for the first commercial-scale projects, which could begin construction in 2027 or 2028, depending on the speed of DOE and NRC approvals. Deep Fission expects to start manufacturing components for the first unit in 2026 and does not anticipate major bottlenecks aside from typical long-lead items.



In short 'The same oil and gas drilling techniques that reliably reach kilometer-deep wells can be adapted to host nuclear reactors...' the article points out. Their design would also streamline construction, since 'Locating the reactors under a deep water column subjects them to roughly 160 atmospheres of pressure — the same conditions maintained inside a conventional nuclear reactor — which forms a natural seal to keep any radioactive coolant or steam contained at depth, preventing leaks from reaching the surface.'

Other interesting points from the article:

They plan on operating and controlling the reactor remotely from the surface.

Company founder Muller says if an earthquake ever disrupted the site, 'you seal it off at the bottom of the borehole, plug up the borehole, and you have your waste in safe disposal.'

For waste management, the company 'is eyeing deep geological disposal in the very borehole systems they deploy for their reactors.'

'The company claims it can cut overall costs by 70 to 80 percent compared with full-scale nuclear plants.'

'Among its competition are projects like TerraPower's Natrium, notes
the tech news site Hackaday, saying TerraPower's fast neutron reactors 'are already under construction and offer much more power per reactor, along with Natrium in particular also providing built-in grid-level storage.

'One thing is definitely for certain...' they add. 'The commercial power sector in the US has stopped being mind-numbingly boring.'

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