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I really like what https://www.deepfission.com/ https://www.deepfission.com/ is trying to do. They have the absolute simplest model for nuclear fission that I c
by baron816 3mo ago
I really like what https://www.deepfission.com/ https://www.deepfission.com/ is trying to do. They have the absolute simplest model for nuclear fission that I can imagine. They’re digging one mile (1.6 km) holes dropping low enriched nuclear fuel to the bottom, and filling them with water. The pressure from the one mile column of water is perfect for the reactor. From there, it’s basically a geothermal well.
No need for an expensive containment dome, or expensive plumbing. If anything goes wrong, the nuclear fuel is already a mile underground. When the fuel is used up, they can leave it where it is since it’s below the water table. No need for expensive and hard to source highly enriched uranium.
The hard part is digging the wells, but that seems trivial compared to Quaise, who’s trying to dig 3-20km wells. The Deep Fission wells can just go anywhere (perhaps next to a disused former coal turbine?).
- rgmerk 3mo agoThat sounds like an absolute nightmare to get approvals for.
- irq-1 3mo agoThey got an executive order to ease the regulation... https://news.ycombinator.com/item?id=43911648 https://news.ycombinator.com/item?id=43911648
- simonebrunozzi 3mo agoQuite the opposite. They use proven reactor tech, and they are now going straight to commercial, vs other startups that need to go supercritical first.
- rcxdude 3mo agoI'm not sure that makes the approvals that much cheaper and easier. As I understand it, the slight differences between existing nuclear power plants that are for the most part the same design is already one of the reasons why they are so expensive to build.
- leonidasrup 3mo agoBuilding nuclear power plant underground could save significant costs, because the massive containment building is made from nuclear grade steel and nuclear grade concrete and is very expensive. But you need a low cost excavation technology. https://ifp.org/nuclear-power-plant-construction-costs/ https://ifp.org/nuclear-power-plant-construction-costs/ "Nuclear-grade components don’t necessarily have higher performance requirements than conventional components. Reinforcing steel in nuclear-grade concrete, for instance, is the same material used in conventional concrete. Instead, the additional cost often comes from the additional documentation and testing required. Documentation requirements also increase costs indirectly, by reducing market competition among manufacturers. Because these requirements are difficult for manufacturers to implement, many simply don’t bother to manufacture nuclear-grade components." "Sources of Cost Overrun in Nuclear Power Plant Construction Call for a New Approach to Engineering Design" https://www.sciencedirect.com/science/article/pii/S254243512030458X https://www.sciencedirect.com/science/article/pii/S254243512... "Similarly, while our analysis identifies the rebar density in reinforced concrete as the most influential variable for cost decrease, changes to the amount and composition of containment concrete are constrained by safety regulations, most notably the requirement for containment structures to withstand commercial aircraft impacts. New plant designs with underground (embedded) reactors could allow for thinner containment walls. However, these designs are still under development and pose the risk of high excavation costs in areas or at sites with low productivity."
- noja 3mo agoWhat are the side-effects of regularly detonating nuclear bombs at that depth?
- throawayonthe 3mo agohttps://en.wikipedia.org/wiki/Underground_nuclear_weapons_testing https://en.wikipedia.org/wiki/Underground_nuclear_weapons_te... seems it usually happened at lesser depths, and for ones deep enough to contain debris, the main effects were geological, from the actual explosion? not what i expected tbh
- rcxdude 3mo agoI'm not sure how this question would be relevant. Nuclear bombs are impractical for power generation and a nuclear reactor is not ever going to turn into a nuclear bomb.
- leonidasrup 3mo ago"Project PACER, carried out at Los Alamos National Laboratory (LANL) in the mid-1970s, explored the possibility of a fusion power system that would involve exploding small hydrogen bombs" https://en.wikipedia.org/wiki/Project_PACER https://en.wikipedia.org/wiki/Project_PACER
- notrustincloud 3mo agobelow and penetrating the water table with the potential for short and long half-life transuranic fissile products and a path of least resistance for any runaway conditions which is directly to an uncontained well head... with the extra bonus of installation proposed in 'spent' hydrocarbon bearing regions which implies reduced density substrates with all the tiny seismic outcomes and risks. perfectly safe /s
- cyberax 3mo agoWe can then build a primary school on top! And use the water from the well for heating directly. What could possibly go wrong!?!?
- stavros 3mo ago[flagged]
- Ma8ee 3mo agoWe don’t need any new and untested technology to solve to stop spewing out greenhouse gases. We just need to scale up current green tech. It’s not know how and technology that is lacking, it is political will.
- stavros 3mo ago"We don't need to research any more potential solutions to this existential problem we're facing" is certainly a take.
- Ma8ee 3mo agoI don't say we shouldn't do research. What I do say is that we do have all the technology we need. And more importantly, we don't have the time to wait for some future technology that potentially could solve all our problems. The climate disaster has already started (and this [0] is not "the new normal", this is just the beginning, a hint of what we should expect). The only reason we are in this shithole is because of the lack of political will. It would have been comparable trivial to solve if we just had started 30 years ago when scientists started to yell about that it was getting urgent. [0] https://www.theguardian.com/world/live/2026/jun/24/europe-heatwave-live-news-updates-uk-record-breaking-temperatures-italy-red-alert https://www.theguardian.com/world/live/2026/jun/24/europe-he...
- cyberax 3mo agoIt's an extremely stupid idea. Your whole water column is going to be contaminated with fission products. And you won't be able to get any reasonable amount of power out of that contraption. And even if you are stupid enough to actually do this, the fuel efficiency will be terrible. Your only negative feedback for fission is the Doppler effect and thermal expansion. So you will only be able to utilize a tiny percentage of the fissionable materials.
- rcxdude 3mo agoWould the fuel efficiency be sufficiently bad to make the fuel costs relevant to the cost of running the plant, though?
- cyberax 3mo agoYes, it would. Fuel is around 2-4% of the total costs for a regular nuclear power plant, but that's because regular reactors can burn it deeply. This reactor will only burn a couple of percents of the available fuel, so the fuel costs will probably be around 10-20 times higher. BTW, this tradeoff can be acceptable for some very specific applications. Kilopower ( https://en.wikipedia.org/wiki/Kilopower https://en.wikipedia.org/wiki/Kilopower ) is designed to use passive regulation.
- UltraSane 3mo agoThe water column is isolated fron the fuel. The weight of the water column just allows for a cheaper enclosure. https://www.nrc.gov/docs/ML2419/ML24191A372.pdf https://www.nrc.gov/docs/ML2419/ML24191A372.pdf
- tonyedgecombe 3mo agoPresumably once you are finished with it you could just fill it with concrete. Or partially fill it and drop another reactor on top. The only projects that overrun more than nuclear is nuclear waste disposal. This kills two birds with one stone.
- cyberax 3mo ago
- trashb 3mo agoCreate a small sun a mile under the ground, what could go wrong? Also the actual article it seems has nothing to do with fission, they are focusing on extracting the heat already down there. "superhot rock needed for next-generation geothermal power"
- da-x 3mo agoThe sun performs fusion, not fission.
- leonidasrup 3mo agoThere many kinds of geothermal power and if you don't have access to hot fluids found naturally in basement rock, you have use hot dry rock geothermal energy. https://en.wikipedia.org/wiki/Hot_dry_rock_geothermal_energy https://en.wikipedia.org/wiki/Hot_dry_rock_geothermal_energy Here the biggest obstacle to economy of the geothermal power is the very low heat conductivity of rock. "The conductive heat flux averages 0.1 MW/km2. These values are much higher near tectonic plate boundaries where the crust is thinner. They may be further augmented by combinations of fluid circulation, either through magma conduits, hot springs, hydrothermal circulation. " https://en.wikipedia.org/wiki/Geothermal_energy#Resources https://en.wikipedia.org/wiki/Geothermal_energy#Resources For comparison: Thus the solar energy arriving at the surface with the sun directly overhead can vary from 550 MW/km2 with cirrus clouds to 1025 MW/km2 with a clear sky https://en.wikipedia.org/wiki/Solar_constant https://en.wikipedia.org/wiki/Solar_constant
- noduerme 3mo agoI'm sorry, I've worked in advertising for much of my life, and I just can't get past the top line "Advanced Nuclear for the AI Era". That reads as an extremely desperate or opportunistic marketing pitch to me. Kind of like when you get a brochure for a condo in a high rise that will never be built...except even more shameless?
- veltas 3mo agoProbably because AI datacenters would benefit from tech like that.
- mjhay 3mo agoThey kind of have to shoehorn “AI” in there have any hope of raising capital these days.
- hyperbovine 3mo agoI think it’s a nod to the idea that AI is set to boil off the oceans unless some seriously novel ideas about power generation take hold.
- deleted 3mo ago[deleted]
- Someone 3mo ago> They’re digging one mile (1.6 km) holes dropping low enriched nuclear fuel to the bottom, and filling them with water. > When the fuel is used up, they can leave it where it is since it’s below the water table. To do both, they’ll have to guarantee that that column of water stays isolated from groundwater for a long time after the fuel is used up. Reading https://www.deepfission.com/faq https://www.deepfission.com/faq, they answer that question with “Importantly, the mile-deep column of water in the borehole is expected to provide the pressure conditions required for safe reactor operation. Water within the borehole is also intended to contribute to the reactor’s thermal management system”. So, what do they do if their drill hole starts leaking, and they lose pressure? and “Our boreholes are expected to be lined with multiple layers of casing, including steel casing and concrete intended to maintain structural integrity and isolate surrounding geological formations” I don’t think those are good answers. They say what they want to do, but almost nothing about how they’ll do that, and try to avoid making hard statements on the what by using “is expected” and “is intended”.
- cucumber3732842 3mo ago>I don’t think those are good answers. Steel and concrete are what we use above ground so..... >They say what they want to do, but almost nothing about how they’ll do that, and try to avoid making hard statements on the what by using “is expected” and “is intended”. They say nothing about how because those are trivial problems in the well (and oil) drilling industry.
- AnimalMuppet 3mo agoWe use steel and concrete. We don't usually expect them to last 10,000 years, though.
- bronson 3mo ago> those are trivial problems in the well (and oil) drilling industry. Ah yes, an industry well known for its adherence to safety standards and never having surprising blowouts.
- Asooka 3mo ago
- mentalgear 3mo agoThis echoes 'safe fracking' claims - and now many people in proximity have gas coming out of their facets. Digging hazardous materials out of sight into a potentially unstable or potentially becoming leaky structure is never a sound strategy.
- Dibby053 3mo ago>They have the absolute simplest model for nuclear fission that I can imagine Agree. What I don't understand is: why has it never been done before? They can't possibly be the first to come up with this idea, which doesn't seem to rely on any novel technology.
- deleted 3mo ago[deleted]