Deep Fission To Build Nuclear Power Plants Below The Surface Of The Earth

Sign up for CleanTechnica’s Weekly Substack for Zach and Scott’s in-depth analyses and high level summaries, sign up for our daily newsletter, and/or follow us on Google News!

Nuclear energy — the dream that will not die. Ever since Jules Verne tantalized readers with his nuclear-powered submarine, the idea that splitting atoms could one day power all of civilization has held humans in thrall for over a century. That’s despite some unfortunate setbacks such as Chernobyl, Three Mile Island, and Fukushima. Hollywood didn’t help things with its fanciful China Syndrome movie, which was based on the notion that a nuclear reactor that suffered a meltdown would be so hot, it would burn a hole in the Earth that would go all the way through the core of the planet and keep going until it reached China.

I am not a nuclear scientist, nor have I ever played one on TV, but I have always had strong skepticism about the benefits of nuclear power. They start with the age old question of what to do with nuclear waste that has a half life measured in millennia. Proponents like to brush aside such concerns as if they were mere annoyances, but they never seem to actually address the issue.

Over the years, there have been suggestions they could be buried in concrete vaults deep underground in Yucca Mountain or dumped into the deepest parts of the ocean. The primary justification seems to be the “out of sight, out of mind” principle. Perhaps I have watched to many Jacques Cousteau episodes, but the idea of using the oceans as toilets just feels wrong to me.

Other concerns I have center on the long history of nuclear power plants costing many times more than originally planned, placing burdens on rate payers for decades. We seldom hear of massive cost overruns for solar or wind farms, so why do we need nuclear systems that we know in advance will cost far more than projected? One last thing. Nuclear power plants require vast quantities of concrete. While I love concrete — the building I live in is made from it — it is one of the largest sources of carbon dioxide emissions in the world. That makes the claims made by nuclear advocates about how “green” nuclear power is a little suspect in my mind.

Deep Fission is the latest venture to come up with a new way to finally make nuclear energy safe and abundant. It proposes to bury 15 MW nuclear power plants one mile below the surface of the Earth. In its website, it says, “The future of nuclear will be boring.” Clever.

Here’s more:

“The growing global demand for clean energy, accelerated by the AI boom, is challenged by power outages, climate change, and a slow transition away from fossil fuels and coal. The result has been unprecedented public support of nuclear energy — a clean source of electricity without the carbon footprint. Unfortunately, surface level nuclear power plants often face unforeseen construction costs and delays due to a majority of the budget addressing containment and safety issues.

“At Deep Fission, our technology team realized that by taking existing [pressurized water reactor] technology and placing it down 30-inch boreholes a mile underground, our customers will benefit from the natural containment and safety features a mile of rock atop our small modular reactor can provide naturally. By removing surface construction costs dramatically without sacrificing safety, we also cut the timeline to an operational power plant significantly.

“One Deep Fission reactor only needs a 30 inch borehole for in-depth placement, producing 15 MW of energy one mile underground. Ten Deep Fission reactors need only a ¼ of a square acre to yield 150 MWe, while less than three square acres can house 100 Deep Fission reactors to generate 1.5 GWe. Our reactors are fully modular, allowing customers to order multiple reactors in discreet bespoke configurations to meet the diverse needs of its end-users in large cities, or military bases or to power hyper-scale data centers and utilities.”

A New Take On Nuclear Power

Elizabeth Muller, CEO of Deep Fission, told Anthropocene Magazine, “We’re able to draw on work that’s been done by the oil and gas industry to drill holes a mile, two miles, four miles deep. If you’re in a borehole a mile underground, you have the exact conditions to create a pressurized water reactor without the construction costs, which are 80% of the cost of current nuclear plants.” Deep Fission’s micro-reactor is an extraordinary shape. Picture something as narrow as a garbage can and as tall as a house, Anthropocene says.

In a pressurized water reactor, a technology that is used in about two thirds of all nuclear reactors worldwide, the heat created by splitting uranium atoms is absorbed in water pressurized to about 150 atmospheres, which keeps it in a liquid state even at high temperatures. The superheated water, which is now slightly radioactive, flows out of the reactor and is used to boil clean water in another part of the plant. That steam from that boiling water then drives turbines to generate electricity.

Deep Fission plans to put just the dirty, dangerous parts of a PWR — the uranium fuel and most of the radioactive water — deep underground. The process of creating steam to turn generators will take place on the surface. In a hole a mile deep, the weight of the water alone equals about 150 atmospheres of pressure at the reactor, which should allow Deep Fission to use some already proven and licensed PWR technologies without having to create such high pressure artificially. “Uranium fuel is not that expensive,” says Muller. “What makes nuclear power so expensive is all the concrete and steel that goes into building the pressure, and then the containment in case anything goes wrong.”

Putting the active reactor so far underground means that safety should be much less of an issue. Deep Fission calculates that there would be ten billion tons of rock shielding between the reactor and the surface. That means the underground part of the system would be safe from tornadoes, tsunamis, airplane crashes, or deliberate attack, says Muller. “Even for earthquakes, a mile underground, you could have some shaking, but you’re not going to have the same potential for things toppling over.” The possibility of volcanic activity is not considered significant, apparently, and we can presume that doing this along the San Andreas fault is pretty much out of the question.

Deep Nuclear Versus Deep Geothermal

Some CleanTechnica readers may wonder why we need subterranean nukes when the heat of the Earth itself a mile below the surface is already hot enough to boil water to make steam to turn generators. Adam Stein, director of the Nuclear Energy Innovation program at the Breakthrough Institute, told Anthropocene that the Deep Fission design has some things in common with advanced geothermal power generation from companies like Fervo Energy. The nuclear reactors Deep Fission plan to use will create much hotter water and thus more electricity, but drilling a hole 30 inches wide will be exponentially more expensive than the much smaller holes Fervo Energy requires.

“Most oil and gas wells are much narrower, in the 4 to 8 inches range, “ says Muller. “But 30 inches is well within the ‘we’ve done this before’ capability. We’ve gotten solid quotes on how long it’s going to take to drill these holes and we’re talking about a couple of weeks.”

Deep Fission Still Has A Waste Problem

Spent uranium fuel is piling up at nuclear power plants around the world, but Deep Fission thinks its technology may offer a solution. The Deep Fission micro-reactors would need refueling about every two years, and the spent fuel will be highly radioactive for thousands of years. In 1987, the US Congress selected Yucca Mountain in Nevada as the long term, geological repository for much of America’s nuclear waste. Sustained opposition from local politicians has left that project more or less permanently stalled. “Right now we’re in a deadlock until Congress moves forward with some solution,” says Stein. “It is likely that we will, if not this year, then in the next few years, see some progress in a direction. It’s just hard to tell what direction that will be.”

The option Deep Fission prefers is to simply lower its reactors’ waste deeper into the very same boreholes. That would have the advantage of never transporting waste by road, rail or air, with all the attendant risks of spillage, accidents, or hijacking. “And once we’ve done it for Deep Fission, I think it also paves the way for other people to understand how great boreholes are for nuclear waste disposal,” says Muller. “Hopefully, this will unlock the solving of the nuclear waste problem.” In fact, Deep Fission has a sister company called Deep Isolation that intends to make a business out of burying nuclear waste deep underground.

And so, we are back where we started, with a bold new technology that promised to finally solve the technical and cost issues associated with nuclear energy. Does anyone but me get queasy at the thought of stuffing nuclear waste deep underground? Do we really know what goes on down there, enough to know what we put there will stay there and not gravitate to other places where we don’t want it to go?

Again and again, humans think they can ignore the consequences of their waste products. Instead of making electricity from sunlight or wind, which have virtually no waste products, let’s revive coal power and then use more energy to suck the crud left behind out of the atmosphere and bury it deep underground. Not only that, there’s a lot of good stuff in coal ash, if we can recover it before it leaches into our ground water.

Why Nukes?

There are those for whom nuclear power is a religion. They will not rest until they have unlocked the secrets of the sun and made them serve the needs of humanity. And yet all around us are non-polluting sources of energy. All we have to do is harvest it and distribute it efficiently. Humans insist on sowing the seeds of their own destruction, even when alternatives are staring them in the face.

Would you want to live near an enclave of nuclear power plants buried a mile beneath your feet? If not, we will need to build new transmission lines that many communities oppose. This seems like a pie in the sky, Buck Rogers-type fantasy that will take precious time and resources away from what we know works and produces electricity that is almost too cheap to meter. Deep Fission blithely insists there is nothing to worry about and that burying nuclear power stations underground is perfectly safe, but a quick poll in the CleanTechnica breakroom showed many of us are not convinced.