Millimeter wave technology drills 100 meters into granite

> 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, 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”.

I'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?

Create 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"

It'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.

That sounds like an absolute nightmare to get approvals for.

This 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.

>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.

below 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

What are the side-effects of regularly detonating nuclear bombs at that depth?

You don't need a significant flow of argon, just enough to keep unwanted gasses out of the waveguide.

It's possible there exists a material that is transparent to mm waves, airtight, and can survive the conditions at the bottom of the hole. In such a case they could cap the waveguide and prevent any gas leakage.

I'm quite sure Quaise is well aware that Argon isn't cheap and are already exploring multiple avenues for reducing its usage.

It is interesting that they have to use Argon instead of the more typical Nitrogen or SF6. A waveguide with such a significant pressure differential is decidedly unusual and a unique challenger for what they are doing.

There is definitely an economic changeover point, I’m sure I read they will use conventional drilling down to a certain depth, before switching to MMW

I doubt argon is the purge gas.

You mean the argon gas used as medium specifically? I assume the purge gas is something else, cheaper?

Why mmwave instead of ultrasonic? FWIU 28 kHz shreds the quartzite in granite?

Naively, I wonder how much the density of argon gas helps here, in terms of being able to recover and reuse the argon gas in a relatively closed-loop system.

> There should be useful tools, such as small units for drilling pipe holes through concrete and rock.

We already have cheap and effective mechanical drills capable of these tasks, and it's unlikely a brand new technology can compete with those on cost.

Unlike in the actual design niche, where mechanical tools are infeasible due to the temperatures involved.

For shorter holes traditional mechanical methods work just fine. If you are going to build a giant excavator you don't waste time making shovels for gardeners. The problem drilling deep into ground is that the power source on the surface of earth and drill bit deep underground are connected by long floppy noodle while the hole is getting crushed from the sides by bunch of elephants. It is difficult to transfer rotation from the motor/power source at the top to the boring head, and reinforce the walls to prevent them from collapsing, having whole thing heated to few hundred ℃ doesn't make it easier on hardware.

In case of something like underground tunnels these problems are avoided by having hole big enough to fit the drilling machine as well as all the equipment and crew to reinforce the walls with concrete.

The fact that people have made a way to drill few hundred to few km using mechanical means is already an engineering marvel. In the context of everyday manufacturing beyond the hole depth to diameter ratio of 5:1 things already start to get more complicated. With more specialized techniques you might get 10:1 - 100:1. A bit easier for softer materials like wood or if you don't care about precision. But for deep underground drilling we are talking about ratio of thousands to 1.

It's not like they are not making tests at shorter depths. Once technology is sufficiently developed it might also trickle down to some shorter few km holes if geological conditions are right. Although probably never for something like few dozen meter water wells or making a hole in concrete at construction site. Not sure how well it works in soft dirt. Who knows about distant future, we now have relatively cheap desktop laser cutters, laser pointers, measuring equipment, microwave ovens, but those were not the initial products when developing those technologies. On the other hand some tech like wire EDM has remained niche manufacturing technology, even though modern electronics and software could allow making it much cheaper.

Except that it is not a laser but a high power radio transmitter made with a vacuum tube (gyrotron).

For generating the highest possible power of radio waves, vacuum tubes remain the only solution.

This drilling method resembles more a microwave oven (which uses a magnetron), than a laser.

Looks to me like the author wrote themselves an inline note and forgot to remove it before publishing.

Gyrotron isn't quite a maser, more akin to a free-electron (i.e. electron beam) RF source. AFAIR (might be wrong, but based on what I could find there: https://www.thinkgeoenergy.com/wp-content/uploads/2021/03/mi...) they aren't literally vaporizing the rock, rather locally heating it til it crushes into particles that can be blown away.

They mentioned about 1 hour per meter at 1 MW.

I think we can use 1 Gulf War for units

Or a hectometerstone, if you will

It turns it into granite cotton candy.