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Comment by himinlomax | Hacker News Reader

Re: nuclear waste

Deep core drilling seems to solve all the problems. Burying waste 3 km deep under 2 km of dirt makes it immune to even geological timescale movements. It also solves the problem of security; it's hard to see how a bad actor could drill a 2 km deep hole without being noticed.

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Aren't there experimental reactors that can "burn"/use the waste of traditional reactors?

Yes. I believe there are secondary and tertierary reactors that can handle the waste.

A fast reactor can burn the waste of thermal (traditional) reactor.

One design is the TWR

https://en.wikipedia.org/wiki/Traveling_wave_reactor

Still needs long term disposal in the end.

It's better than pumping your waste into the atmosphere for everyone to breathe.

Waaaay less waste is left in the end. Like, small enough to fit in a small room.

You still have to worry about it leaking into aquifers, though I believe that problem is already solved by encasing the waste in glass.

Are there really aquifers that move water ≥ 1km upward? I thought they were mostly lateral or downward moving.

Wells can be up to 200m deep. Aquifers are usually level, but the land above them might not be. So burying something 1k deep can leak into an aquifer that is drilled into elsewhere or even a high-table aquifer that drains into surface water downhill.

You will obviously notice any aquifer while drilling on the way down. And there may indeed well be water very deep down. But from what I understand, they are not connected with more surface level, and any diffusion of material takes a very long time. Keep in mind the pressure at those depths. Water is obviously lighter than rock, and if it had a way to go up, it would have.

That's supposedly not a problem at 2km. Keep in mind that the stuff would be packed under 2km of dirt.

The problem with drilling is, you have a bore hole connecting your cavern to the surface.

And the bad actor potentially does not care about being noticed.

>The problem with drilling is, you have a bore hole connecting your cavern to the surface.

Is that actually a problem? What kind of events could occur that would make it a problem?

>And the bad actor potentially does not care about being noticed.

Presumably this hypothetical hole in the ground would be in someplace like the US or Western Europe, under government control, and relatively heavily guarded. In that context, if a bad actor truly doesn't care about being noticed, we probably have bigger problems to worry about, like the collapse of modern civilization.

> Is that actually a problem? What kind of events could occur that would make it a problem?

Leckage

> Presumably this hypothetical hole in the ground would be in someplace like the US or Western Europe, under government control, and relatively heavily guarded.

I find your trust in the stability of the US or Western Europe for the next few hundred millennia surprising.

You don't need to worry about government stability when you bury stuff under 2km of dirt. Any group with the ability to drill that deep would have the means to do serious damage whether they do indeed drill or not.

We're talking about covering the stuff with a concrete plug, and then 2 km of dirt. There is no bore hole left. Drilling back in the same spot may be marginally easier than drilling the original hole, but it's still drilling a 2km hole.

Even better; drill into a subduction plate and have geology take your waste into the planet core.

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