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Comment by choeger | Hacker News Reader

How long does it take to dig a hole to the mantle? Could we drop nuclear waste in such a hole?

I think you inspired the other front page story lol

You absolutely can, and probably should if your intent is to go really, really deep — sort of a "nuclear jackhammer". The usual concerns are a little bit shifted in that context, you're likely to explode your stuff into billions of tons of e.g. mercury (some heavier-than-earth compound) to help with extraction of dirt... good times in perspective.

Have fun with it, https://youtu.be/jZQP2oNDkAM?t=525 (he talks specifically about nukes at 8:45, but I really recommend watching the whole if you're into this kind of 'crazy-but-great' ideas. ;-)

I don't think heating up nuclear waste would be a good idea. Even if you don't reach the mantle, it's hundreds of degrees (celsius) down there already.

That said, putting nuclear waste deep underground and sealing the hole is probably the best best.

We already have deep spaces underground for storing nuclear waste. We don’t, however, have a way to transport said waste to said holes.

Nuclear waste is already used to being hot in the reactor core (way hotter than the temperatures in the article), and are still hot after removal from a reactor. That's why spent rods are put into a cooling pool for a year or more after removal from a core.

Still, the idea of dumping waste that deep doesn't sound like a good one.

The concept is described here

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

But the article sounds like a sales pitch

It tracks that I would not be the first person to think of this, but long term nuclear "waste" storage came to my mind immediately when I read the article.

Really dumb question, but can spent nuclear rods still be used to generate electricity (from the heat)?

Thanks

Not a dumb question. With your parenthetical, "from the heat", no. A crude measure of "potential electrical energy" is the difference in "temperature" (really, enthalpy) between the coldest water coming in contact with the spent fuel at the bottom and hottest water/steam leaving the top (natural convection), and while each rod's heat generation is significant enough to require water cooling so it doesn't melt, it isn't enough heat in enough time to generate enough steam to move a X00 MW turbine or two.

Cool, thanks for answering!

I would like to argue that waiting for partitioning and transmutation technology to mature and temporarily storing the waste until then makes more sense than putting nuclear waste into a place where we can not easily (or at all!) reach it when we can use it (and thereby actually solve the problem).

Some half-lifes are so long that just any progress over a fraction of these time-scales should be be enough to be better off to wait for the tech to be ready than to bury the material.

"temporarily storing the waste" is mostly what the US have done since the late 70s. https://en.wikipedia.org/wiki/Dry_cask_storage#United_States

Yucca Mountain was supposed to be the solution this temporary storage; but the budget for Yucca Mountain got suspended, so the US are back to the temporary solution.

But postponing forever in the hope of a better solution is a bad solution; because in the meantime they are in unsafe locations.

Not forever, just for 200-500 years.

Transmutation technology is inherently more dangerous than simple uran fission plants due to the problem of proliferation. A lot of nasty stuff, e.g., weapon-grade Plutonium, be cooked up in these transmutation plants on demand, AFAIK.

What could possibly go wrong...

There's a movie about that...

https://www.imdb.com/title/tt0059065/

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