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Comment by static_noise | Hacker News Reader

Does that mean you cannot use robots, nor can you use humans, to clean up this mess? What do you do then?

It means, that the robots have to be very "custom" build ones. With the intelligent parts beeing deposited outside of the dangerous area, communicating with the muscle via e.g. fibreoptics.

The robot consists ideally of some die-hard sensors positioned as far away as possible and as close as necessary - which are retractable mechanically in case of software failure by left behind elements. Then there is the actual tooling, which is basically just a remote controlled shell. A complicated setup, to say the least.

Imagine a Anemone with some little remote camera fishes on a tentacle, controlling a robotic crab on the longest tentacle of them all.

> the intelligent parts beeing [sic] deposited outside of the dangerous area

Is there a material that is transparent at optical frequencies but opaque at higher energies?

Ideally you'd want it to be gamma-transparent as well; otherwise, those gamma photons which hit it are going to deposit their energy into it. This is how glass viewing windows in nuclear materials processing facilities, for example, gradually cloud and embrittle over time, and have to be replaced. I'm not sure how well a relatively thin optical fiber would stand up, especially under the kind of bombardment we're talking about here.

Glass, but nothing stops neutrons.

You can stop them by slowing them down. Usually you'd use ellastic collisions with light atoms like hydrogen. Water works which is what reactors use. For shipping polyethylene is often used. Then some materials simply have a higher cross section for absorbing the slow ones. Had to look this up I saw boron and cadmium.

(Married to person who used to ship Californium-252)

You can use humans to clean the mess, whose massively redundant computational model is much more robust to radiation damage. They will however suffer or die from radiation exposure long term.

This is what was done at Chernobyl in admittedly much more dire situation. A quantity of Japanese remote-controlled robots were urgently imported back then as well, and failed in the same manner.

> You can use humans to clean the mess

Not this mess, or even that one, really. The "bio-robots", so called by their masters, were mainly collecting debris from the reactor explosion for containment; they were not trying to deal with the core slag sunk into the basement of the building, which at that time was still thermally very hot as well as being ferociously active. Even to approach that would have been immediately lethal.

Given the cited dose rate, the same is true at Fukushima - an acute dose of 10Sv is very likely lethal on its own, and at 650Sv/h you get more than that every minute. Anyone you send into that is going to be unable to work within seconds, and dead inside a couple of minutes tops.

The 'Elephant Foot' is 93Sv/h, and there is numerous footage of it filmed by human operators during containment efforts.

That's good to know, thanks. On the other hand, I find sources calling that dose rate lethal within minutes, and at least some of the Fukushima corium is roughly seven times as active. Even if you're willing to write off as many lives as it takes to reduce what is essentially solidified lava by means of hand tools into a containable form, I doubt it's likely to succeed simply because it'll kill off your workers so fast that, after a little while, no further progress is possible because of all the corpses blocking the way.

Well I mentioned it just as an example of humans being better at it than robots. I don't really imply that sending people to death is a good idea.

We should also distinguish between site cleanup (which is certainly impossible) and secure containment (which is possible and was done before). The idea is not to chip away bits of highly radioactive substance, but find a safe way around it to isolate the world from further contamination. Apparently, not everyone is convinced Japan has a plan there.

And of course it's what they did at:

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

https://www.nytimes.com/2017/01/28/us/troops-radioactive-isl...

Realize that the ostensible safety of nuclear energy is based on believing that black swan environmental and political events are impossible. Walk away from it and move heavily/quickly toward renewables.

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