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Comment by ajross | Hacker News Reader

(Edit: seems like everyone is reading this as an argument against nuclear power in the abstract, and skipping the second paragraph. Come on people. You can be OK with large defensible reactors and still think that dropping a 5MW reactor into a random ass residential neighborhood is dumb as shit. Dangerous stuff is dangerous. Be careful with it and use it judiciously.)

As it should. A reactor core is just trivially the most poisonous single object humanity has invented. And by definition it's a operated by controlling a chain reaction that can by its very nature lead to excursions.

And the benefit here is a 1-5MW generator, the same market served by existing largely portable diesel generators.

Seems like a cost/benefit analysis might have a lot to say here. Maybe spacecraft might be a better fit, but... a portable generator? I don't see the need, personally.

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> And by definition it's a operated by controlling a chain reaction that can by its very nature lead to excursions.

When nuclear reactors leak poison gas then something has gone wrong, and it makes international headlines.

Diesel generators are designed to leak poison gas; hundreds of millions of them do this every day.

I don't think you can really compare the poisonous emissions of diesel exhaust leaked materials from a reactor.

I see your point, any nuclear excursion tends to get blown out of proportion, but it does have some unique dangers.

In particular, diesel fumes eventually dissipate, whereas radioactive materials will settle and continue to be a problem for decades. Which may not be a problem if it's left alone, but anyone unlucky enough to interact with it could end up with it on their body/clothing unaware that they're absorbing an unsafe dose over a period of days or weeks.

But yes, I agree, we do need to move away from fossil fuel sources one way or another.

Diesel fumes will dissipate locally, but they will cause Global Climate Change that threatens to destroy human civilization as we know it.

Meanwhile, radioactive toxic stuff will remain toxic locally.

I mean, you're not wrong. I'm just thinking that the larger nuclear plants are a safer than deploying many small reactors

I don't think you can really compare the poisonous emissions of diesel exhaust leaked materials from a reactor.

Sure you can, you just need to agree on the comparison criteria, like, for example, the total number of illnesses/death from normal (and predicted abnormal) operation of the device. Burning fossil fuels still leads to deaths even if they are spread over a large area and/or time.

I am afraid I don't have the numbers to back up my claim but when I was at university, my thermodynamics lecturer showed us a calculation that background dose from radioactive material at a coal powered fire station is higher than that of a nuclear power station. This is because of the shear amount of coal power stations burn through, and in that fuel, there is a trace amount of radioactive material that eventually gets out into the atmosphere.

I've previously worked on a nuclear licenced site and we were not even allowed to throw smoke alarms in the general rubbish due to there being radioactive material inside.

Yes, absolutely! Coal is pretty much the worst of the worst.

My concerns are solely with how fuel would be managed, so that it isn't lost, and subsequently broken. One example was scrap workers taking a radioactive source to a scrap yard to be melted down, not realizing what it was.

There is a lot of much deadlier chemicals in the factory near your city, only there is no Greenpeace et. al. crowd chanting how all those chemicals with long, complicated names are dangerous, since they spent all their efforts fighting nuclear energy (for good 50 years).

Thanks to that we are where we are.

> There is a lot of much deadlier chemicals in the factory near your city

Examples at a concentration as dangerous as a reactor melting down?

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

Hell, https://en.wikipedia.org/wiki/Great_Molasses_Flood killed more than the Fukushima Daiichi meltdown.

Fun fact, Bhopal was so egregiously horrible, that it is what led to the create of the CSB (Chemical Safety Board). A lot of their investigation videos are on youtube, and absolutely worth watching

I went down that YouTube rabbit hole too, the production value is some of the best I've ever seen from any government department.

presumably https://www.youtube.com/user/USCSB ?

Modern reactor designs do not melt down.

This is simply not true. A sustained nuclear chain reaction just needs to be physically reconfigured a bit to produce a reaction excursion. It's true that modern designs have made good progress in things like intervention-free failsafes that make such reconfigurations much less likely. It's simply not possible eliminate the possibility entirely.

And in any case, this is a piece of military hardware which might plausibly be "reconfigured" be being struck by a rocket. It's not a civilian reactor inside a secure facility.

Your statement is analogous to saying "charcoal grills do not start forest fires". Used correctly, they certainly shouldn't. But they sure as hell can if you kick them over on a dry summer day. Same deal here.

What the above poster is probably referring to are reactor designs that are passively safe. Like using lithium as a coolant and moderator. As the reactor heats up the lithium's density drops, which in turn reduces the rate of the nuclear reaction. It creates a stable equilibrium. The reaction would also stop if the lithium were drained - there would be no more moderator to sustain the nuclear reaction.

> reactor designs that are passively safe

To be glib: Not vs. fucking rockets they aren't. Those designs imagine that the fuel doesn't move and that the coolant is the medium of failure.

What happens when you move the fuel?

Even if a meltdown doesn't happen, if such a generator is struck by, for example, an artillery shell, who is going to clean up the mess?

> What happens when you move the fuel?

It stops reacting. If you blow up a nuclear reactor you've made a nice radiological hazard (though Uranium/Thorium themselves aren't particularly hazardous), but as soon as the fuel stops being contained inside of the appropriate neutron-mediating environment and is scattered, it will become subcritical.

The question of whether or not deploying nuclear reactors in warzones is a good idea is entirely different from the question of whether meltdowns are a realistic possibility. A critical nuclear reaction can be sustained with neutron reflectors and moderators using an amount of fuel that would otherwise be subcritical. Any "reconfiguration" only reduces the criticality factor of such a reactor.

Then the reaction stops because it's no longer in the presence of a moderator.

Hydrogen cyanide and phosgene both are extremely popular, mass produced industrial chemicals that have been used as chemical weapons.

Not PFAS though.

It was produced for the benefit of all mankind.

And now that's whose bloodstream it can be found in.

Mainly for two reasons, it's half-life is longer than the lifespan of living things, and people spread it around like they never should have done at all.

That makes it analogous to opening Pandora's box more so than all kinds of dangerous things.

> diesel generators

Poisoning us on the long term, and worse - starting a runaway greenhouse heating process which will make the planet uninhabitable in just a few hundred years.

Portable/temporary generators are vanishing fraction of global energy generation, and you know that. If we actually care about that last 0.001% or whatever, we can run them on biodiesel.

Large portable diesel generators that operate with that kind of power in 24/7 operation is very dirty, costly, nosily, and require continuously transporting of fuel. You do not want that near a hospital unless it is an emergency (short duration) or the life lost to the pollution is preferable compared to not having a hospital with power. The design parameters for those portable nuclear reactors is to not having to refuel, and being able to use it in places where pollution is not acceptable.

Uh... there are many hospitals with deployed diesel backup generators already. It's sort of the standard solution in the space, in fact.

Again, no one seems to be understanding the context here and just wants to jump in with knee-jerk pro-nuclear arguments. The application under discussion is a portable generator to be deployed locally as backup power in presumably-chaotic emergency situations. That is simply not where you want a reactor, period.

Backup generators operate during short intervals, not 24/7 for years. Even the pollution created during backup testing runs get documented and is a real point of concern for hospitals. The benefit however of having consistent power outweigh the drawback of temporary pollution.

I don't understand this knee-jerk pro-fossil fuel arguments, using your words. Fossil fuels, especially those in backup generators, are very harmful if run long term. We are currently in a pandemic where one of the primary causes of death is the inability to take up oxygen, and in this context we want to add air pollution?

> Nuclear power is “orders of magnitude more energy dense than any other known technology,” Waksman told National Defense. “That allows the possibility to provide resilient power for years and years, without needing to refuel. … Refueling can be a real burden in remote areas.”

Maybe spacecraft might be a better fit, but... a portable generator? I don't see the need, personally

I'm not sure I understand how you're concerned about a portable nuclear generator failure or attack releasing nuclear materials, but you suggest that it would be somehow safer (?) to strap it on top of hundreds of tons of explosive rocket fuel and launch it into the sky?

Arrgh. This is misunderstanding the argument in the OTHER direction.

Cost/benefit analysis isn't about deciding what's "safer" in an absolute sense. It's about how much you get for how much risk you're willing to accept. The risk of one meltdown is real, but not impossible to tolerate in all circumstances.

Is it worth keep a bunch of these reactors around to deploying to urban Mogadishu or wherever to supply an invading military force with power? I argue not. The risk is high, and electricity is cheaply available already.

Is it worth launching one reactor into space if it enables an entirely new capability in solar system exploration? Maybe yes. It's just one launch, you can do it in remote areas. The people directly involved can be made aware of the risks (and are taking significant risks already). I don't have a full whitepaper to hand you on this but my intuition says that this might be OK, yeah.

Air pollution in France is responsible for more than 40 thousands deaths every year. Nuclear power, well, Chernobyl in total is estimated at around 10 thousands deaths total. In France it's actually 0 since the radioactive cloud stopped at the border /s.

This is a portable reactor for use by the army.

So the question is what would you rather be hit by a missile? A nuclear reactor or a diesel engine?

The emissions of a diesel engine are irrelevant here because that's a specific use-case that is going to be negligible compared to emissions by cars and industry in general (or even by the army).

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