Boom!
Small nuclear reactors: tiny NuScale reactor gets safety approval
461–470 of 554 posts
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#462Earlier quoted context omitted.
It’s not bad faith or disingenuous. Fukushima happened because of an earthquake, remember?
An earthquake that was one of the largest ever recorded and resulting in one of the largest tsunamis ever as well. So you know, pretty common circumstances.
That the '1000 year tsunami' happened 40 years after commissioning is more suggestive of engineering incompetence than bad luck. And unlike bad luck, incompetence is a lot more prevalent.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#463Earlier quoted context omitted.
Anything that knocks a fully functional multiple thousands of tonnes of concrete, steel, water and fissile material onto it's side was already going to fuck up your day. As far as I'm aware we've never had a nuclear reactor go sideways, and it's kinda ludicrous to even ask. It's one of the most massive structures, built on bedrock because it's too heavy to be built on anything else, and even these "small" reactors wi…
They are vertical cylinders to be suspended vertically in a pool of water, not massive squat objects sitting on bedrock. They are thin and relatively top-heavy. It is not ludicrous to ask what could happen should they not remain as vertical as designed. From a planning perspective, if verticality is a requirement then that verticality has to be protected as strongly as any other aspect. Any attachment or mounting poi…
I was assuming they'd bury these.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#464If you have 20 minutes, the video linked in the comments of the earlier HN post is quite informative, giving a much better technical explanation than the original article: https://www.youtube.com/watch?v=7gtog_gOaGQ
It is fascinating, for example, how a slight change in the packaging of the fuel (as sand-sized pellets coated with carbon) affects the safety/stability of the design, and how resonances in the cross section for neutron absorption come into play (they broaden at higher temperatures, dampening rather than enhancing the overall reaction speed, as temperatures rise).
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#465Can someone refresh my memory? Is generating electricity directly from the products of fission proven [mathematically] to be less efficient than decay->steam->mechanical->electrical or is just that the applied science of steam power is so far ahead of everything else? My peace of mind would be much greater if the energy transfer went through solid state systems instead of a working fluid that is pretty good at carryi…
Has there even been a case of the steam being problematic?
Most of the time? Isn’t that why everyone was pushing for molten salt or pebble reactors?
I was going to say coincidence but this was clearly Google doing creepy stalker things after it saw what else I was searching for on the Internet (even not using google.com) This popped into recommendations an hour after you asked:
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#466Earlier quoted context omitted.
> The other reason we don't do it is that it is just cheaper to buy more Uranium than setup reprocessing plants Is it cheaper to buy more Uranium and deal with the so-far-and-growing half-trillion dollar cleanup liability than to set up and operate reprocessing plants? Of course I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it.
> I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it. I was talking to an environmental scientist that other day who was lamenting that the liability for solar panel waste was being treated as "tomorrow's problem", and no one in power cares about it. If we factor in the tomorrow problem nuclear looks even better, because we have a chance of being able to de…
You should inform that environmental scientist that Veolia in France has a pilot facility that can recycle 95% of the materials recovered from retired solar panels. The other 5% can be used as feedstock for asphalt aggregate.
Keep in mind, panel longevity is upwards of 25-30 years, at which point they'll still be producing 80-90% of their rated output. Inverters (single or micro) can be recycled in traditional electronics recycling processes.
https://www.veolia.com/en/newsroom/news/recycling-photovolta...
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#467Earlier quoted context omitted.
What's the radius around a reactor where a critical core can trigger fission in the next reactor over?
You'd have to place both cores within the same reactor pressure vessel, which isn't possible.
So as long as the reactor vessel is intact it absorbs 100% of the neutrons? Going out as well as coming in?
Because in a failure you’ll have only one pressure vessel between the two cores. If everything else goes right.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#468Earlier quoted context omitted.
I like your optimism, people would just live in inhabitable places or relocate and would be welcome, such gentlemen. I expect WWIII.
What specifically is going to cause mass migrations in your mind, and on what time scale? Sea level rise on the order of 5 feet in 80 years is hardly going to make most countries uninhabitable. Over longer time scales will see much larger increases, but the yearly change is never projected to be that rapid. Water availability is a concern for farming and industry, but not really people. Desalination is cheap enough f…
As armchair academic I kind of understand you. People live in all sort of horrible conditions today - famine, malaria, diseases. As living person I ask myself what if my home was destroyed by flood? What if there is no water to grow food? What if person from the country which caused most of CO2 emissions [1] expects me to be contempt? Shouldn't I blow them up? Maybe all I need to commit is a good preacher.
Last mass migration caused by ISIS. COVID caused reduced oil consumption is enough to make a trouble for oil exporters. Global warming is worse - drought, flood, fires. World is extremely fragile, resources supplied from another part of the world, even today cobalt mining is horrible, what would be then? I've heard of another civilization and broken supply chains [2].
[1] https://ourworldindata.org/co2-emissions#cumulative-co2-emis...
[2] 1177 BC: The Year Civilization Collapsed (Eric Cline, PhD) https://www.youtube.com/watch?v=bRcu-ysocX4
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#469Earlier quoted context omitted.
Nuclear reactors run at cool temperatures compared to say gas turbines. And they are powerful. So the surface area for radiative cooling is proportional to the power divided by temperature to the fourth power. So the cooling would need to be very big.
Right, but there is no shortage of metals and ceramics that can maintain cohesion (and strength!) at high temperature -- I'm thinking about those videos the machinists post of tools slicing through metal at an obscene rate with incandescent tooling. You don't even need ceramics to do that, there are steel alloys that stay hard and strong enough to slice through (soft) steel while incandescent, although for wear optim…
My non-expert guess is that given the large amount of power you have in a small area in a nuclear reactor, it would be hard to reach equilibrium while keeping the fuel solid.
If the fuel is in a liquid state (as in a molten salt reactor), then you could more easily since you could have it pour into a wide container, increasing surface area. (Basically the freeze plug approach).
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#470Can someone refresh my memory? Is generating electricity directly from the products of fission proven [mathematically] to be less efficient than decay->steam->mechanical->electrical or is just that the applied science of steam power is so far ahead of everything else? My peace of mind would be much greater if the energy transfer went through solid state systems instead of a working fluid that is pretty good at carryi…
The problem is heat. fission produces a ton of it and it has to go somewhere. Yes, you can absorb radiation thrown off by fission, but you still have the problem that heat will melt everything. So you throw water (or salt) on the reactor, heat it up, and do work with the steam that is ultimately produced. It has less to do with steam being the ideal route and more to do the the practicality of dealing with heat. AFAI…
Most people are worried about the reactor transitioning to an open loop against the wishes of the maintainers.
But that’s good info, thanks. Molten salt still has to heat transfer to steam because we don’t have any thermovoltaics in the 50% efficient range.
I think I now understand that most of the heat comes from absorbing neutrons, which don’t like to generate electricity (vs betavoltaics and gammavoltaics). And any device inside the pressure vessel would be altered by those neutrons, need to be accounted for as another source of decaying particles, and need to be replaced.
And/Or, you’d want a completely different reaction and then need a neutron generator capable of running continuously.
That about right?