Comment on rollin' coal
captain_aggravated@sh.itjust.works 6 months agoIt is my understanding that the Three Mile Island incident was a meltdown, that the fuel rods got hot enough to melt themselves and pool in the bottom of the reactor vessel but did not escape containment, unlike Chernobyl whose reactor core is currently a big lump in a sub-basement.
Chernobyl is a big lump in a sub basement, but that was still the result of a chemical explosion, not a meltdown. My point was that the only meltdown incidents have been caused by the US.
TMI is a bit of a sticky wicket, because as you say the roda did melt, but we got it back under control before abything more than some steam escaped containment.
so technically, it wasn’t a chemical explosion at chernobyl, it was a steam explosion, followed by a possible hydrogen explosion, though that would have been due to chemical reactions ultimately iirc.
Also technically, chernobyl is a meltdown incident, meltdown is described as “severe core damage” And considering that core no 4 no longer fucking exists, i think it’s fair to call it a meltdown incident.
You can have severe core damage without any nuclear reactions. A meltdown is severe core damage caused by a nuclear reaction that got out of control.
There aren’t “steam explosions” in physics. There are chemical reactions that cause an explosion, pressure buildups that cause an explosion, and nuclear explosions.
The steam was a pressure buildup that caused the incident resulting in an initial pressure explosion. The thing that “melted” the core of Chernobyl was the hydrogen exploding, hence a chemical explosion. Had it been a nuclear event that melted that core, neither Kiev nor Moscow would be inhabitable. The capital of Russia would be St. Petersburg, and Ukraine wouldn’t exist, as well as several other Soviet Oblasts in the area.
You can have severe core damage without any nuclear reactions.
uh actually, i disagree, because in order for the event of a meltdown to establish any amount of core damage, or damage at all, you need to inflict fission. Otherwise literally nothing will happen, because thats how they generate heat, but i’m no nuclear physicist.
There aren’t “steam explosions” in physics.
yes? there are? Have you ever looked into 19th century steam technology? Do you understand how combustion explosions work? Yes technically it results from a chemical reaction of smokeless powder decaying, but unless you confine that reaction into a space, it just goes woosh. Once you confine it, and allow it to compress itself it can explode. You are literally just pedantically claiming that steam explosions aren’t a specific subset of pressure explosions, the only reason that they are is because steam explosions are so easy to create, and so incredibly dangerous, that them existing in their own field is actually useful to current safety practices.
This is why properly regulated steam boilers can be used to provide steam to a steam engine to pull freight. But the second you get a low water level slosh event, and it sloshes back, the entire thing flashes immediately, blowing up the boiler, and if not immediately killing the crew, scalding them so badly they die shortly after because their lungs no longer function. I suppose you could argue that the burning of wood or coal is a chemical reaction here, but at the end of the day, it’s the heat that turns water into steam, and steam that makes the power.
The steam was a pressure buildup that caused the incident resulting in an initial pressure explosion. The thing that “melted” the core of Chernobyl was the hydrogen exploding, hence a chemical explosion.
or maybe it was just the heat from the fuel and resulting runaway fission chain that caused everything to melt into a pile of nothingness? Nuclear fuel just sitting idly by, allowed to exist as is unmoderated (in significant enough capacity) will literally eat through concrete. That’s why it’s called corium.
Had it been a nuclear event that melted that core
it wouldn’t have been, because that’s not possible, and i never said that was the likely event. I just said that it was a steam explosion, which it was, and a potential hydrogen or secondary steam explosion, of which we aren’t really sure on the source of.
Fucking with the literal power of atoms, in a mostly controlled environment, is the closest we’ve ever come to the Icarus myth.
idk man, maybe fucking castle bravo at bikini atoll? The one time we weren’t sure whether or not a sustained nuclear fission event would ever stop because theoretically it could process the nitrogen in the air into more fuel, causing the entire earth to turn into a nuclear wasteland (it didn’t btw) Nuclear fission as used to generate power is literally the safest possible use case of it. Modern reactor designs are literally incapable of having runaway thermal events. Research reactors use a specific blend of fuel TRISO to be specific, that has a specific formulation, that makes it physically incapable of having a thermal runaway.
I’m fairly certain that fusion power, should it ever come out of the theoretical stage, won’t be nearly as dangerous as fucking around with fission the way that we currently do.
i mean, fusion is likely to be less dangerous, i’ll give you that. But not even that significantly, the main benefit to fusion is that it’s the even more spicy nuclear bomb technology, and therefore, easier to exploit.
What do you think a “meltdown” is?
When the melted bit, caused by an uncontrolled nuclear reaction, escapes containment.
KillingTimeItself@lemmy.dbzer0.com 6 months ago
Ok so TMI, is actually a cumulation of three primary factors, none of which should’ve happened.
The first was that they had bad/broken gauges and equipment that was hard to read, meaning they didn’t know the state of the reactor exactly like they should have been able to.
Second, they had the auxiliary cooling pumps shutdown for maintenance. Now normally this wouldn’t be a huge problem if you’re following procedure, as procedure dictates (this was also the law btw) that when your reactor core is running, the auxiliary cooling lines need to be active.
And third, the reactor core was operated under only the primary water feed lines. I.E. power generating feed water. Which as i said is not allowed.
Once they had a crew change, the new crew immediately realized everything had melted down, and called for shutdown. Only took like 8 hours or something.
Chernobyl was a little more complicated, because chernobyl wasn’t designed with a PCV (primary containment vessel), technically it had a secondary containment, which would be the building around it, but obviously that didn’t help. It was theorized and believed by the engineers (and the operators, ignoring a certain condition where this wouldn’t be true, which nobody knew about) that it was impossible for the plant to have a meltdown, primarily due to the fact that it was such a spread out core, making it react slower to immediate changes in the power production.
However, during the day when this happened, (i wont go into all the detail because i will be here for hours otherwise.) the plant was in a xenon well, meaning that it was able to produce virtually zero fission (xenon absorbs neutrons) and the operators didn’t realize it, so they pulled out nearly all of the control rods trying to bring it back up (for a loss of power test) only to then have all the xenon start decaying at about that period of time, which meant the power level started to aggressively increase, and since there were no control rods, it sort of hit a runaway condition. Leading to the entire plant fucking exploding, due to a steam explosion specifically. This one was a lot more like a steam boiler explosion in a locomotive than a nuclear explosion or even hydrogen explosion (though that could’ve been the second explosion that happened)