Nuclear Reactions at Chernobyl Are Spiking in an Inaccessible Chamber (newscientist.com) 119
Scientists monitoring the ruins of the Chernobyl nuclear power plant in Ukraine have seen a surge in fission reactions in an inaccessible chamber within the complex. They are now investigating whether the problem will stabilise or require a dangerous and difficult intervention to prevent a runaway nuclear reaction. From a report: The explosion at Chernobyl in 1986 brought down walls and sealed off many rooms and corridors. Tonnes of fissile material from the interior of a reactor were strewn throughout the facility and the heat it generated melted sand from the reactor walls with concrete and steel to form lava-like and intensely radioactive substances that oozed into lower floors. One chamber, known as subreactor room 305/2, is thought to contain large amounts of this material, but it is inaccessible and hasn't been seen by human or robotic eyes since the disaster.
Now, researchers have seen a spike in neutron emissions from the room, with levels increasing around 40 per cent since the start of 2016. This points to a growing nuclear fission reaction, so researchers are trying to determine if this surge will fizzle out, as previous spikes in other parts of the ruins have done, or whether they will need to find a way to access the room and intervene. Neil Hyatt at the University of Sheffield, UK, who studies nuclear waste disposal, likens the situation to "embers in a barbecue pit" and says "it's a reminder to us that it's not a problem solved, it's a problem stabilised."
One suggestion for why this is happening is that a new structure placed over the ruined reactor in 2016 is causing the plant to dry out. When uranium or plutonium fuel decay radioactively, they emit neutrons, which can promote a fission reaction if the neutrons are captured by another radioactive nuclei. However, large amounts of water slow these neutrons down, preventing them from being captured. The original shelter, which was hurriedly constructed over the reactor in the months following the accident, was riddled with holes that allowed rainwater and birds inside. If the rainwater was helping to suppress reactions in room 305/2, its absence due to the new structure could mean there is no longer enough water in the room to sufficiently slow neutrons down.
Now, researchers have seen a spike in neutron emissions from the room, with levels increasing around 40 per cent since the start of 2016. This points to a growing nuclear fission reaction, so researchers are trying to determine if this surge will fizzle out, as previous spikes in other parts of the ruins have done, or whether they will need to find a way to access the room and intervene. Neil Hyatt at the University of Sheffield, UK, who studies nuclear waste disposal, likens the situation to "embers in a barbecue pit" and says "it's a reminder to us that it's not a problem solved, it's a problem stabilised."
One suggestion for why this is happening is that a new structure placed over the ruined reactor in 2016 is causing the plant to dry out. When uranium or plutonium fuel decay radioactively, they emit neutrons, which can promote a fission reaction if the neutrons are captured by another radioactive nuclei. However, large amounts of water slow these neutrons down, preventing them from being captured. The original shelter, which was hurriedly constructed over the reactor in the months following the accident, was riddled with holes that allowed rainwater and birds inside. If the rainwater was helping to suppress reactions in room 305/2, its absence due to the new structure could mean there is no longer enough water in the room to sufficiently slow neutrons down.
10 Days Later (Score:5, Funny)
Well, at least the dupe [slashdot.org] isn't still on the main page...
Re:10 Days Later (Score:4, Funny)
So far it does not look like an runaway dupe chain redaction, but we should keep monitoring and get ready to send a team of editors down there if it becomes worse!
Okay, so start spraying water on the ground? (Score:3)
Obviously the exact cause and effect needs to be established, so that the situation can be controlled long term, but _right now_ you have:
* a quite concerning development.
* a reasonably simple explanation.
* a reasonable simple fix.
Unless someone can think of a reason why starting spraying water, to start soaking the soil, would be a stupidly dangerous thing to do, ....then maybe watering that ground. It's going to take days to reach down, so waiting until the situation gets much worse....sounds like a bad idea.
Re:Okay, so start spraying water on the ground? (Score:5, Interesting)
The hydrogen in H2O converts fast neutrons to slow "thermal" neutrons.
The problem is that thermal neutrons aren't necessarily less reactive, just differently reactive. For instance, fast neutrons will react with Li7, but thermal neutrons will react with Li6. Failure to understand that is why Castle Bravo had twice the pop that was expected.
So spraying water on the pile is likey a workable fix, but it is better to make sure we actually understand what is going on first.
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The hydrogen in H2O converts fast neutrons to slow "thermal" neutrons.
The problem is that thermal neutrons aren't necessarily less reactive, just differently reactive. For instance, fast neutrons will react with Li7, but thermal neutrons will react with Li6. Failure to understand that is why Castle Bravo had twice the pop that was expected.
So spraying water on the pile is likey a workable fix, but it is better to make sure we actually understand what is going on first.
IIRC, the RBMK is not a fast reactor, but uses graphite as the moderator and water for cooling. Finding out what is going on, as you point out, is critical to solving the problem or preventing one.
Re:Okay, so start spraying water on the ground? (Score:5, Insightful)
IIRC, the RBMK is not a fast reactor, but uses graphite as the moderator and water for cooling.
This is no longer an RBMK reactor.
It's now a RMRS (random mixture of radioactive slag) reactor.
Re:Okay, so start spraying water on the ground? (Score:5, Funny)
Where can one purchase these new-design RMRS reactors? I hear the maintenance costs are significantly lower than traditional designs
Nope. Not cheaper. (Score:2)
I hear the maintenance costs are significantly lower than traditional designs.
I know you're joking, but keep in mind: The NSC (New Safe Confinement) - that huge half-pipe thing that's.now covering the Chernobyl reactor and the old sarcophagus - is spec'd to last 100 years and cost(s/ed) north of 20 Billion Euros. That ain't cheap. Especially considering that we're going to need a few of those or some large-scale glass-enclosing + storage in bunker-concrete for radioactive waste that was cut into handy piece
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This is no longer an RBMK reactor.
It's now a RMRS (random mixture of radioactive slag) reactor.
that is Brilliant !!!
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Richard M. Richard Stallmann would like to object...
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He explained the effect of water. Not the effect of the original graphite.
Sprinkle water on it, and it might start moderating the fission neutrons. Simple.
Has nothing to d with the original design of the reactor, or how would a neutron know that it should not slow down when it bounces off from some water molecules?
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He explained the effect of water. Not the effect of the original graphite.
Correct. However, if the RBMK is a thermal reactor, which since it has a moderator I suspect it is, then what actually converted fast neutrons to thermal neutrons is irrelevant. In the RBMK's case, water was used to remove the heat created by fission and the steam produced to run turbines, not moderate as in light water designs.
Sprinkle water on it, and it might start moderating the fission neutrons. Simple.
Which the graphite does as well. Which is why it is important to understand what is happening within the slag.
Has nothing to d with the original design of the reactor, or how would a neutron know that it should not slow down when it bounces off from some water molecules?
It doesn't, whether it's water or graphite. The fuel doesn't care h
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Which the graphite does as well. Which is why it is important to understand what is happening within the slag.
The graphite burned away in the "explosion".
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Sprinkle water on it, and it might start moderating the fission neutrons. Simple.
Or, it might speed up the reaction, but slowing down the neutrons. The dual loop pressurized water reactor I worked on used water as a moderator to increase the number of reactions and hafnium rods to moderate the number of neutrons and control the reactor.
Other possible effects of adding water:
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Or, it might speed up the reaction, but slowing down the neutrons. ...
That is exactly what I wrote
So idea what you are ranting about.
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Sprinkle water on it, and it might start moderating the fission neutrons. Simple.
Or, it might speed up the reaction, but slowing down the neutrons. The dual loop pressurized water reactor I worked on used water as a moderator to increase the number of reactions and hafnium rods to moderate the number of neutrons and control the reactor.
Other possible effects of adding water:
Does it still sounds like a good idea?
Radioactive steam is not a thing.
You can have water contaminated with radioactive substances which is a concern of course.
Steam explosion requires confinement, unlikely to happen this way
Chemical reaction and/or destabilization could happen, but it would be similar to rain leaking in the last several decades.
The bigger concern is that reactivity has been increasing in general. That's unlikely to happen naturally during this time frame so an external factor (lack of water perhaps) is probably the cause.
It w
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Unless someone can think of a reason why starting spraying water, to start soaking the soil, would be a stupidly dangerous thing to do, ....then maybe watering that ground.
I think that part of the issue is that condensation inside NSC (New Safe Confinement) may compromise the structure over time from corrosion. The goal being to keep the structure going for as long as possible whilst they disassemble the reactor. There are things like cranes and gantries holding robotic jackhammers lowered from the ceiling for the planned disassembly of the building within NSC.
Now that we're seeing picture from within NSC it's much easier to imagine a day when the building is gone and th
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> I think that part of the issue is that condensation inside NSC (New Safe Confinement) may compromise the structure over time from corrosion.
Ugh. I wonder even how much info they have on "how to keep a structure standing for 5000 years, when it's not built in the shape of a pyramid.", let alone details about how corrosion affects buildings over that time frame.
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> I think that part of the issue is that condensation inside NSC (New Safe Confinement) may compromise the structure over time from corrosion.
Ugh. I wonder even how much info they have on "how to keep a structure standing for 5000 years, when it's not built in the shape of a pyramid.", let alone details about how corrosion affects buildings over that time frame.
IIRC they were aiming for 100 years, the rationale being much of the reactor is disassembled and 100 years worth of engineering effort to replace NSC with something else.
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NSC has air handling systems, so controlling humidity is somewhat trivial. Adding an insulation layer on the exterior might be a good idea, but it shouldn’t be necessary.
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NSC has air handling systems, so controlling humidity is somewhat trivial. Adding an insulation layer on the exterior might be a good idea, but it shouldn’t be necessary.
Ok. I was recalling what I read about the structure when it was being built saying that some areas of NSC were given special attention because they would become inaccessible once the structure was fully unfolded and put in place.
Air handling systems would make sense, I'm pointing out the effort they went to controlling humidity within NSC and a potential rationale for avoiding introducing lots of water *within* the structure. After all keeping the building in service for as long as possible means it will
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Again, no nuclear scientist but building a monolithic dome [slashdot.org] structure nearby (a few hundred meters from NSC) with say 70-80’ of clear height inside that can support a drilling rig would not seem like a huge ordeal— there are plenty of ways to deal with the foundation requirements and to avoid disruption of the soil, and constrution activity is all confined to the interior. When construction of the structure is done then you move to the remediation effort, and the dome can act like a confinement
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Also spraying in water means that now you have a load of contaminated water to deal with. If it pools it up can be quite heavy and cause stuff to collapse, and if it soaks things it can make them less structurally sound (like web paper). Just spraying water at the problem blindly is not a good idea even without the nuclear component of this accident.
Re:Okay, so start spraying water on the ground? (Score:4, Interesting)
I would guess that they don't want to do this because it would mean contaminating the ground water around the plant even more than it already has been contaminated. However, they probably would consider this if they felt it was needed and there wasn't any other good solution.
Easy test (Score:2)
If the idea is that lack of water is allowing fission to ramp up, then the easiest way to test this idea is to drill into this area and pump in a crap ton* of water.
If the fission dies down, congratulations. If not, you know at least one thing which won't work.
*A crap ton is significantly larger than a metric ton and thus suited for situations such as this.
Re:Easy test (Score:5, Funny)
*A crap ton is significantly larger than a metric ton and thus suited for situations such as this.
How does that relate to the metric shit ton?
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American here, how many football fields is that?
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4 chains and 2 rods.. about half the length of Times Square.
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Both the GP and the replier show that, even with all the dumb-ass trolls, /. still has hope.
And no one's even touched on metric furlongs or fortnights.
Re:Easy test (Score:5, Funny)
How does that relate to the metric shit ton?
It's the closer metric unit to the long imperial assload as opposed to the short imperial assload.
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If the fission dies down, congratulations. If not, you know at least one thing which won't work.
... and if you're lucky, you didn't just make things worse!
"Fuck around and find out" certainly has its place, but ... I'm not sure this is the place for it unless we've done the possible testing and can be reasonably sure that this is a risk worth taking.
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The units stuff is very funny.
But wont pumping water in make the water very contaminated?
And where will the water go after that?
Utterly moronic question warning: (Score:3)
Ok, I know I am no nuclear scientist or anything, but at this point I would assume they have a level of 3D mapping of the ruins, and could use directional drilling technology to access anything they needed to. I get that once you hit a certain point the radiation will cause problems, and a similar issue for heat but is it so bad that you cannot get within 1-2m of a point of interest?
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Why would you want to make a hole between the nuclear mess and the outside world? That's the very thing they've been trying to avoid up till now.
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A bendy, small-diameter hole specifically. Either from within the “new safe” containment building, or from a separate structure to perform a similar function of containment. Shielding it should be fairly trivial, although you might want to do something to pressurize it to prevent water ingress, but I honestly don’t know.
I can imagine the biggest issue is boring a hole with continuous casing, as I am not sure how they would be cast when you go horizontal.
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Further edit— I don’t imagine they could possibly drill through the reactor containment vessle, at least not safely, but going through (heavily reinforced) concrete should not be a huge problem technically.
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>> I don’t imagine they could possibly drill through the reactor containment vessle
There is no containment, and no vessel there any more.
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Because exposing whatever is causing this might not be a good idea. Need to figure out what it is and what to do about it first.
Also the chances of hitting the right spot first time are limited, and drilling will release a lot of radioactive dust and the containment isn't airtight. Plus the release of dust makes all the other work much harder.
Oh, and you have to get this drilling equipment in there somehow and have it operated remotely. By itself no easy task.
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Ok, I know I am no nuclear scientist or anything, but at this point I would assume they have a level of 3D mapping of the ruins, and could use directional drilling technology to access anything they needed to. I get that once you hit a certain point the radiation will cause problems, and a similar issue for heat but is it so bad that you cannot get within 1-2m of a point of interest?
I'm not a nuclear scientist either, but I did take some manufacturing classes and am familiar with drilling processes. The problem with drilling a hole is what to do with the chips? Chips are the material removed when drilling or cutting. As you get closer to the remains of the reactor, the chips brought to the surface will likely contain greater and greater amounts of contaminated material. Some of that material will be very fine, and could easily become airborne. Using a cutting fluid [wikipedia.org] will help immen
Rebranding for the Nuclear Industry (Score:1, Insightful)
Nuclear Energy: the gift that keeps on giving.
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Industry? Commies made a reactor without containment.
Re:Rebranding for the Nuclear Industry (Score:5, Informative)
Ever hear of Three Mile Island? Fukushima Dai-Ichi?
So there have been basically two major nuclear powerplant accidents outside of the USSR, one of which, TMI, released almost nothing into the environment.
So of all the nuclear power generated outside the USSR, you could name two power plant accidents. This is why the deaths per TWh are lower for nuclear than any other method of power generation.
Kyshtym?
Lumping in Soviet era nuclear weapons plants under civilian nuclear power is somewhat disingenuous don't you think?
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Deaths is a very specific metric. For anyone considering investing in nuclear power, cost is an important factor. There have been many expensive accidents, not to mention the cost of preventing them happening in the first place.
There's also the potential risk. So far a certain amount of luck has prevented these accidents from becoming even more expensive. Fukushima is looking like half a trillion Euros, but could easily have been much worse.
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Why don't you ask the insurance industry why, TO THIS DAY, they flat-out refuse to ensure nuclear generating facilities unless governments agree in advance to cover 90% of the damages if anything goes wrong. Maybe that will give you a clue.
As for "disingenuous"...you think a problem will go away overnight? LOL. Dumbass.
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As for "disingenuous"...you think a problem will go away overnight? LOL. Dumbass.
Tell me what nuclear Soviet weapons have to do with western civillian power lol dumbass?
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Plutonium from civilian reactors in the USA aren't and weren't used for that. The US government had its own reactors to make that stuff and stopped in 1987. They have 80 tons of the stuff in inventory, consider a weapon with their reflectors and initiator needs much less than the spherical critical configuration of 11kg, crude estimate would be enough for over 20 million bombs.
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Ever bothered to research Three Mile Island? The accident was caused by human error, the fail safe systems worked exactly as designed. No significant radioactivity was released into the environment. That is what happens when you have a issue with modern nuclear reactor.
Fukushima was also caused by human error. The reactors shouldn't have been placed where they where and corners where cut on the safety systems.
Soviet nuclear reactors are garbage, poorly designed, and are accidents waiting to happen
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Yes.
Three Mile Island has containment, and so the public was not exposed to any radiation above background levels.
Fukushima was mostly a spent fuel pool disaster, guess putting backup generators below sea level next to sea is stupid. Yes, as far as reactor and silly containment ring engineer at GE screamed bloody murder about that thing, he was right.
Kyshtym, another commie system.
Re:Rebranding for the Nuclear Industry (Score:5, Insightful)
It does. It is the most efficient energy system out there. Without nuclear energy there would be nothing. No matter, no life, nothing.
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It's great when it's 93 million miles away...and nothing major goes wrong with it. I wonder what another Carrington Event would do to us today.
No fact checking jouranlists again. (Score:4, Interesting)
However, large amounts of water slow these neutrons down, preventing them from being captured. The original shelter, which was hurriedly constructed over the reactor in the months following the accident, was riddled with holes that allowed rainwater and birds inside. If the rainwater was helping to suppress reactions in room 305/2, its absence due to the new structure could mean there is no longer enough water in the room to sufficiently slow neutrons down.
This is the opposite of true. Water is a moderator which makes the neutrons more likely to cause fission, not less. Rainwater was accelerating the reaction if anything. There are really two possibilities: either 1) more weight has shifted onto a fuel rod compressing it or 2) a fuel rod has fallen into some water. Drying out the chamber should fix issues like then, not cause them.
Re:No fact checking jouranlists again. (Score:5, Interesting)
This is true only for *some* reactors - RBMK reactors had a high positive void coefficient, which meant that the reaction increased as coolant boiled off....
That said, who knows what composition makes up the sludge down there - I doubt there are many pristine or even recognisable fuel rods underneath the reactor, its all going to be "corium", ie melted fuel mixed with pretty much anything else it could melt.
It could be as simple as degradation in materials bringing two corium masses together after all these years.
Re:No fact checking jouranlists again. (Score:4, Interesting)
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RBMK is a great example of how commercial factors compromise nuclear safety.
RBMK was designed to provide very high power output (1.5GW) but also be cheap to manufacture and operable by local, low skill workers. Every decision that compromised its safety and lead to the accident at Chernobyl being possible was driven by the desire to make a low cost, mass produced reactor that didn't need expensive or complex parts like a massive pressure vessel.
In many ways it was a lot like modern proposals of modular reac
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RBMK is a great example of how commercial factors compromise nuclear safety.
RBMK was designed to provide very high power output (1.5GW) but also be cheap to manufacture and operable by local, low skill workers.
This is I think a slightly odd reading of it. Part of the reason it was so wildly unsafe is it was designed as a dual use machine, to be able to cook plutonium for nuclear weapons while making power all from unrefined natural uranium. And of course cheap, but it's a stretch to call that a commercial c
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It wasn't designed for dual use, it was designed along the lines of a military reactor because military reactors are what its main designers knew best. RBMK is simply a scaled up Obninsk reactor. [wikipedia.org]
Even a command economy has budgetary constraints especially in the case of the Chernobyl power plant that was manufactured not by the usual department of medium
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It wasn't designed for dual use,
It was designed for both power and plutonium production. It produced 1000MWe, so its power output wasn't by any means trivial. RBMKs are still putting about 8GW into the Russian grid and no longer used for plutonium production.
Even a command economy has budgetary constraints
You know it would be nice if you actually read what I wrote rather than stopping a few words in and repeating what I wrote back to me.
Moreover they simply didn't have the required industrial capacity to m
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You are the one who is failing to understand what you have read. RBMK is not designed for dual use. It was thought, many decades ago, that it was, but nowadays the information about it is readily available.
And I read what you have written. This
really shows you have no idea how stuff worked there.
Yes, because the Canad
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You are the one who is failing to understand what you have read. RBMK is not designed for dual use. It was thought, many decades ago, that it was, but nowadays the information about it is readily available.
You are completely mistaken. It was designed for dual use. It was a bad design as it turns out but it was still designed that way.
Can you see the pattern now or is it still eluding you?
You flinging random facts at the page isn't a pattern. Try assembling them into an argument and we can talk.
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The plutonium production wasn't the main reason it was unsafe, it was the cost factor. At the time the only other design available was the VVER, which requires an expensive pressure vessel. The RBMK was also very large and powerful by comparison, and developed quickly - there were no prototypes, it went directly into mass production. The large size meant that building a containment building would have been extremely expensive, so they didn't.
In fact around 1967 major changes were made to the design which ma
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Re:No fact checking jouranlists again. (Score:4, Interesting)
Yes, I wish I had mod points.
One of the reasons water-cooled reactors stabilize themselves is that if boiling starts, the steam bubbles have less water than the condensed liquid, the amount of moderation goes down, and the reaction goes back down.
Adding water can cause a "criticality accident", in fact.
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One of the reasons water-cooled reactors stabilize themselves
That's true of some reactor designs. Chernobyl is not one of those designs. Instead, the reaction inside increases as the coolant boils off.
Re:No fact checking jouranlists again. (Score:5, Interesting)
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Which means you can't say one way or another whether water is acting as the moderator.
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On a recent documentary about Chernobyl, one of the survivors of the cleanup said that flooding the radioactive remains with water could have caused another hydrogen explosion. If the graphite in the remains of the reactor is hot enough, it will react with water to produce hydrogen. If there is air in the containment volume, the hydrogen will detonate, and blow it all up again. As far as I know, many metals will also produce hydrogen when they react with water at sufficienly high temperature. A major danger
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There is another possibility that you have missed. It's called a decay chain. That is in the complex soup that is the fuel-containing material/corium some will have decayed to other isotopes, and they could now have reached a sufficient concentration that their decay is now having an impact on what is going on.
Further the corium is undergoing physical degradation
Basically nobody really knows what is going on in the corium and predicting what will happen in the future is mostly a guessing game. 20 years ago
And.. ? (Score:3)
And what happens if there is a "runaway" reaction? It can't destroy the containment, because we did that already 25 years ago. I can't see it accumulating hydrogen, because nothing is that well sealed anymore. So what are they worried about happening this time?
Re:And.. ? (Score:5, Interesting)
The worst case scenario is similar to what they were worried about back then - either the reactor catches light again, and releases significant radiation bearing pollution into the atmosphere (which the current containment vessel is not designed to prevent - its not air tight), or it gets hot enough to melt through the lower bounds of the reactor building, through the lowest concrete barrier, into natural soil and down to the water table, where it could cause a huge steam explosion which eclipses the original disaster... Or both of these.
Re:And.. ? (Score:5, Interesting)
I covered this topic for Hackaday a few days ago: https://hackaday.com/2021/05/14/increased-neutron-levels-at-chernobyl-4-how-dangerous-is-corium/ [hackaday.com]
This is a situation that has been (slowly!) developing over the past four years, ever since the NSC was put in place and was not unexpected. At this point the neutron flux density is still far below levels where one would raise alarm.
add water (Score:4, Interesting)
If the rainwater was helping to suppress reactions in room 305/2, its absence due to the new structure could mean there is no longer enough water in the room to sufficiently slow neutrons down.
I am not an expert, so there is nothing to prevent me from asking the obvious naive question: Why not pump in some water with a good neutron absorber in suspension or solution, such as boron or a boron compound? Maybe they do not want to pump in so much that it floods into local aquifers, if the local groundwater is not already. a lost cause, but seems like they could replace the amount which has dried away without substantially spreading radioactive contamination.
Re: add water (Score:4, Interesting)
Because drying out is a theory. What if it's wrong and the water you pump in there turns to radioactive steam that gets into the atmosphere? The protection shell is not airtight nor can it protect against future explosions.
Also, it's inaccessible, so no way to pump water to it without drilling in from elsewhere, and if you do that, you've now made a way for whatever is currently somewhat contained to be more exposed.
Watch for radioactive spiders/villains/superheros (Score:2)
I've seen a lot of movies that start that way :p
Q: What has wings and glows? (Score:2)
A: Chicken Kiev.
I'll show myself out now.
Not great. Not terrible. (Score:2)
Yet.
'nuff said
Wow! Chernobyl Season 5!! (Score:2)
Re:Wow, global warming really is an issue (Score:4, Informative)
No, there isn't any chance of that. For several reasons, not least being that nuclear power plants REQUIRE water to do the whole fission thing. You get fission in one of them by adding water to moderate the neutrons. Lack of water turns off the fission process....
Now, if a reactor is actually doing the whole fission thing (you know, is producing power), then draining the water will get it REALLY hot. Hence the whole "meltdown" thing. But the fission reactions will stop pretty much as soon as the last of the water is gone.
Caveat: the kind of reactor that is designed to produce fissionables (which means a weapon manufacturing reactor) won't necessarily work that way (there are several ways to design a reactor to produce fissionables, and not all of them require water, though most do), but that's not something to worry about outside a nuclear weapon production plant, which Chernobyl wasn't....
Re:Wow, global warming really is an issue (Score:5, Informative)
*Some* nuclear reactor designs require water as a moderator, neutron absorber and as a coolant, meaning they have a reasonable negative void coefficient - which in turn means the reaction slows down when the moderator or coolant is removed.
However, RBMK reactors at the time of the Chernobyl accident had a high *positive* void coefficient - the reaction speeds up as more voids appear in the moderator or coolant, ie steam or low coolant levels (or no coolant at all). Which means the bang can happen.
RBMK reactors were also weapons grade plutonium producers by design - but there isn't anything immediately available on whether Chernobyl was in fact producing at the time.
Re: Wow, global warming really is an issue (Score:5, Informative)
Of course Chernobyl was producing plutonium! Thatâ(TM)s a bit like asking if an aquarium is wet.
Every uranium reactor produces plutonium. The particle flux transmutes some of the non-fissile uranium isotope into plutonium.
The process of reprocessing nuclear waste is at least in part removing the plutonium â" too much plutonium in the fuel is dangerous.
This is why we have the nuclear non-proliferation treaty - to give nations nuclear electricity, but supposedly ensure the plutonium waste is correctly disposed of. Violating that treaty (keeping the plutonium) is how North Korea gets plutonium for their nukes.
Chernobyl was designed so plutonium was removable (Score:2)
Of course Chernobyl was producing plutonium! That (is) a bit like asking if an aquarium is wet.
Every uranium reactor produces plutonium
The Chernobyl RBMK reactors were Graphite moderated instead of Water moderated
this meant that the fuel rods could be removed while it was still operating which makes the high grade plutonium produced
much easier to remove and is similar in design to the reactors used to make Nuclear weapons.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Re: (Score:3)
I really don’t see the relevance of how the reactor is moderated to whether it produces plutonium. Uranium reactors produce plutonium as a byproduct. The amount & “quality” isn’t terribly relevant, as tons of plutonium can be produced. The ~1% plutonium content in “spent” fuel from a water-moderated reactor is quite a bit when you deal with with the amount of fuel in a 1000 MW reactor.
The big “feature” of the RBMK was it used natural, unenriched uranium fo
Re: (Score:2)
I really don’t see the relevance of how the reactor is moderated to whether it produces plutonium
It will produce *some* plutonium mix in any case, but weapons-grade plutonium output requires a short fuel cycle which RBMK was designed to facilitate. So to you the quality of the plutonium may not seem relevant but to USSR it definitely was relevant. No amount in tonnes would fix the Pu240 contamination they wanted to avoid.
The big “feature” of the RBMK was it used natural, unenriched uranium for fuel
Only initially. They had to use enriched fuel for stability. At Cherobyl's explosion's time they were using fuel enriched to around 2%.
Re: Wow, global warming really is an issue (Score:3)
Chernobyl is a graphite reactor. They used graphite to moderate the reactions. Just before the meltdown they were experimenting with one of reactors testing various ideas. When it started going to fast. Thus the melt down.
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Chernobyl is a graphite reactor. They used graphite to moderate the reactions. Just before the meltdown they were experimenting with one of reactors testing various ideas. When it started going to fast. Thus the melt down.
You aren't wrong, but you're missing a major step. The reactor didn't 'melt down' directly from the tests, it went prompt-(super)critical and the resulting extreme heat flash-boiled the cooling water resulting in a a steam explosion. That steam explosion disassembled much of the core and halted the prompt-critical reaction. The remaining nuclear fuel in the destroyed core continued it's (no longer critical) fusion reaction, with no functional cooling, overheated and melted down.
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The "meltdown thing" is not caused by the fission process. As you stated: that is already over.
But by the decay energy of the fission products.
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The "meltdown thing" is not caused by the fission process. As you stated: that is already over.
But by the decay energy of the fission products.
No. A steam explosion was caused by the prompt-critical/super-critical reaction.
Decay energy = fission = what melted the remainder of the core
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No. A steam explosion was caused by the prompt-critical/super-critical reaction.
Actually no.
The explosion was caused by burning graphite. If there was a "mini steam explosion", it only can have killed the heat conduction pipes from the core to the turbine. Which has nothing to do with the explosion of the reactor itself.
Re: (Score:2)
If the climate is hot enough for the water to eventually evaporate out
If the water isn't being replenished by rain from above, it will naturally seek to fall down (through whatever porous substances it's in) to the level of the water table. And the nuclear reactions are supplying constant - and possibly rising - heat to help boil it away.
On which planet are you talking about? (Score:2)
That's why Sahara is moving up and the net territory of Sahara is decreasing
https://www.sciencedaily.com/r... [sciencedaily.com]
https://www.nature.com/article... [nature.com]
before, during or after its current expansion?
Re: (Score:2, Informative)
The Sahara is doing whatever [newscientist.com] it has to in order to support today's narrative.
Re: On which planet are you talking about? (Score:2)
Re: (Score:3, Insightful)
That's why Sahara is moving up and the net territory of Sahara is decreasing
https://www.sciencedaily.com/r [sciencedaily.com]...
https://www.nature.com/article [nature.com]...
before, during or after its current expansion?
Another victim of that conservative *climate change is actually a good thing* propaganda wheel.
First they tried to outright deny it. As the scientific and global concensus became overwhelming, they have shifted the narrative to how we can continue to burn oil because of how awesome global warming will be.
Re: On which planet are you talking about? (Score:5, Informative)
Woah, that escalated quickly.
Maybe we're both right and wrong. Here's a good answer from a scientific redditor:
Is the Sahara desert shrinking or expanding?
Good question. It is almost pointless to try and find out whether the Sahara is growing or shrinking, because of the sheer size of the desert (as well as demarcating what exactly constitutes 'desert'). In the late 90s to mid 2000s, the thought was that the Sahara desert was expanding southwards by a certain extent each year. This was of course somewhat exaggerated. On the other hand, so is the perception that the deserts are 'in retreat' as these articles seem to imply.
The thing is, between the late 70s to late 80s, there was a significantly dry period in the Sahel region (the transition zone between the Sahara and the savanna) which exacerbated the effects of desertification, leading to the perception in the 1990s-2000s that the desert was indeed expanding. However, over the last 15-20 years in terms of precipitation, the region has been in a comparatively very wet period. Relative to the significant drought the area previously experienced, it may seem that the deserts are in 'retreat' but arguably that is essentially what is expected in terms of how vegetation has responded (it gets a bit more complicated because some of the previous mesic vegetation has been replaced by xeric vegetation in certain areas so while it is greener, it is not quite the same)
I hope this help. I could go into more detail but this should give you an idea of how complicated it is to understand.
Source - My dissertation research has broadly to do with understanding how vegetation responds to moisture events
As for this here:
Now do us a favor take your partisan attitude, shove it so deep into your arsehole so it protrudes from your mouth and get bent, asswipe
I do have a partisan attitude, because over the years I've just witnessed how conservatives have completely distanced themselves from reason, and instead chosen to embrace conspiracy theories and science-denial, whilst spreading lies and FUD like there's no tomorrow -especially the word-twisting and cherry picking Fox & Friends people. And all of this resulted into the climax that is Trumpism and people that are increasingly out of their minds, like QAnon.
I just can't take all of that bullshit anymore.
But I would never insult someone in such a vile and vulgar manner as you decided to insult me. Not even over the Internet. So instead of judging on my partisan attitude, perhaps you should reflect upon what is wrong with your character.
Re: (Score:2)
Re: (Score:2)
Reactor is located in Ukraine, near the border with Belarus. It's about 100km away from nearest Russian border, and something like 400-500km away from a nearest large Russian city of Kursk (yes, of the WW2 battle fame).
Re:Just send in all the Slashdot nuclear advocates (Score:4, Informative)
..they have all the answers
We do, but the answer is don't build a reactor like the RBMK which is fucking insane. Fortunately Western Bloc nations knew this and didn't.
Thing is the anti-nuclear lobby expect the pro nuclear people to somehow have control over a closed regime with a record of not giving a crap about human lives thousands of miles away operating before they were born. That's pretty dumb.