How Hot is Ukraine Gonna Get?

[_Morpheus_]

4 minutes ago, Joe982 said:

Ukraine cut the water supply to Crimea way back in 2014, so water to Crimea is not the issue.

Blowing the dam benefits Ukraine more than the Russians as a number of Russian defensive positions will be flooded.

If the Ukrainians advanced and then, sometime later, the Russians blew the dam it could cause unknown problems for the Ukrainian forces. Therefore I think the Ukrainians blew the dam to eliminate the unknown.

 

 

Amazing analytical skillset..... i could bet you have the same opinion related to the Holodomor.
What happen this is disaster for the Ukraine, Ukrainian people, Ukrainian nature!
Only russians don't give a ..... about anything as they proof it already many times.

[Ultradave]

5 minutes ago, _Morpheus_ said:

Amazing analytical skillset..... i could bet you have the same opinion related to the Holodomor.
What happen this is disaster for the Ukraine, Ukrainian people, Ukrainian nature!
Only russians don't give a ..... about anything as they proof it already many times.

Russia also seems to be determined to test the robustness of the nuclear power plant, in several different ways. Odd, since any release would head toward them. But then, it's the Russians. Those on the ground there either don't think that deeply about consequences or don't care.

Do not recommend. 

Dave

[Fenris]

15 minutes ago, Joe982 said:

Ukraine cut the water supply to Crimea way back in 2014, so water to Crimea is not the issue.

Blowing the dam benefits Ukraine more than the Russians as a number of Russian defensive positions will be flooded.

If the Ukrainians advanced and then, sometime later, the Russians blew the dam it could cause unknown problems for the Ukrainian forces. Therefore I think the Ukrainians blew the dam to eliminate the unknown.

 

 

Some of what you say may well be true, but how exactly would UKR have managed to blow up a structure of that size and strength in one go whilst it is well within the russian area of control?

[Kraft]

21 minutes ago, Joe982 said:

Ukraine cut the water supply to Crimea way back in 2014, so water to Crimea is not the issue.

Blowing the dam benefits Ukraine more than the Russians as a number of Russian defensive positions will be flooded.

If the Ukrainians advanced and then, sometime later, the Russians blew the dam it could cause unknown problems for the Ukrainian forces. Therefore I think the Ukrainians blew the dam to eliminate the unknown.

 

 

Except those "defensive positions" were manned so thinly a group of guys on rubber boats could cross and blow up a command post with the only casulties coming from sea mines.

Its a paper thin line, that now cannot be properly crossed, sparing Russia from committing troops and heavy equipment there to counter Leopards etc.

 

Edited June 6, 2023 by Kraft

[Bulletpoint]

27 minutes ago, Ultradave said:

It's nothing to do with steam by the way. (probably the translation or lack of accurate knowledge by the original writer). It's water. Steam is transparent to neutrons so really has no effect on reaction rate

Isn't the problem that when steam bubbles form in the water between the fuel rods, those bubbles form voids where there is no water to block free neutrons, meaning those neutrons continue to reach more fuel, causing more fission, releasing more neutrons, etc?

[Butschi]

12 minutes ago, Ultradave said:

Sure I remember. That was the RBMK reactors like at Chernobyl. They had a "positive temperature coefficient"  or  "positive reactivity coefficient" (those mean the same thing) meaning that as temperatures in the coolant increase, the nuclear reaction rate increases, which increases temperature, which increases nuclear reaction rate.....  you can see where that leads. HOWEVER, this is not the design of these reactors. These are more "typical" reactors that have a "negative temperature coefficient".  Reaction rate decreases as water temperature increases. Should be obvious that that is beneficial and is how most reactors are designed. I believe RBMK reactors were the way they were for weapons materials production, for one thing. They also had no containment, which the Russians justified by their strict operating procedures preventing accidents. Ironically, Chernobyl's root cause was a) the violation of multiple operating procedures and parameters, b) running an unapproved test procedure, c) lack of understanding by the operators of the physics of the plant and the indications they were receiving (those are related). 

It's nothing to do with steam by the way. (probably the translation or lack of accurate knowledge by the original writer). It's water. Steam is transparent to neutrons so really has no effect on reaction rate, other than if you've got steam in the core you've got NO cooling, which is of course, very bad. Steam flow is an incredibly poor heat transfer mechanism. Steam is the RESULT of efficient heat transfer.

In my qualification training (18 months) to be licensed for start up testing of US Navy reactor plants one things was drilled into us (well, many things, but) That was "Believe your indications and act on them".  If you have an indication of something going wrong and you take all the steps to shutdown and "put the plant is a safe condition" (that's the key words), you can't go wrong. You may waste time if it turns out to be faulty indicators, but you won't break the plant or kill someone. Our motto in the shipyard nuclear test organization - "When in doubt, shut it down"   An operating sub doesn't necessarily have that option, but many times they do, and that's the reason why we build and test them so well, so that it doesn't come up.

Dave

 

Thanks, cool to have a real expert on the topic. As a physicist I had reactor design as a small part of a university lecture, so orders of magnitude less expertise.

I does have to do with steam, though, as far as I remember. As you say, steam is transparent to neutrons. So when you use water as moderator, you get (steam) bubbles as the temperature increases, which are no longer moderating the neutrons. Unmoderated neutrons can't cause a chain reaction, so the reaction rate decreases. That's why you get that negative coefficient. RBMK reactors use graphite as moderator, right? Obviously there's no steam, and so the word steam bubble coefficient would be misleading here, I guess.

[poesel]

14 hours ago, Huba said:

If you think about it, it's way easier to find spare aircraft than spare tanks here in the West. There were some news today that even Germany is reconsidering participation in the aircraft coalition.

Yes, but only by supplying missiles and support. No planes, we don't have any that are currently in discussion.

[Butschi]

5 minutes ago, Bulletpoint said:

Isn't the problem that when steam bubbles form in the water between the fuel rods, those bubbles form voids where there is no water to block free neutrons, meaning those neutrons continue to reach more fuel, causing more fission, releasing more neutrons, etc?

The other way round, actually. A neutron from nuclear fission has too high energy to be absorbed and cause more nuclear fission. The moderator reduces the energy of the neutrons and thus increases the reaction rate.

[_Morpheus_]

33 minutes ago, Ultradave said:

Russia also seems to be determined to test the robustness of the nuclear power plant, in several different ways. Odd, since any release would head toward them. But then, it's the Russians. Those on the ground there either don't think that deeply about consequences or don't care.

Do not recommend. 

Dave

Ok, but I don't see the truck with TNT on the dam. What I'm clearly see that it was blowed up from the inside, so actually somebody should unload this truck with TNT in the dam and push the button, correct ?
 

 

Edited June 6, 2023 by _Morpheus_

[Ultradave]

I think you quoted the wrong person 

[_Morpheus_]

Just now, Ultradave said:

I think you quoted the wrong person 

Just want to add additional comment to the discussion 

[DesertFox]

Something is in the air at Topmak

 

 

[panzermartin]

17 minutes ago, _Morpheus_ said:

Ok, but I don't see the truck with TNT on the dam. What I'm clearly see that it was blowed up from the inside, so actually somebody should unload this truck with TNT in the dam and push the button, correct ?
 

 

There is a note below this video: "The video provided is outdated" Its actually from 2022 it says.

[Eddy]

Seeing as though it's such a quiet news day I'll just drop this here.

UA getting even more help from the Czechs:

 

 

[Ultradave]

20 minutes ago, Butschi said:

Thanks, cool to have a real expert on the topic. As a physicist I had reactor design as a small part of a university lecture, so orders of magnitude less expertise.

I does have to do with steam, though, as far as I remember. As you say, steam is transparent to neutrons. So when you use water as moderator, you get (steam) bubbles as the temperature increases, which are no longer moderating the neutrons. Unmoderated neutrons can't cause a chain reaction, so the reaction rate decreases. That's why you get that negative coefficient. RBMK reactors use graphite as moderator, right? Obviously there's no steam, and so the word steam bubble coefficient would be misleading here, I guess.

This is kind of going down the rabbit hole, but for best heat transfer you DO want tiny steam bubbles (nucleate boiling). They form on the surface of the fuel, detach, and collapse in the bulk water coolant - VERY efficient heat transfer as the tiny bubbles give up their latent heat of vaporization. But there is a term called DNB (departure from nucleate boiling). This is where large steam voids form on the fuel because it is too hot, and they essentially blanket the fuel surface with steam. Less heat transfer, fuel overheats. 

Yes, RBMK (were, I believe none are operating anymore?) are graphite moderated, water cooled. A PWR or BWR is water moderated, water cooled.  So steam or no, the graphite moderator is there, creating plenty of thermal neutrons for continued fission. If you get a core full of steam in a PWR, you lose the moderating effect. Also, even just hot water being less dense, (without steam), will slow the nuclear reaction rate. Denser water = more slowing down of neutrons. (Neutrons must be slowed to "thermal" energies, meaning not energetic, penetrating, to cause fission).  

What happened at Chernobyl was a steam expansion (very rapid, explosion, if you will), followed by dissociation of water into H2 and O2 due to the intense heat, followed immediately by a large H2 detonation. All of that happened in a fraction of a second as reactor power spiked to about 1000% and back down. It came back down essentially because the core had blown itself apart so much a chain reaction could no longer be sustained. Then the graphite fire that lofted millions of Curies of activity (fission products) up into the atmosphere.

Operators not understanding what was happening, compounded the problem and pretty much directly CAUSED the steam explosion through their actions. Several of the actions they took would not even be physically possible on a "western" PWR reactor. The reactor would have automatically shutdown in response.  

Dave

[Kinophile]

2 hours ago, TheVulture said:

The plant in question is already shut down and not producing any electricity for Ukraine's grid, so no major change

@Beleg85 Plus,  the Ukrainian power grid is now fully hooked into the EU grid since, I believe, last Autumn. 

Take a breath,  my friend Trust in Ukraine! 

Edited June 6, 2023 by Kinophile

[Ultradave]

I think I'll stop here. I could talk about this stuff all day  

Bottom line is that it sounds like the reactor plant is safe for the foreseeable future, as long as no one damages that on-site cooling pond/lake.  I'd get concerned if fighting happens around the plant. Previously, Russian commanders locally have shown a dangerous disregard for the hazards of munitions and reactor plants. 

Dave

[Seminole]

1 hour ago, Joe982 said:

Ukraine cut the water supply to Crimea way back in 2014, so water to Crimea is not the issue.

The Russians had restored that water flow at the outset of the invasion:

February 24, 20221:58 PM ESTUpdated a year ago

MOSCOW, Feb 24 (Reuters) - Russian forces restored water flow to a canal linking the Dnieper River in Ukraine to Russian-annexed Crimea, a Russian defence ministry spokesperson said on Thursday, as Russia pressed ahead with a vast military operation against Ukraine.

Ukraine cut off fresh water supply along the canal that had supplied 85% of the peninsula's needs after Moscow annexed Crimea in 2014. The Soviet-era waterway was built to channel water from the Dnieper to arid areas of Ukraine's Kherson region and Crimea.

[Rokko]

9 minutes ago, Ultradave said:

Yes, RBMK (were, I believe none are operating anymore?) are graphite moderated, water cooled. [...]

Out of curiosity, I looked it up. There are still 8 operational, in Smolensk, Kursk and St Petersburg. According to wikipedia, there were modifications after Chernobyl to prevent further similarly catastrophic incidents.

[Ultradave]

Just now, Rokko said:

Out of curiosity, I looked it up. There are still 8 operational, in Smolensk, Kursk and St Petersburg. According to wikipedia, there were modifications after Chernobyl to prevent further similarly catastrophic incidents.

Thanks., I didn't know this.  I'll have to look and see what the modification are.  #1 on my list would be to train operators better. Much better. But i guess they must have made physical changes too.

Dave

[Kinophile]

1 hour ago, Butschi said:

True. [...] Oh well, I guess someone here knows/remembers better.

You're literally quoting the guy who does

Edited June 6, 2023 by Kinophile

[akd]

Looking back to the original drone footage, the area on the left bank side of the turbine halls was not initially breached:

 

[Battlefront.com]

19 minutes ago, Ultradave said:

I think I'll stop here. I could talk about this stuff all day 

I think I can speak for just about everybody here... and all day we'd make a special point of reading everything you wrote

I know that every time the NPP gets brought up I wait to see what you have to say before getting into a tizzy.  I sleep much better.

Steve

[Butschi]

10 minutes ago, Kinophile said:

You're literally quoting the guy who does

I did realize that (from the answer to that, I admit). And damn, now you highlight it, I see that I should have phrased it the way I meant it: that certainly there are people here who know better than me. @Ultradave sorry if that came over in a wrong way.

Edited June 6, 2023 by Butschi

[Centurian52]

5 hours ago, Butschi said:

of course the Russians are perfectly capable of blowing the dam and certainly aren't troubled with too many moral scruples.

That's not evidence, though, and absolutely doesn't rule out catastrophic failure, right?

I mean, we aren't in church here, no need to show faith. I for one will sit back and wait until we know more.

yes

5 hours ago, Bulletpoint said:

we can safely assume as a "working hypothesis" that it was the Russians unless we see proof to the contrary.

also yes