Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[M. Bachmeier]

Does anyone hear have any knowledge about the (pre-satellite) sound detection devices used to detect nuclear testing.

I watched a documentary some time ago, which explained how specific frequencies indicated nuclear as opposed to conventional explosions.

Been unable to find a source on the internet that specifies what frequencies and other specifics are needed to make such a determination.

And yes, it may have bearing on the discussion here.

Any help or reference to link is most welcome.

 

[Zallia]

http://www.telegraph.co.uk/news/wor...9502/Nuclear-meltdown-at-Fukushima-plant.html

Didn't see this posted...

 

[mrcurious]

Why can't they say more specifically which one they are talking about. The one of the refuelling tunnel/entrance on the SW corner? That would be most likely from their plan, I guess.

I believe it was the double door between the reactor building and the turbine building.

 

[SredniVashtar]

Sorry if this is old news, just read about it on the BBC website:
http://www.bbc.co.uk/news/world-asia-pacific-13374153

Setbacks at Japan nuclear plant

[...] a spokesman for the power giant said when a faulty gauge had been repaired, it showed water levels in the pressure vessel 5m (16ft) below the level needed to cover fuel rods.
"All the fuel is unprotected at this point and the water levels are below that," said Junichi Matsumoto.
[...] "However temperatures in the reactor pressure vessel have cooled to 100 to 120 degrees so we have come to the conclusion that the fuel mass... is actually not at the proper levels but somewhat below that or even possibly at the bottom of the vessel."
He said there was likely to be a large leak in the pressure vessel, possibly caused by the fallen fuel.
"As for a meltdown, it is certain that it has crumbled and the fuel is located at the bottom (of the vessel)," he added.​

Is this new news (at least from the 'official' point of view) or is it something already well known?

(I see now that Zallia posted the news two messages before mine :-/ )

 

[mrcurious]

Based on this new information from #1, can anyone explain the supposed pressure drop when tepco began filling the PCV and subsequent decision to slow the water fill so as not to create a possible explosive situation where the pressure inside was lower than outside causing oxygen to be introduced in the PVC?

 

[AntonL]

Based on this new information from #1, can anyone explain the supposed pressure drop when tepco began filling the PCV and subsequent decision to slow the water fill so as not to create a possible explosive situation where the pressure inside was lower than outside causing oxygen to be introduced in the PVC?

Theater, Tepco demonstration that they are on top of the situation, but every good suspense thrillers has intriguing turns, this is just one of them.

Sorrry, one of the many Fukushima mysteries that we are not going to solve.

 

[zapperzero]

Sorrry, one of the many Fukushima mysteries that we are not going to solve.

FWIW, I do have a theory: There is core on the RPV floor, producing a massive amount of steam. Water is escaping, through cracks below the corium level. Steam stays in the RPV, under some pressure. When you introduce more water, the steam cools down so the pressure drops.

It's stupid, but it's all I could come up with (I'm having a long day).

 

[jim hardy]

out of synch message here... to unlurk
you mentioned you were curious about a reported radiation increase at time of u-3 mishap?

here's logsheet of readings taken (by hand?), from a 'monitoring car' (with handheld instruments?) according to note at top of page. i guess with so much chaos and no electric power they had to resort to manual data collection? All things considered i'd say they did a good job.

http://www.tepco.co.jp/en/nu/monitoring/11031401a.pdf

Anyhow, i hope the datasheet is of interest to you and this is not a repeat.

 

[unlurk]

message to unlurk

Thanks for the followup.

That isn't any help although that data is interesting in itself.

What I am wondering about is a short spike of gamma radiation which occurred that morning.

The data at the link you gave was the readings at different locations around the plant. The spike of gamma radiation I assume would have maxed out their instrument and when they reset or re-caled it and tried again everything would have been normal again.

 

[clancy688]

http://www.telegraph.co.uk/news/wor...9502/Nuclear-meltdown-at-Fukushima-plant.html

Didn't see this posted...

Engineers from the Tokyo Electric Power company (Tepco) entered the No.1 reactor at the end of last week for the first time and saw the top five feet or so of the core's 13ft-long fuel rods had been exposed to the air and melted down.

That's a good laugh. TEPCO went into a nuclear plant which suffered a meltdown only two months ago, unscrewed the RPV cap, looked into it, saw the mess, screwed it back on and reported what they saw.

 

[fluutekies]

Cryptome has some more hi-res pictures from the series of 70:
http://cryptome.org/eyeball/daiichi-npp15/daiichi-photos15.htm

 

[clancy688]

TEPCO official at press conference:

"The pressure gauge for the Containment Vessel is working, but we cannot properly measure the water level inside the Containment Vessel. Therefore, we do not know where the water level is."

"We are trying to figure that out. In the initial stage when the reactor core was still hot, the water might have been evaporated and escaped from the Containment Vessel. But now, the reactor temperature is between 100 to 120 degrees Celsius, so the water would remain water. We are assuming most of the water escaped the Containment Vessel into the surrounding reactor building. However, there is no water in the northwest corner of the basement of the reactor building, as far as we can see by the camera. We don't know where the water has gone. Possibly, it may have gone to the reactor building, the turbine building, or the waste disposal facility. But we haven't identify it yet."

http://ex-skf.blogspot.com/2011/05/from-tepco-presser-may-12-am-part-1-we.html

 

[jlduh]

Sorry if this is old news, just read about it on the BBC website:
http://www.bbc.co.uk/news/world-asia-pacific-13374153

Setbacks at Japan nuclear plant

[...] a spokesman for the power giant said when a faulty gauge had been repaired, it showed water levels in the pressure vessel 5m (16ft) below the level needed to cover fuel rods.
"All the fuel is unprotected at this point and the water levels are below that," said Junichi Matsumoto.
[...] "However temperatures in the reactor pressure vessel have cooled to 100 to 120 degrees so we have come to the conclusion that the fuel mass... is actually not at the proper levels but somewhat below that or even possibly at the bottom of the vessel."
He said there was likely to be a large leak in the pressure vessel, possibly caused by the fallen fuel.
"As for a meltdown, it is certain that it has crumbled and the fuel is located at the bottom (of the vessel)," he added.​

Is this new news (at least from the 'official' point of view) or is it something already well known?

(I see now that Zallia posted the news two messages before mine :-/ )

Hi, look at the previous pages on this thread, we've been commenting this here today (some articles reported it through various statements, not exactly the same wording, but the event we are talking about is the same).

 

[unlurk]

Brought it up just a few pages back, too (and before that, 50 pages or so back). Just questioning what it means, really. I can not see how definite answers on that can be given with the little we know.

We don't really know where the bunker is situated and how he is shielded, or do we? We only know that the burst was supposedly 12x higher than normal (measured by humans on a personal counter/dosimeter/stationary or handheld counter?).

We also don't know if there were any neutron detectors running and if there's any data on that. Due to the power outage no stationary sensors were online. We don't know the exact state of #3 and the SFP during the explosion which could explain the gamma burst xD.

A gamma burst would suggest criticality before/during the explosion. I could think about other explanations, but these sound crank to me so I rather not post them. Maybe I'm missing something really obvious though.

I would be interested in your ideas and please don't be worried if they might sound "crank" we need more brainstorming going on here IMO. This event is not a charted process. We are pioneering, we are trying to unravel the details of what happened when four complex systems went out of control and into cascades of unplanned behavior.

Many people in the NP industry are very procedure oriented by nature, they wouldn't have fit in if they weren't. Breaking out of the box can be uncomfortable I understand. But it will be necessary to explore all possibilities if we want to uncover the things which we have never been "trained" on and have no intuitive way of knowing.

 

[zapperzero]

Thanks for the followup.

That isn't any help although that data is interesting in itself.

What I am wondering about is a short spike of gamma radiation which occurred that morning.

I see 0.2 Sv/h recorded near Unit 3 at 10:40 AM. It's not what you're looking for probably, because there's no neutrons reported (criticality makes a lot of those, no?).

 

[|Fred]

Cryptome has some more hi-res pictures from the series of 70:
http://cryptome.org/eyeball/daiichi-npp15/daiichi-photos15.htm

They are the same resampled... most image viewer or browser can do the same one the fly. Not quite the same as hi-res

 

[~kujala~]

http://english.kyodonews.jp/news/2011/05/90715.html

Tokyo Electric Power Co., the operator of the crippled Fukushima Daiichi nuclear power plant, revealed Thursday that holes had been created by melted nuclear fuel at the bottom of the No. 1 reactor's pressure vessel.

The company said it has found multiple holes adding up to several centimeters in welded piping.

I am wondering could this mean that some of the melted fuel has already found its way out of the RPV...?

 

[Dmytry]

I would be interested in your ideas and please don't be worried if they might sound "crank" we need more brainstorming going on here IMO.

Suppose the heavy stuff fell into the spent fuel pool, breaking open the tubes, leading to release of a lot of Kr-85, which later dissipated.
Without the data on how well that bunker is shielded, can't really tell if that's even within right order of magnitude to be an explanation.

I still believe that the #3 had explosive venting of the giant volume of steam and hydrogen from the containment vessel (containment vessel burped), which explains the hollywood-esque explosion. However, it is hard to explain why the hole (max damage) in the roof grid is right over spent fuel pool. Maybe after initial explosion, something heavy fell into spent fuel pool, distorting the geometry, causing criticality, and secondary explosion.

 

[unlurk]

not what you're looking for probably

No, what I am wondering about is a reported burst of gamma energy in a Tepco "bunker" which was said to have been shielded by concrete and a layer of dirt.

The only radiation that could have gotten into a bunker like that would have been gamma radiation. But they didn't have a neutron counter set up at the time (apparently at the whole site) so this just remains a stray piece of information.


The reason I am interested in it is that it could be seen as supporting my hypothesis that the SFP at #3 went critical at that time. In the reciprocal, if it could have been proven that there was no neutron burst at that time, my hypothesis would be dis proven.

But that is not the case.

 

[unlurk]

Suppose the heavy stuff fell into the spent fuel pool, breaking open the tubes, leading to release of a lot of Kr-85, which later dissipated.
Without the data on how well that bunker is shielded, can't really tell if that's even within right order of magnitude to be an explanation.

I still believe that the #3 had explosive venting of the steam and hydrogen from the containment vessel (containment vessel burped), which explains the hollywood-esque explosion..

Why would a release of Krypton cause a gamma burst?

 

[Dmytry]

Why would a release of Krypton cause a gamma burst?

ahh sorry, Kr-85 this one primarily decays by beta. Got it mixed up with other isotopes that have significant fraction of gamma decay. (edit: xe-133 but that one has half life 5 days so there wouldn't be any in spent fuel pool)
Radioactive gas that decays by gamma, can give you relatively short gamma spike (before getting blown off by wind).
So i guess this is ruled out. The non-gaseous fission products would fall out some and wouldn't disappear so rapidly.

 

[unlurk]

I still believe that the #3 had explosive venting of the giant volume of steam and hydrogen from the containment vessel (containment vessel burped), which explains the hollywood-esque explosion.

Units 1,2 and 4 had hydrogen explosions which released nowhere near the energy seen in the #3 blast.

I agree that there was a burp from the drywell, but that release in itself would not have been a hugely energetic event but it ejected a quantity of oxygen starved hydrogen into the area just above the containment lid.

The initial blast which we can see as a ball of flame exiting the south face of the #3 building in the first tenth of a second or so would have had to have been a result of the released (heated) hydrogen hitting the outside air.

The hollywood-esque explosion was a secondary event. That seems pretty clear.

However, it is hard to explain why the hole (max damage) in the roof grid is right over spent fuel pool. Maybe after initial explosion, something heavy fell into spent fuel pool, distorting the geometry, causing criticality, and secondary explosion.

Not hard to explain if you accept that the blast originated from the SFP.

This would also tie in with the contaminated material around the site and as far as 30 kilometers north west of the site - that material came from the SFP.

The reactor remained intact at that point in fact it still is intact. The radiation had to have come from somewhere.

 

[mrcurious]

There has been a couple references to equipment falling into the #3SFP and breaking the fuel rods but I don't see it. They look pretty well set in their assemblies, they weren't laying crossways in the pool and even heavy pieces would lose a considerable amount of their weight in water. Are they that brittle?

If this is a reason to explain radioactive leakage, I think the more likely answer is they were damaged in the explosion...if not partially melted prior to that.

 

[unlurk]

I am wondering could this mean that some of the melted fuel has already found its way out of the RPV...?

I am of the opinion that that possibility may not be such a big deal.


The lesson was learned at Chernobyl that there is no such thing as "China Syndrome."

The Russians were so worried about that that they dug a tunnel under the core location intending to freeze it with nitrogen. But in the end, they realized that the corium was stopped by the thick concrete under the "core." They filled their tunnel with concrete (probably to save face) and left the corium to its own to decay the heat.


Here at Fukushima the reactors have been shut down for two months already, we are past the critical point IMO.

 

[clancy688]

http://english.kyodonews.jp/news/2011/05/90715.html
I am wondering could this mean that some of the melted fuel has already found its way out of the RPV...?

There was this TEPCO damage estimation regarding Drywell and Wetwell Radiation. As for Unit 1: 45% damage in wetwell, 10% damage in drywell, 55% damage overall.
While this doesn't show if the fuel rods have only ruptured or indeed molten down, newest informations (water well below the fuel rods) let us in fact conclude that there was massive core melting going on in RPV 1.

So... what about that theory:

45% Corium in RPV
10% Corium in Drywell
45% Corium on its way through or somewhere in the ground below Unit 1 (since there's a major leakage of water from the Containment which we DON'T see - that leaves, at least in my opinion, only the "down" direction as path for the water)

 

[unlurk]

There has been a couple references to equipment falling into the #3SFP and breaking the fuel rods but I don't see it. They look pretty well set in their assemblies, they weren't laying crossways in the pool and even heavy pieces would lose a considerable amount of their weight in water. Are they that brittle?

If this is a reason to explain radioactive leakage, I think the more likely answer is they were damaged in the explosion...if not partially melted prior to that.

Do you have a link to a picture of the FP at unit 3 showing an orderly scene?

 

[unlurk]

There was this TEPCO damage estimation regarding Drywell and Wetwell Radiation. As for Unit 1: 45% damage in wetwell, 10% damage in drywell, 55% damage overall.
While this doesn't show if the fuel rods have only ruptured or indeed molten down, newest informations (water well below the fuel rods) let us in fact conclude that there was massive core melting going on in RPV 1.

So... what about that theory:

45% Corium in RPV
10% Corium in Drywell
45% Corium on its way through or somewhere in the ground below Unit 1 (since there's a major leakage of water from the Containment which we DON'T see - that leaves, at least in my opinion, only the "down" direction as path for the water)

What gives you any reason to suppose that the corium has gotten past the drywell floor?

 

[clancy688]

What gives you any reason to suppose that the corium has gotten past the drywell floor?

Water leakage.

TEPCO is pumping at 6 m³/h water for weeks now. And yet they discovered yesterday that the actual water level is 1m below the fuel rods. That must mean that there's some kind of big leak in the RPV, leading right into the containment.
But now there's a problem as well - TEPCO reported that there's not enough water in the containment (hence drywell) to make up for all the water which disappeared. I rule water release by steam out since we haven't seen ANY pictures of steam erupting from Unit 1.
So every day pretty big amounts of water simply disappeared from Unit 1. As for Units 2 and 3, the water was found in the basement, or in the turbine building, or in some pits...
But not for Unit 1. That leaves, at least in my opinion, only one possible way left - down. A hole right through the containment going deep into the ground. And there's only one thing in a nuclear reactor which could create such a hole.

 

[elektrownik]

They injecting 8m^3/h science few days

 

[unlurk]

Water leakage.

TEPCO is pumping at 6 m³/h water for weeks now. And yet they discovered yesterday that the actual water level is 1m below the fuel rods. That must mean that there's some kind of big leak in the RPV, leading right into the containment.
But now there's a problem as well - TEPCO reported, that there's not enough water in the containment (hence drywell) to make up for all the water which disappeared. I rule water release by steam out since we haven't seen ANY pictures of steam erupting from Unit 1.
So every day pretty big amounts of water simply disappeared from Unit 1. As for Units 2 and 3, the water was found in the basement, or in the turbine building, or in some pits...
But not for Unit 1. That leaves, at least in my opinion, only one possible way left - down. A hole right through the containment going deep into the ground. And there's only one thing in a nuclear reactor which could create such a hole.

First off, there are no more fuel rods.

What is obvious to me is that the water they have pumped in has found its own way(s) out to the ground and the ocean. There are any number of cracks in the foundation and flooring (due to the quake and the aftershocks) of the #3 building but it would be an amazing stroke of bad luck to have one of those cracks to be located directly under the corium.

I don't see any reason to consider that likely, and certainly not probable.

 

[clancy688]

They injecting 8m^3/h science few days

Makes the leakage even worse... :p http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/flow-un1.txt <-- Stolfis plots.

It seems as if they were injecting only 2 m³/h for over 10 days... as I stated before, you probably need 7-10 m³/h to cool a 1500 MWt core during the first ten days.

First off, there are no more fuel rods.

Of course not. Next time I'll write "former fuel rods". Or do you have a better idea to report the exact water height in the RPV?

As for the cracks:

As I said, in Unit 2 and 3 they know where the water went. Through all of these earthquake and tsunami related cracks and ruptures. As for Unit 1, they have no clue.
That's why I say it's probably a hole created by Corium going straight down into negative y direction (dunno how to better describe it).
It's just a theory. But it seems logical at least for me. ;)
Corium penetrated the RPV. So why shouldn't it be possible for it to penetrate the concrete of the containment bottom as well? If it wasn't, there would be no reason to develop core catcher.

 

[unlurk]

a better idea to report the exact water height in the RPV?

There are some things which I can never make any sense of.


One of them is concern about the water level in the RPV.

The RPV is breached somewhere; find that somewhere and you will find the water level.

But for Tepco to be clinging to some ancient historical method of describing water levels seems a bit foolish to me.

 

[bytepirate]

They must have. Water in Unit 1 has been disappearing. TEPCO keeps pumping and pumping and today they discover that it's 1 m below the fuel bottom.
Either there are low lying leaks in both RPV and containment through which the water escapes and the pressure sensors are sending bogus data, or some kind of magic is letting that water disappear.
Water leak AND rising pressure together is impossible. But water leakage has been confirmed, so the pressure readings must be wrong.

Water leak AND rising pressure together is possible as long as more water is going in, than out.

thats not my explanation of what happens in #1, just a general remark ;-)

 

[mrcurious]

Do you have a link to a picture of the FP at unit 3 showing an orderly scene?

Of course not, the pics were quite disorderly. But how does a disorderly scene above the FR assemblies imply fuel rod damage? The inference is stuff fell into the pool and settled on top of the FRA.

 

[Bandit127]

A suggestion and a question...

I suggest that the exact water level in Unit 1 is actually somewhere between "1m below the fuel rods" and the water table. Tepco cannot be more precise than this, and I don't think we can be either.

My question probably has an obvious answer - but it eludes me. Assuming that the core has migrated, why isn't it in the torus? I though part of its function was to catch a molten core...

A sad day for nuclear engineering and a really bad day at work for the Tepco Engineers. There was i thinking that I has a bad day at work...