Japan Earthquake: Nuclear Plants at Fukushima Daiichi

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The Fukushima Daiichi nuclear plant is facing significant challenges following the earthquake, with reports indicating that reactor pressure has reached dangerous levels, potentially 2.1 times capacity. TEPCO has lost control of pressure at a second unit, raising concerns about safety and management accountability. The reactor is currently off but continues to produce decay heat, necessitating cooling to prevent a meltdown. There are conflicting reports about an explosion, with indications that it may have originated from a buildup of hydrogen around the containment vessel. The situation remains serious, and TEPCO plans to flood the containment vessel with seawater as a cooling measure.
  • #9,841
I think they used sensors on these poles to check out for radiation before entering the area.
 
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  • #9,842


DR13 said:
Is there any real chance at a meltdown or is that just the typical media hype?

It's funny, because I saw the media as playing down the entire thing. They never even tried to get independent measurements, which would have made for a huge story. Instead they pretty much bought the official nonsense, and never lifted a finger to find out anything firsthand.

Not even when the US military diverted ships from the area.
 
  • #9,843


robinson said:
It's funny, because I saw the media as playing down the entire thing. They never even tried to get independent measurements, which would have made for a huge story. Instead they pretty much bought the official nonsense, and never lifted a finger to find out anything firsthand.

Not even when the US military diverted ships from the area.
I think the media lost its interest when the land side measurements of Greenpeace and a few others were in accordance with those from the government (even though the interpretation of those measurements differed quite a bit).
 
  • #9,844
Borek said:
I think they used sensors on these poles to check out for radiation before entering the area.

It seemed to me that they were very cautiously trying to determine the flooding level in the lower regions of the building- and once they found the upper extent of the water, they probably beat one hell of a hasty retreat. Seeing that greenish coloration begin one tread down at the lowest stairwell area they got down to (at 1:38) looked like the water level to me, and I'd have to believe that said water would be more than a little radioactive.

Those folks are very, very brave.
 
  • #9,845
They are using 40mil poly pond liner (40mil = 1mm). If 40mil poly held up to the sorts of winds that are common around an ocean, then yacht sails would be a heck of a lot cheaper! One uses poly on greenhouses because it is cheap and easy to fix when it blows out -- in fact one of the advantages is that it does blow out, which means that your greenhouse frame stays intact. Poly is not a recommended building material for windows or walls or even really trans-pacific shipping purposes. (Steel containers are used for that when possible.)

I want this problem to be solved; if Gunderson is to be believed then I'm breathing the same hot particles that those of you who live in Tokyo do (albeit not quite as many.) But this approach looks to me like an upper-management obession rather than an engineering fix. I'm willing to be wrong on this, but the snippet in the video of the exec showing an autocad presentation with little square walls magically hopping on top of each other didn't give me much confidence about the engineering thought that went into this idea.

If the structure could be constructed and did in fact hold up and was airtight (which I consider doubtful), then I question the wisdom of adding sails to damaged buildings of unknown structural integrity in a location that is prone to typhoons. If that isn't enough, then realize that they are vaporizing 1300 gallons/hr in reactor #1 plus an unspecified amount of water in the SFP. That is over 8000 cubic meters of vapor per hour that needs to be dealt with to keep the bag from turning into a blimp.

Add to the mix the fact that we are still arguing why reactor #4 exploded and you can see why I am doubtful about the wisdom of putting all of the reactor's work product into a plastic bag and blowing it out with electric fans.

If they get the plan to work, then I also question how they plan to approach the reactor now that they have a 1300 gph rainstorm of radioactive water flowing down the inside of the bag -- assuming that the steam doesn't just melt the poly straight away. It is not only water that would be contained, but some percentage of the heat; and the temps in that reactor building are significant.

I think that this is a plan that looks good to an engineer who hasn't worked much with poly sheets...
 
  • #9,846
Borek said:
Are you sure they are properly described?

They were improperly described - it was past my bedtime and I just cut and paste the descriptions from TEPCO's website.

I have now tried to correct the descriptions as well as I can.

The 4th video is corrupt for me too - only 16 s long.

I will leave them up there and use the page if further zipped videos appear on Tepco's site. Please let me know if you want any videos unzipping and reposting.

P.S. If it was Solidworks that was used to generate the CG animations then good skills from the engineer(s) involved. A lot of work went into that - possibly hundreds of man-hours, certainly tens.
 
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  • #9,847
The geology discussion could use it's own thread.
 
  • #9,848
Orcas George said:
They are using 40mil poly pond liner (40mil = 1mm). If 40mil poly held up to the sorts of winds that are common around an ocean, then yacht sails would be a heck of a lot cheaper! One uses poly on greenhouses because it is cheap and easy to fix when it blows out -- in fact one of the advantages is that it does blow out, which means that your greenhouse frame stays intact. Poly is not a recommended building material for windows or walls or even really trans-pacific shipping purposes. (Steel containers are used for that when possible.)

I want this problem to be solved; if Gunderson is to be believed then I'm breathing the same hot particles that those of you who live in Tokyo do (albeit not quite as many.) But this approach looks to me like an upper-management obession rather than an engineering fix. I'm willing to be wrong on this, but the snippet in the video of the exec showing an autocad presentation with little square walls magically hopping on top of each other didn't give me much confidence about the engineering thought that went into this idea.

If the structure could be constructed and did in fact hold up and was airtight (which I consider doubtful), then I question the wisdom of adding sails to damaged buildings of unknown structural integrity in a location that is prone to typhoons. If that isn't enough, then realize that they are vaporizing 1300 gallons/hr in reactor #1 plus an unspecified amount of water in the SFP. That is over 8000 cubic meters of vapor per hour that needs to be dealt with to keep the bag from turning into a blimp.

Add to the mix the fact that we are still arguing why reactor #4 exploded and you can see why I am doubtful about the wisdom of putting all of the reactor's work product into a plastic bag and blowing it out with electric fans.

If they get the plan to work, then I also question how they plan to approach the reactor now that they have a 1300 gph rainstorm of radioactive water flowing down the inside of the bag -- assuming that the steam doesn't just melt the poly straight away. It is not only water that would be contained, but some percentage of the heat; and the temps in that reactor building are significant.

I think that this is a plan that looks good to an engineer who hasn't worked much with poly sheets...

I would appreciate it if you could please recommend the soulution that you would use or at a minimun a solution to what you precive as the problems with the design. I agree that there are many "what ifs" here, you seem to have spent sometime on this problem so what direction, and time frame to do it would you take?
 
  • #9,849
Orcas George said:
I think that this is a plan that looks good to an engineer who hasn't worked much with poly sheets...

Or walked into a greenhouse in the middle of Summer to water the plants.

For reference, the yield strength of polyethylene is about 4,000 psi or about 25 MPa. About 1/3 that of copper (at 70 MPa).

So, a 1 mm square string could support ~2.5 kg. Or a 25 mm x 1 mm strip could support ~62.5 kg.

We will wait and see, but I am optimistic that it isn't in tatters by this time next year.
 
  • #9,850
maddog1964 said:
I would appreciate it if you could please recommend the soulution that you would use or at a minimun a solution to what you precive as the problems with the design. I agree that there are many "what ifs" here, you seem to have spent sometime on this problem so what direction, and time frame to do it would you take?


Afaik, all larger fabric covered structures are either largely self supported, by increased internal air pressure, or they use a very robust reenforced membrane, with tensioner webbing incorporated into the fabric.
None use flat panels of fabric, which have no strength against perpendicular loads, nor do they use a right angle based framework, because that is just an invitation for eddies and turbulence creating stresses at odd angles, which the poly skin is not well suited for.
The flat frame structure is surely the easiest to put up, especially as there is not enough room to accommodate individual bubbles because the reactors are so close together. Also, a light framework that is easy to erect and is without big foundations probably cannot support much more than a film wall. TEPCO does say the building is temporary, which it is perhaps even more so than might be wished.
Imho, it will at least give TEPCO a dry run to see what the problems posed by a closed containment will be,
but otherwise it seems impractical.
 
  • #9,851
Doh. Taken from the end of June 15th TEPCO status update...

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110615_02-e.pdf

At approximately 11:05 am on June 16, we confirmed that one employee from a partner company was smoking without a full mask when he was assembling a crane at the shallow draft quay as preparation work for an installation of a cover for the reactor building of Unit 1. Each density of radioactive materials of particulate and iodine in the air at the site was below measurable limit.
Today as a result of dose evaluation for the employee internal exposure dose was 0.13 mSv and external exposure dose was 0.24 mSv.
 
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  • #9,852
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  • #9,853
zapperzero said:
But how does all that make it necessary for a second explosion to have happened? There's any number of structures in there that could have shaped the hydrogen blast.

Isn't there a doubt that not only two explosions happened?
It seems so obvious that there were multiple explosions.

Just look at this http://www.tepco.co.jp/en/news/110311/images/110611_05.jpg" from floor 4 of RB#4. (please open in a separate tab, big size!)
Look at the 480V distribution you see in the lower right.

You immediately see that there is something wrong with it.
For example. the covers are blown off. Apparently from the inside!

But - as an electr(on)ics engineer will recognize immediately, the whole thing does not look like an usual electric explosion, It just looks different.

The electric parts do not show the usual damage that happens when a panel blows up due shorts etc. There is no typical sooting that you are used to see in such cases, for example. Cable damage is not recognizable, except for some possible overheating of the white line, but that has probably been at a former occasion and not at this incident, as the corrective measures indicate.

As said above, the protection sheets of the electric distribution appear to have been blown off from inward. The typical bending you can expect in case of external explosion damage is totally missing. In fact, the bending you can see indicates an internal explosion.

So it seemed completely obvious to me that this deformation of the distribution box was due to a secondary, tertiary etc. hydrogen explosion.

Somebody mentioned this picture several pages ago in this thread and asked for comments.
I didn't answer, because I thought that this would be obvious even for a dumbass like me that there have been multiple explosions.
And to me, this picture does not prove much except just that there were multiple explosions...

Can be there any doubt that there was a chain-reaction of explosions?
 
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  • #9,854
etudiant said:
Afaik, all larger fabric covered structures are either largely self supported, by increased internal air pressure, or they use a very robust reenforced membrane, with tensioner webbing incorporated into the fabric.
None use flat panels of fabric, which have no strength against perpendicular loads, nor do they use a right angle based framework, because that is just an invitation for eddies and turbulence creating stresses at odd angles, which the poly skin is not well suited for.
The flat frame structure is surely the easiest to put up, especially as there is not enough room to accommodate individual bubbles because the reactors are so close together. Also, a light framework that is easy to erect and is without big foundations probably cannot support much more than a film wall. TEPCO does say the building is temporary, which it is perhaps even more so than might be wished.
Imho, it will at least give TEPCO a dry run to see what the problems posed by a closed containment will be,
but otherwise it seems impractical.

I appreciate you imput and suggestion as I also see many foceable problems, but what I also see on the thread is very detailed summaries as to what will not work and why, but very few answers to the problems. That would lead me to believe that the answers are not quite as simple and the time required to perform them such. So what are the solutions and what time frame is required to perform them. I do have thougths on the process but do not suggest them as I do not have enought site information to understand what all is involved. But I also do not suggest what won't work.

It would be nice to see some solutions offered to as what would work and how to approch it. There maybe a thread that is all ready disscusing this, if so could you please direct me. I do not know how to navigate this forum, usually just read.
 
  • #9,855
Atomfritz said:
As said above, the protection sheets of the electric distribution appear to have been blown off from inward. The typical bending you can expect in case of external explosion damage is totally missing. In fact, the bending you can see indicates an internal explosion.
So the hydrogen explosion had to start somewhere. Maybe a spark inside your electrical distribution box?
 
  • #9,856
biffvernon said:
So the hydrogen explosion had to start somewhere. Maybe a spark inside your electrical distribution box?

There was no electricity at the site at the time of explosion, that's why reactors went out of control.
 
  • #9,857
maddog1964 said:
I appreciate you imput and suggestion as I also see many foceable problems, but what I also see on the thread is very detailed summaries as to what will not work and why, but very few answers to the problems. That would lead me to believe that the answers are not quite as simple and the time required to perform them such. So what are the solutions and what time frame is required to perform them. I do have thougths on the process but do not suggest them as I do not have enought site information to understand what all is involved. But I also do not suggest what won't work.

It would be nice to see some solutions offered to as what would work and how to approch it. There maybe a thread that is all ready disscusing this, if so could you please direct me. I do not know how to navigate this forum, usually just read.

The site is so crowded and compromised that the whole thing is a proverbial 'can of worms'.
For that, the only solution is a bigger can, one large enough to cover all 4 reactors.
The Chernobyl sarcophagus replacement, sort of a shed on tracks that gets moved over the reactors, seems the most plausible approach, but that is not a 2011 or even 2012 solution.
It may be worth starting a thread on this specific topic, as it poses very interesting issues.
 
  • #9,858
Atomfritz said:
Isn't there a doubt that not only two explosions happened?
It seems so obvious that there were multiple explosions.

Just look at this http://www.tepco.co.jp/en/news/110311/images/110611_05.jpg" from floor 4 of RB#4. (please open in a separate tab, big size!)
Look at the 480V distribution you see in the lower right.

You immediately see that there is something wrong with it.
For example. the covers are blown off. Apparently from the inside!

But - as an electr(on)ics engineer will recognize immediately, the whole thing does not look like an usual electric explosion, It just looks different.

The electric parts do not show the usual damage that happens when a panel blows up due shorts etc. There is no typical sooting that you are used to see in such cases, for example. Cable damage is not recognizable, except for some possible overheating of the white line, but that has probably been at a former occasion and not at this incident, as the corrective measures indicate.

As said above, the protection sheets of the electric distribution appear to have been blown off from inward. The typical bending you can expect in case of external explosion damage is totally missing. In fact, the bending you can see indicates an internal explosion.

So it seemed completely obvious to me that this deformation of the distribution box was due to a secondary, tertiary etc. hydrogen explosion.

Somebody mentioned this picture several pages ago in this thread and asked for comments.
I didn't answer, because I thought that this would be obvious even for a dumbass like me that there have been multiple explosions.
And to me, this picture does not prove much except just that there were multiple explosions...

Can be there any doubt that there was a chain-reaction of explosions?

How did this conversation jump from unit 3 to unit 4?

This string started out with me hypothesizing that there had to have been two explosions in the unit 3 event. Now the discussion is apparently about unit 4, but I can't see where the unit 4 subject was introduced.

BTW
The vertical blast at unit 3 was definitely not "hot air rising": the concrete chunks which are seen falling out of the cloud didn't just levitate themselves up there.
 
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  • #9,859
Looks like we will have closed loop cooling of Unit 3's SFP by the end of June. http://www.tepco.co.jp/en/press/corp-com/release/11061511-e.html"

I understand 'flow glass' to mean a visual flow indicator.

The 'hot' side will have desalination but no other clean up installed, so it will remain radiologically hot. Deoxidised make up water will be added along with 'chemicals' to prevent corrosion.

Remote observation will be installed so the operation of the plant can be monitored from the anti earthquake buliding.

They expect the temperature to decrese to 65°C after 1.6 days. Despite the latest data that I can find being a repeat of data taken on May 8th (from http://www.nisa.meti.go.jp/english/press/2011/06/en20110615-3-2.pdf" ) this implies a precise knowledge of the current temperature.

Another step in the right direction anyway. Good.
 
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  • #9,860
Borek said:
biffvernon said:
So the hydrogen explosion had to start somewhere. Maybe a spark inside your electrical distribution box?
There was no electricity at the site at the time of explosion, that's why reactors went out of control.
Yes, there was no electricity at that time.
Not inconsistent with the observation of nothing what suggests an electrical explosion.
But - the outward bending of the electric box suggests that there was an -at least secondary- explosion.
In fact, the photo evidence quite excludes that the electric distribution was the source of the explosion chain. Just look the paint remains, this shows that the panel must have exploded after some other (way bigger) explosion in the room.
But, consider how much time hydrogen had time to accumulate in various rooms that were quite well isolated together.
So I think we might have to deal with several explosions in very short sequence.

Quim said:
How did this conversation jump from unit 3 to unit 4?

This string started out with me hypothesizing that there had to have been two explosions in the unit 3 event. Now the discussion is apparently about unit 4, but I can't see where the unit 4 subject was introduced.
I think there is no basic difference between #3 and #4.
Many (almost) closed/insulated rooms that had sufficient time to build up different explosive H concentrations.
Just the explosion daisy chain was different.
So we can look at #4 and learn.

Quim said:
The vertical blast at unit 3 was definitely not "hot air rising": the concrete chunks which are seen falling out of the cloud didn't just levitate themselves up there.
I agree with you. The thing I just wonder about is what explosion was directed upwards. Explosion number what?
 
  • #9,861
biffvernon said:
So the hydrogen explosion had to start somewhere. Maybe a spark inside your electrical distribution box?

The power had been off for hours. I'm guessing that the only power was DC to relay systems and safety-critical valve acutators. But, if lots of hydrogen is wafting around, it would tend to get inside all spaces that were not hermetically sealed, and an external explosion could then also trigger an explosion inside these spaces.

Jon
 
  • #9,862


DR13 said:
Is there any real chance at a meltdown or is that just the typical media hype?

Meltdown does not have a distinct definition but I think fuzzy as this concept may be a good case can be made that there is no reason to worry about a meltdown since the dreadful has already happened.
 
  • #9,863
Atomfritz said:
The thing I just wonder about is what explosion was directed upwards. Explosion number what?
I don't understand your confusion.
Unit 3 exploded the day before unit 4, so there should be no confusion there.
 
  • #9,864
westfield said:
No, it just means the tent will be on fire twice a week.

If not, maybe the mystery of smoke fog or water vapor will be solved. Fog doesn't make a good ignition source.
 
  • #9,865
Quim said:
I don't understand your confusion.
Unit 3 exploded the day before unit 4, so there should be no confusion there.

You don't understand me.

We have no video evidence of the rb#4 explosion.
But does this mean that it was less spectacular than the #3 one?
And, does this really matter?

#1, #3 and #4 only hicced.
But #2 did more... it burped... it even... maybe sh*t. (please excuse the graphic language ;), I just got inspired by the japanese Nuclear Boy ).
Shouldn't we more look into what really happens/happened there in this so-little-mentioned reactor #2?
 
  • #9,866
Atomfritz said:
You don't understand me.
I sure don't understand you.
You posted this question which was about unit#3.
Atomfritz said:
I agree with you. The thing I just wonder about is what explosion was directed upwards. Explosion number what?
Now you are jumping to #4 then #2.
Atomfritz said:
We have no video evidence of the rb#4 explosion.
But does this mean that it was less spectacular than the #3 one?
And, does this really matter?
#1, #3 and #4 only hicced.
But #2 did more... it burped... it even... maybe sh*t. (please excuse the graphic language ;), I just got inspired by the japanese Nuclear Boy ).
Shouldn't we more look into what really happens/happened there in this so-little-mentioned reactor #2?
I don't detect a coherent thought train in all that. Are you trying to obfuscate the issues?
 
  • #9,867
Quim said:
I sure don't understand you.
You posted this question which was about unit#3.

Now you are jumping to #4 then #2.

I don't detect a coherent thought train in all that. Are you trying to obfuscate the issues?

Is it really relevant to care about what explosion sequence causes what effects?
Isn't this more a fireworker's topic?

Doesn't this discussion about kaboom effects distract from the real problem, to understand what happened at reactor #2 so that there a containment breach occurred?

Isn't it more important to learn what was the cause of this breach and the releases, to be able to avoid such in future?
 
  • #9,868
Atomfritz said:
Is it really relevant to care about what explosion sequence causes what effects?
Isn't this more a fireworker's topic?

Doesn't this discussion about kaboom effects distract from the real problem, to understand what happened at reactor #2 so that there a containment breach occurred?

Isn't it more important to learn what was the cause of this breach and the releases, to be able to avoid such in future?
So you were trying to obfuscate the issue.
That's what I thought.

IMO finding the source of the vectored explosion of the #3 unit is one of the most interesting details of the Fukushima event(s.)

And how do you propose to investigate the source of the explosion in unit 2 when you have no visual information whatsoever and Tepco is laying down a fogscreen about events there?
 
  • #9,869
Quim said:
And how do you propose to investigate the source of the explosion in unit 2 when you have no visual information whatsoever and Tepco is laying down a fogscreen about events there?

C137 release data for Units 1, 2 and 3:

Unit 1: 5.9E14
Unit 2: 1.4E16
Unit 3: 7.1E14

Official report, attachement IV-2, page 7.

The contamination outside the plant is nearly entirely the fault of Unit 2. Unit 1 and 3 may have been eyecandy, but Unit 2 is the real headache.
 
  • #9,870
clancy688 said:
The contamination outside the plant is nearly entirely the fault of Unit 2.


Not as long as the Pacific Ocean lies outside of the plant.
You do realize that this is just a fluke result of wind direction don't you?
 

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