Japan Earthquake: nuclear plants

Jorge Stolfi

http://www.ic.unicamp.br/~stolfi/EXP...actor2-W-1.png
http://www.ic.unicamp.br/~stolfi/EXP...actor4-W-2.png

Those are from the great Air Photo Service set. Bot are views from East looking West. The East blow-out panel in #4 is the fourth from left, second from top. Note the clean edges.

PietKuip

I have made a graph of the I-131/Cs-137 ratio in Tepco's press releases here.

The yellow points are measurements in air. The trend of the ratio is consistent with the 8-day halflife of I-131.

The concentrations in water have a much larger spread. I will see if I can make sense of it. There is also the problem of the reliability of the numbers. There are many minor errors (in dates, for example). Sometimes there is clearly an error in the exponent. I made an emendation on April 7, where the concentrations of the particulate cesium isotopes were obviously wrong. Such errors are then reproduced in every graph that Tepco publishes, for example in http://www.tepco.co.jp/en/press/corp...s/110413e9.pdf

There are more places where I suspect copying errors. And maybe I made a copying error myself somewhere. But why is not Tepco publishing such graphs?? Are not they analyzing their own data themselves?

|Fred

This is what I understood from what you mentioned a few weeks back. But, (and this is pdObq question) to your knowledge
Was the design of the UNIT 1 meant to be weak permissive for explosion on this floor to be less damaging to the containment bellow ?

MadderDoc

I assume you restrict to those two options because you've seen a big cloud rising vertically, so you are looking for something that could serve as a vertical 'barrel' to produce this dramatic effect.

However, the vectoring of such a cloud needs no barrel. The cloud is mainly steam, hot steam, it forms a mass that is much lighter than atmospheric air. Once released, hot steam rises vertically 'all by itself', as a piece of styrofoam does when it is released under water.

PietKuip

Brilliant idea! I am very curious.

elektrownik

yes unit 1 is different, 2,3,4 have one blow panel on the turbine building side, you can see it for unit 2, also there was some ir image posted here where those blow panels were visible. Unit 1 reactor hall wall and roof is the same like 2,3,4 roof, steel construction with concrede without steel in concrede, 2,3,4 construction is concrede with steel rods inside (http://en.wikipedia.org/wiki/Reinforced_concrete)

Ms Music

I did search at least a month ago, and was unable to find anything above 4.0. I was unable to find a website that shows earthquake data smaller than 4.0 that was in English.

Best of luck!

MadderDoc

I am posting a few frames from a Daiichi video that was linked here recently. They show a pressure vessel cap during mounting, and the lifting in place of the containment cap.

I think these photos indicate what that big tetrapod thing is that rests on the top of unit 3 to the north of the crane. The tetrapod would seem to be a tool affixed to the crane when it is lifting the containment cap (and perhaps when it is lifting the pressure vessel cap too, the cap appears to have on top 4 handles that would fit).

Attached Thumbnails

 

triumph61

I compare the radiation map (tepco) with the yellow things witch are around unit 3.
The Radiation is at the same Place high where yellow pices are found.
the highest place 330 is the smal building.

unlurk

Correct, and the column of "steam" reached a height of 500 meters or so very quickly in a strong SE breeze.

I have seen a lot of steam releases in my time, but never one with that much energy.

TCups

Ever seen a volcano erupt?

unlurk

Possibly I'm being misunderstood.

I am not saying there was a nuclear explosion in the sfp.

On the basis of all the known information, I believe there was a criticality which occurred in the fuel pond.

The heat generated by the criticality created the steam explosion visible in the videos of the explosion of number 3.

The (sideways) hydrogen explosion was a powerful blast, but it was a mere puff when compared to the steam explosion which followed.

Please note that the vertical column of "steam" seen in the #3 blast was brown because it contained debris from the hydrogen blast and contents of the sfp.

This theory also appears to be supported by the presence of very "hot" radioactive debris around the site and the detection of neutron activity outside the site boundary.

Units 3 and 4 are the only suspects as the source of all the radiation around the site as far as I know.

And #4 may not have contributed much to the foul environment around the plant.

Jorge Stolfi

Could that much steam be generated from H2 + O2 ? The interior space of floors 3-4-5 is somewhat less than 30,000 m^3. Wikipedia says that explosion can happen with H2 concentration from 4% to 74%. If we take 40% (max that will burn anyway), that would be at most 12,000 m^3 of H2, which after the explosion would would become 12,000 m^3 of hot steam, which at atmospheric pressure would expand adiabatically to ... huh ... (end of my physics).

Anyway, 12,000 m^3 of H2 at 1 bar ~ 1000 kg of H2 <--> 9000 kg of H2O So the maximum H2 explosion assumed above would generate a mushroom comparable to that of the explosion of a boiler with 9 m^3 of liquid water, overheated to some temperature TBD. Is that compatible with your experience?

However for this maximum scenario we need 9 tons of water combining with zirconium (in the core, in the SFP, or both) to produce that 1 ton of H2. Is this reasonable?

If we take the lower figures, we get perhaps 20,000 m^3 of space filled with 4% H2. That means less than 70 kg of H2 <--> 630 liters of liquid water. That seems more reasonable as far as H2 generation goes; but would it yield enough steam for the mushroom we saw?

If we cannot match the amount of H2 likely to have been produced with the size of the mushroom cloud, two other possibilities are an explosive rupture of the RPV (several tons of superheated water there), or a criticality in the SFP (vaporizing some of the water).

TCups

@Unlurk:
Understand. Ultimately, it can be debated as to the precise source of heat that drove the steam explosion -- sudden criticality or otherwise, but not that a steam explosion occurred, IMO. The fundamental difference between the explosion at Unit 3 and the others was the component of the steam explosion, whatever its exact precipitating cause.

Basically, the water in the SFP would have been heated to the boiling point without a sudden criticality. And a hydrogen explosion would have added additional heat and, perhaps more importantly, sudden agitation of the heated water. It is plausible that a steam explosion may have occurred without or with sudden criticality. Based on the evidence and opinions of others here on the PF (Astronuc principal among them) I don't think sudden criticality occurred in SFP3.

BTW, I was pleased to see yet another new member also become a contributor to the PF. I did so, too, and believe the value received was well worth the contribution. Others are also encouraged to consider becoming contributing members. Thanks.

robinson

The explosion of Building 3 is fascinating. I would bet if there was video of the Building 4 explosion, it would be far more interesting as well.

jlduh

As general information about currently discussed safety policies evolutions in case of nuke accidents, i post this translation of a french article from 5th of May. Today have been hold auditions at the french parliament to discuss how to adress in the future, and after Fukushima, "unthinkable scenarios of accidents". "Thinking the unthinkable" is the main goal of a kind of task force that has been put in place after Fukushima where a succession of events ended up in a scenario that was never foreseen by plant designers nor self defense forces who had to cope with the desaster. They ARE NOW CLEARLY RECOGNIZING THAT CRISIS AND RISKS SCENARIOS ARE OFTEN TOO SIMPLISTIC AND DO NOT INCLUDE POSSIBLE DOMINOS EFFECTS (I mentioned this recently concerning the NRC SFP risk reassessment study, which never adressed the possibility that the reactor below the SFP could explode or trigger an explosion devastating the pools placed on the "attic"!).

Note they are also seriously considering the need to develop ressources able within 48 hours to be sent on site (with helicopters) with all the means necessary to provide an effective mobile backup of power AND water to deal with a total blackout situation in a NPP for all the reactors (loss of cold source and loss of power, from primary AND from onsite backup).

http://translate.google.fr/translate...aginable,23027

robinson

With out a back up cooling system nothing seems to be able to prevent a meltdown when something damages the heat exchange. Be it cooling towers, or intake/outflow from a river/ocean, if the cooling system fails, for what ever reason, there will be big trouble.

How to fix that?