Japan Earthquake: nuclear plants

artax

I must say I assumed some channelling of unit 3 explosion, or barrel if you like, due to the large piece that is propelled perfectly vertically, and falls almost where it rose from,... though probably slightly (though imperseptibly) to the right (or Southeast) due to the wind, the cloud however moves with the wind, due to it's low density.
That large piece must have been directly ballanced on the balloons centre if we're simply talking bouyancy! and what is it? the floor above the SFP?

SteveElbows

When you say orange light, do you mean the fireball to the south of the building thats clearly visible?

zapperzero

I circled it in the attachment. It's to the south I think, yes.

AntonL

or to cool the volume of the SFP by 1^oC would release .596 GJ

TCups

Understood. I was attempting to say that the total amount of heat required for phase change is a constant, but that it would not be correct to think that all of it must be applied instantly, or that very high temperatures are necessary to supply the heat of transition. Heat energy continues to be stored in water undergoing heating at 100ºC even though the temperature does not appear to change. There can be a huge difference in the total energy stored in two pools of water, each at 100ºC and each under the same pressure, unless I misunderstand the concept of the heat of transition and phase change.

Edit: Reference added - http://hyperphysics.phy-astr.gsu.edu...rmo/phase.html

True, but tiny droplets of water require less total thermal energy (although not per unit volume) than a massive pool of water requires in order to undergo the phase change. Is it not possible that atomized water droplets intermixed with burning hydrogen + oxygen might be efficiently heated and turned into additional steam during the hydrogen explosion itself?


In part, perhaps the hydrogen explosion itself, of course, but I strongly suspect a steam explosion based on what I see, even if I don't "know". I suppose that it is sort of like the old joke about the prostitute (do you know it?) . . . I presume that we have already established, by its characteristics that a large component of the explosion of Unit 3 was a steam explosion. So now, we are just haggling over the "price" (and source) of thermal energy required to fuel it. Anton gave some reasonable calculations, I believe.

Edit: Reference added - http://en.wikipedia.org/wiki/Water_vapor#Lifting_gas

Lifting gas
Due to its low molecular weight, water vapor is a lifting gas under STP conditions; however, it is limited by the low amount of water vapor which can exist in the air at a given point in time. High enough temperatures to maintain a theoretical "steam balloon" yield approximately 60% the lift of helium and twice that of hot air.[9]


Potential sources of thermal energy I can see are these:

1) thermal energy stored in the water of SFP3 transferred from decay heat of spent fuel rods in the pool,
2) thermal energy transferred from burning hydrogen in the building above SFP3,
3) thermal energy from the RPV transferred by explosive venting of steam and hot (radioactive) gasses from the drywell or upper "wet well" or both,
4) thermonuclear energy from sudden criticality occurring in the unspent fuel in SFP.

And say, don't I remember a passive emergency cooling system that operates without electric power driven by a steam turbine that circulates through a cooling pool? Was such a mechanism in operation at Unit 3? Would that have been in any way related to heating SFP3 (ie, was initial emergency cooling of the Unit 3 core at the expense of additional heating of SFP3 or is another water reservoir used for this emergency system, if it was used)?

Are there any other substantial sources of thermal energy that I have not considered?

I remember some earlier, detailed discussion about the calculation of energy released with the explosion of Unit 3 and, I believe that the final conclusion was that it could not even be estimated to within an order of magnitude with any reasonable accuracy. (sigh)

Edit by Borek: TCups, I corrected quote tags so that it is obvious what is a quote and what was your answer. If something is wrong, please contact me by PM and I will correct it again.

artax

this is one of the best shots without TV channel stuff covering bit up! could do with some contrasting though

http://www.youtube.com/watch?v=RxAHo...eature=related

jlduh

Concerning SFP's and plugs, did we already have a clear statement about this subject: are the SFPs normally plugged with concrete removable roofs (some kind of anti-missile protection i think?)?


At n°1 i don't see the SFP (maybe under the crane?), so is it plugged with these?

What about N°2 (which we don't see)?

N°3 we know that there is none currently, but what about before the explosion?

For N°4, even if it had some in normal use, it was getting fuel reloading so probably no plug anyway, which is consistent with what we see now.

Again, this subject is fuzzy to me. We can imagine that at N°3 for example, if there was some plug the explosion could be explained much differently.

I was really thinking that SFPs should have plugs for safety (missiles) reasons (which is a problem if cooling is stopped as gases are captured by the way!)

Could this explain the big hole above N°3 SFP, and maybe some big chunks of concrete thrown in the air?

zapperzero

Well, some nights the plant's all lit up and steam's coming out. Other nights it's pitch black.

elektrownik

No, there is no protection on SFP, they are open.

PietKuip

The newspaper article says about this bunker:
"The three-story, white bunker had extra-thick walls and two filtration systems designed to keep out radiation."
http://www.bloomberg.com/news/2011-0...fuel-rods.html

An earthquake-proof radiation shelter. Yet the radiation spike was measurable inside.
To me this is rather strong support for Gundersen's theory.

Rive

There was some really big pieces in that cloud, which cannot be explained by just lifting by heat.

Ps.: regarding that radiation spike in the safe bunker: is there even a direct view from the bunker to U3 service floor? To the depths of SFP?

|Fred

The SFP plugs as quoted in the service floor paper are the removable wall making a "channel" from the core to the SPF.

MadderDoc

Yes, pillar and mushroom development is not per se a signature of steam explosions. A good sized fireball (or steamball) and it is set to go.

A hot air balloon is usually operated at between 100 and 120^oC and will then produce a lift of about 3 N/m³. The lift of hot water vapour is about double of that, more than 6 N/m³. This is mainly because water has a much lower molar mass than atmospheric air. For comparison one of the best buoyancy gases we have, helium, has a lift of about 10 N/m³. IOW water vapour has over 60 % of the lifting capability of helium.

pdObq

Apparently they don't use the concrete shield plugs for the SFPs although those seems to exist (see posts a few pages back). (Still waiting for comments on this issue from those with first hand nuclear plant experience... just a reminder, not being impatient )

But what you write could have applied to the dryer-separator pool. Its shield plugs are much heavier than the SFP ones, and they might have put them in place just to have more floor space available. Maybe that could be related to the heavy floor damage in the NW corner of unit 3. Otoh, although we know there is steam venting from the side of the concrete blocks separating the DS pool from the reactor well, those blocks themselves seem undamaged.

EDIT: See post http://www.physicsforums.com/showpos...postcount=7054 which came up while writing this. That would make sense, as they are supposedly rather light. But do you know for sure, any documents where that's stated (might be in the whole document, I just looked at the two extracted pages so far)?

pdObq

But you don't want to imply that those large concrete chunks thrown upwards in the explosion are floating on some kind of hot gas?

AntonL

concrete chunks - I would say roof sheets judging by there size

whoswho69

Fukushima - One Step Forward and Four Steps Back as Each Unit Challenged by New Problems - Arnold Gundersen