Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Dmytry]

In reverse order:
We can see the 'shield plugs - cookies' off the containment in #3. One of the explosions can be just from the containment and not from the reactor. If, IF there still is reactor pressure that would strongly tend to indicate no explosion in the reactor. Just venting from under great pressure.

My sense as a fire fighter is that there is far more energy released in the Reactor 3 building than from #1. #3 took out all walls and roof.
Now this could be just a component of the size of the buildings or different construction methods later on.
Or it could be different explosive materials ...

Well, in special effects, the #1 would of required a dynamite stick, movies wouldn't even do that, too dangerous. #3, a very small charge inside condom with fuel. In CG, special effects, the first, you just instantly make a lot of air hot, it expands and cools, big cloud, doesn't rise. The second, you vent in giant amount of steam, or approximation thereof (magical air that does not cool down) and you get beautiful mushroom cloud. You can also color some of it burning. But no actual chemical explosion, just a burn. Movies barely ever do explosions like #1 . We really brainwashed everyone about explosions, haha. An explosion in movie is not even an explosion very much, just big fireball. It's also easier to do in CG.

 

[Atomfritz]

My sense as a fire fighter is that there is far more energy released in the Reactor 3 building than from #1. #3 took out all walls and roof.
Now this could be just a component of the size of the buildings or different construction methods later on.
Or it could be different explosive materials or the amount of in a larger space ...

it's because of different material.
Unit 1 has been built without reinforced concrete in the top part, as you can verify in the pictures.
So far less energy got absorbed by the walls, they just popped out and pulverized, leaving the steel girderwork almost undamaged.

 

[Dmytry]

it's because of different material.
Unit 1 has been built without reinforced concrete in the top part, as you can verify in the pictures.
So far less energy got absorbed by the walls, they just popped out and pulverized, leaving the steel girderwork almost undamaged.

look at the videos again, really. The #3 explosion was reported as much more loud from the distance. The #3 explosion had immense volume of air rising at very high velocity. Try explain that with the building material differences.

 

[MadderDoc]

I've stuck together the pieces of the roof structure of unit 3, by locating the single parts, then putting images of those in a 6 by 4 matrix, in the positions they were in before the hydrogen, and the following steam explosion. The result of my effort is this:

There's an html version of the same thing with the images in the original resolution, at
http://www.gyldengrisgaard.dk/fuku_docs/roof3.html

 

[PietKuip]

We can see the 'shield plugs - cookies' off the containment in #3. One of the explosions can be just from the containment and not from the reactor. If, IF there still is reactor pressure that would strongly tend to indicate no explosion in the reactor. Just venting from under great pressure.

In http://www.flickr.com/photos/26255918@N08/sets/72157626384577079/detail/ , I collected some of the thermal images of Unit 3 that the Japanese military has been publishing.

The Spent Fuel Pool is consistently at around 60 C. That would be a minimum temperature. If the temperature of the water is higher, there will be condensed steam obstructing the view of the water surface.

There are variations in the temperature of the containment, but that is due to different degrees of blurring. The chopper takes these images from 3000 ft high. The view of the containment is just a few pixels. There will also be cooler debris in the way.

 

[Bob S]

Energy and pressure in stoichiometric hydrogen-air mixture explosion

Heat of reaction - 3.3 x 10⁶ joules per cubic meter
Pressure - 8.15 bar (abs)
laminar flame speed - 28 m/s

For an empty building 50 m on a side x 50 m high

Total energy = 4 x 10¹¹ joules ≡ 95 tonnes of TNT (4.18 MJ per kg)

See http://www.gexcon.com/handbook/GEXHBchap4.htm

Bob S

 

[TedNugget]

Well, in special effects, the #1 would of required a dynamite stick, movies wouldn't even do that, too dangerous. #3, a very small charge inside condom with fuel. In CG, special effects, the first, you just instantly make a lot of air hot, it expands and cools, big cloud, doesn't rise. The second, you vent in giant amount of steam, or approximation thereof (magical air that does not cool down) and you get beautiful mushroom cloud. You can also color some of it burning. But no actual chemical explosion, just a burn. Movies barely ever do explosions like #1 . We really brainwashed everyone about explosions, haha. An explosion in movie is not even an explosion very much, just big fireball. It's also easier to do in CG.

Another way to tell the power of an explosion is how much was damaged and how far things where thrown.
Its not just that the #1 Reactor didn't have the power to disassemble and discard the roof, its that it didn't have the power to throw much around. Additionally, IMO, much of that darker portion of the #3 plume is from pulverized concrete. Generally with construction methods over time more rebar is the trend. That #3 has all of its concrete walls and ceiling trashed speaks well of that power.

 

[cphoenix]

1mSv/sec is 86 Sv/day. 10 Sv/day is considered absolutely lethal.

You are missing my point. I did not say 1 mSv/sec for 1 day. That would be lethal. But 1 mSv/sec for 1 sec would not be lethal. It would add up to a grand total of 1 mSv.

Likewise, a dose rate that would be dangerous if it lasted for a year might be non-dangerous if it lasted for only a month.

I was responding to a post that calculated backward from the 50 mSv/yr, to compute an acceptable hourly dose rate, and say that people should be told to evacuate rather than be exposed to that dose rate. The poster claimed that Fukushima City residents were at risk. This is a groundless calculation and an incorrect conclusion.

A dose rate that would give you 50 mSv in a year, if it continued at that rate for a year, would be acceptable for one week if it stopped after the one week.

I hope this is clear.

 

[Dmytry]

A dose rate that would give you 50 mSv in a year, if it continued at that rate for a year, would be acceptable for one week if it stopped after the one week.

if you don't ingest or inhale anything radioactive, then yes it would be stopped.
Really, there's 2 entirely different doses. The doses of radiation, which aren't really 'doses' in the chemical sense but just whole body averaging based on linear response model (and weighting factors for different tissues), and a dose of particular radioactive isotope of a particular element, that was inhaled/ingested/whatever and is retained. Fission products tend to be rare in Earth crust, and biologically many of them replace something like e.g. caesium replaces potassium and strontium replaces calcium, and then remain there for a while (in case of strontium, for rest of the life).

 

[Jorge Stolfi]

I've updated my plots of #Fukushima reactor variables to NISA release 97 (16/apr 15:00) :
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/Main.html

I have also added plots of core pressure (PC) against drywell pressure (PD), and of suppression torus pressure (PS) agains PD. They allow many interesting inferences to be made, although I cannot quite figure out a single one of them. Perhaps, if the data is not complete garbage, they will allow us to tell the water level in the drywell and/or torus, and/or the size of the vents/leaks between the three compartments, at each epoch since data started to be available.

 

[Dmytry]

Another way to tell the power of an explosion is how much was damaged and how far things where thrown.
Its not just that the #1 Reactor didn't have the power to disassemble and discard the roof, its that it didn't have the power to throw much around. Additionally, IMO, much of that darker portion of the #3 plume is from pulverized concrete. Generally with construction methods over time more rebar is the trend. That #3 has all of its concrete walls and ceiling trashed speaks well of that power.

Yep. And it being slow, it had to be *really* powerful.
Later on I'm going to see if i can find the approximate temperature of rising cloud from it's velocity and size. Assuming it's just rising by buoyancy. I'm very sure that #3 was not a premixed hydrogen+air explosion, but a hot steam+hydrogen venting (explosive venting if you wish), which ignited immediately, and the venting was powerful and fast enough to tear apart entire building, but nowhere near as fast as to create shockwave (confirmed both by lack of visible shockwave which was present in #1 and lack of dust raising by shockwave which was also present in #1).
The image analysis by MadderDoc indicates there was a jet of flame, damaging the steel with intense heat, rather than explosion.

 

[Jorge Stolfi]

I have also added plots of core pressure (PC) against drywell pressure (PD)...

I forgot to explain the color coding of these new plots. The numbers in the plot key are hours since mar/11 00:00. Thus 240-288 would mean a period of 48 hours between mar/21 00:00 and mar/22 24:00. I will try to make that clearer in future releases.

 

[Caniche]

Informative stuff folks ,many thanks .
So as a general overview would it be fair to say we are faced with a scenario of four nuclear reactors undergoing various stages of uncontrolled radioactive emissions that could possibly escalate to runaway critical reactions at any point within the next 10-30 years. RPV's breached;primary containment breached; sfp's look compromised and all you can do is pour on water to dampen the airborne effect but the effluent will just get pumped into the sea.
Any clues on Daini? all in cold shutdown but I notice that due to the cooling interruption the number of reactors at Three mile Island disaster level has jumped from two ,to three today.

 

[cphoenix]

A staggering amount of energy might be stored in pressurized water in spent fuel pools...

(Unless I've made a stupid arithmetic mistake. Someone please check my numbers and arithmetic - is this even plausible?)

Water at the bottom of a pool (40 ft?) is under about 2.2 atm of pressure, so would boil at about 125 C.

The heat capacity of water is 4 J / g C. So 25 C is 100 J/g. I'm assuming this is proportional to depth, so divide by 2 to compute the energy stored in a pool...

Google says that a spent fuel pool has about 1E4 tons of water. That's 1E4 Mg (1E10 g). So if the pool were poorly stirred and heated just right (so it was just below boiling at all depths), then it might have 5E11 J.

That's about 1/10 of a kiloton.

If a pool were in that condition, and then were shaken, the water might flash into steam very quickly. At 2260 J/g, 5E11 J could vaporize about 200 Mg (tons) of water. At ~600 g/m^3 density for steam at 1 bar, that would be about 300,000 cubic meters, or a 70-meter cube.

I'm sure the whole pool was not in this condition. But you could take away a couple of orders of magnitude and still have a very nasty explosion.

 

[Dmytry]

hmm mmm but won't hot water rise up to surface? convection stirring. I don't know how well the rods would prevent convection, especially that they have re-racked it for higher capacity...
edit: entirely unrelated question. Can you superheat egg in microwave oven, if the egg is contaminated with alpha particle emitting isotope? I think, not by much. Someone should do an experiment.

 

[clif]

I have a question;

Is the item seen in the photo of #4, second level down, fourth row from left, the top of the reactor vessel?

I know the caps have been removed, so this would be the top of the reactor vessel itself?

An aerial view of the Fukushima Daiichi Nuclear Power Station taken by the Air Photo Service, March 24, 2011.

If that is correct, would the location the steam under the roof lattice is rising from on March 14 after the explosion of #3 be the location of the reactor vessel ?

An aerial view taken from a helicopter shows damage sustained to the No. 3 reactor at the Fukushima Daiichi nuclear power complex, March 16, 2011.

I know the brighter steam cloud to the right in the pic is from the SFP in #3

I know they are different buildings, but same basic design, so the location of the reactor vessel would be the same.

The satellite view from March 14 shows two separate distinct steam clouds rising from #3;

The No.3 nuclear reactor of the Fukushima Daiichi nuclear plant is seen burning after a blast, March 14, 2011.

All images from here;

http://www.reuters.com/news/pictures/slideshow?articleId=USRTR2KAAL#a=26"

 

[cphoenix]

hmm mmm but won't hot water rise up to surface? convection stirring. I don't know how well the rods would prevent convection, especially that they have re-racked it for higher capacity...

Good question... now add an earthquake that might knock a flat sheet of material into the pool, on top of the cooling racks. That might cut down on convection quite a lot.

Suppose a single 1x2 m sheet of material, keeping the water stagnant in about 4 vertical meters of pool, near the bottom. That's 8 m^3 of water at about 22 C over boiling. That's about 700 MJ or about 0.17 ton of TNT.

If you want to try this at home, get a small drinking glass. Put in a few cm of water and a few cm of cooking oil. Heat it in the microwave. Nothing happens until BURP and you're cleaning oil off the roof of the microwave and there's not much liquid left in the glass. (Warning - this might blow the door open, scald you, and/or damage the microwave.)

The energy stored scales as the 4th power of the dimension. A few cm vs. a few meters implies a million times the energy of the microwave demonstration.

Chris

 

[Rive]

Indeed , they have much better helicopter footage , like :



or

Both footage are with recorders, and the first one has all the fingerprints of some postprocess techs (try VirtualDub and Deshake filter on the second footage if you want to see something similar).

What we have from the drones are the low bandwidth radio transmits (provided for the remote operator). IMHO.

 

[|Fred]

does anyone has a link to the video footage ,source of this picture?
http://www.reuters.com/resources/r/...04-15T130609Z_15_GM1E74F1KHK01_RTRRPP_0_JAPAN

 

[Rive]

What we have from the drones are the low bandwidth radio transmits (provided for the remote operator). IMHO.

 

[MadderDoc]

does anyone has a link to the video footage ,source of this picture?
http://www.reuters.com/resources/r/...04-15T130609Z_15_GM1E74F1KHK01_RTRRPP_0_JAPAN

http://www.tepco.co.jp/en/news/110311/index-e.html

Edit, sorry no, it is not there. Tepco's caption says 'A picture taken from the concrete pumping vehicle, the spent fuel pool, Unit3'.

 

[MadderDoc]

Ah, so there is the carrying bridge of the unit 3 FHM. As a tooth-picker stuck in a hollow tooth.

 

[jmelson]

Yep. I'm very surprised though that there was no word from explosion experts about the video. No estimates of energy, in traditional TNT equivalent.
I'm still looking for chimney height as quoted from official source. It seems clear to me that the explosion in #3 could not possibly have been a hydrogen explosion

I'm with you on this, Dmytry, I have always thought the energy in that explosion was way too much for hydrogen.

I swear I read somewhere on this forum that the vent towers were 130 or 135 m tall.

Jon

 

[jmelson]

edit: also, acetylene and other hydrocarbons leave soot.

Oh, YEAH, an acetylene fire or explosion would probably create an absolutely immense ball of soot and smoke, to judge what you get when you start up a torch before you get the Oxygen set right.

Jon

 

[Giordano]

http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/04/17/1304193_0416.pdf

New nuclide analysis of sea water. Record high levels of I-131 and Cs-137 30 km from Daiichi.

 

[jmelson]

I noticed that right away. Not only lack of the blast, but also dirt flying sideways quick in #1
And all around #3 looking much slower.
To me it looks like a best example of difference between hydrogen+air explosion vs venting of huge volume of hydrogen and steam. I did CG fluid work, its actually sort of my area of expertise. Reactor stuff, they report pressure not to be zero, i dunno, maybe the lid can be lifted off and then come back down, or maybe gauges failed.

Yup, with #1 the shock wave is clearly visible (much better on network video than mpg conversions), and would make more sense with a hydrogen explosion vs. a steam explosion at #3.

And, #1 was more clearly a horizontal blast vs. a vertical one at #3.

Jon

 

[jmelson]

And pict32 is a very interesting photo of FHM 4. The FHM has been "de-masted". Perhaps pretty strong evidence something violent happened within the confines of the SFP?

Yes, either something happened in the pool, or the FHM was moved suddenly and the mast broke off. I think that is pretty certain. It is conceivable if the FHM gantry doesn't have power-off brakes that the earthquake could have gotten it moving enough to cause the mast to hit a wall of the pool or other obstruction. But, something busted that mast off pretty sharply, and it probably is not all that fragile a component.

Jon

 

[bytepirate]

A staggering amount of energy might be stored in pressurized water in spent fuel pools...

(Unless I've made a stupid arithmetic mistake. Someone please check my numbers and arithmetic - is this even plausible?)

Water at the bottom of a pool (40 ft?) is under about 2.2 atm of pressure, so would boil at about 125 C.

The heat capacity of water is 4 J / g C. So 25 C is 100 J/g. I'm assuming this is proportional to depth, so divide by 2 to compute the energy stored in a pool...

Google says that a spent fuel pool has about 1E4 tons of water. That's 1E4 Mg (1E10 g). So if the pool were poorly stirred and heated just right (so it was just below boiling at all depths), then it might have 5E11 J.

That's about 1/10 of a kiloton.

If a pool were in that condition, and then were shaken, the water might flash into steam very quickly. At 2260 J/g, 5E11 J could vaporize about 200 Mg (tons) of water. At ~600 g/m^3 density for steam at 1 bar, that would be about 300,000 cubic meters, or a 70-meter cube.

I'm sure the whole pool was not in this condition. But you could take away a couple of orders of magnitude and still have a very nasty explosion.

but where is the triggering quake?
http://neic.usgs.gov/cgi-bin/epic/e...AT=0.0&CLON=0.0&CRAD=0.0&SUBMIT=Submit+Search

unit 3 explosion: 14th at 02:01 am (UTC)
unit 4 explosion: 14th at 21:00 pm (UTC)

 

[jmelson]

Well, in special effects, the #1 would of required a dynamite stick, movies wouldn't even do that, too dangerous. #3, a very small charge inside condom with fuel.

One stick of dynamite would barely break windows in those large buildings. And, #3 was a lot more energy than that.

Jon

 

[MadderDoc]

Oh, YEAH, an acetylene fire or explosion would probably create an absolutely immense ball of soot and smoke, to judge what you get when you start up a torch before you get the Oxygen set right.

Jon

Curiously, there appears to be black smoke and soot evolving at the seaside of unit 4 on one of the most recent Tepco handouts. Right in the middle of the photo. But of course it doesn't necessarily have to be acetylen burning.
[URL]http://www.tepco.co.jp/en/news/110311/images/110415_1f_3_7.jpg[/URL]

 

[HowlerMonkey]

If any acetlyene went up, it is safe to assume that the oxidizer sitting in the bottle next to it went up as well...most likely first because of the much higher working pressure of the tank making it subject to exploding from overpressure due to heat.

The oxygen cylinder is 2200psi and the acetlyene cylinder is 250psi.

A hot interior of a van has been known to cause an oxygen cylinder to overpressure and rupture.

It is more likely that heat caused an oxygen bottle to rupture which in turn released sharpnel that would ventilate the acetelyene bottle.

Due to the fact that there is a much larger percentage of oxidizer (also...pure oxygen rather than air) than stoich, there would be very little, if any soot because the combustion would be complete.

Another phenomenon is that most anything will burn with extreme vigor when in a very high concentration of oxygen environment...verging on an explosion.

 

[jmelson]

If any acetlyene went up, it is safe to assume that the oxidizer sitting in the bottle next to it went up as well...most likely first because of the much higher working pressure of the tank making it subject to exploding from overpressure due to heat.

The oxygen cylinder is 2200psi and the acetlyene cylinder is 250psi.

A hot interior of a van has been known to cause an oxygen cylinder to overpressure and rupture.

It is more likely that heat caused an oxygen bottle to rupture which in turn released sharpnel that would ventilate the acetelyene bottle.

Due to the fact that there is a much larger percentage of oxidizer (also...pure oxygen rather than air) than stoich, there would be very little, if any soot because the combustion would be complete.

Another phenomenon is that most anything will burn with extreme vigor when in a very high concentration of oxygen environment...verging on an explosion.

OK, then a stoichiometric or oxygen-rich acetylene fire will release an absolutely IMMENSE white flash, I mean almost nuclear detonation-class flash that would be seen for miles.

But, an acetylene cylinder that is punctured will not generally release acetylene very quickly, it takes a while to fizz out of the acetone/filler mix. The tanks are filled with a clay-like filler, and then saturated with acetone, then the acetylene is dissolved in that sort of like CO2 in soda.

Jon

 

[shogun338]

Curiously, there appears to be black smoke and soot evolving at the seaside of unit 4 on one of the most recent Tepco handouts. Right in the middle of the photo. But of course it doesn't necessarily have to be acetylen burning.
[URL]http://www.tepco.co.jp/en/news/110311/images/110415_1f_3_7.jpg

[/URL]
I think its just a shadow of the pipe on the right . T - Hawk video of Unit 4 , 4-15-11

 

[etudiant]

Best footage yet, from the T Hawk drone:

http://ex-skf.blogspot.com/2011/04/fukushima-i-nuke-plant-latest-photos-by.html

An expert analysis of these shots should tell a lot about the specific damage at each reactor .

 

[shogun338]

New T-Hawk video from 4-15-11 . Some closer shots of Unit 1 and Unit 3 . Video quality looks a little better .