Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MiceAndMen]

There is nothing complicated about the explosion of #4 - except where did the hydrogen come from - and that seems to be answered by the radiolysis explanation.

There is now some question whether the #4 explosion involved hydrogen at all, in which case the radiolysis explanation is incorrect. Start spinning.

 

[unlurk]

There is now some question whether the #4 explosion involved hydrogen at all, in which case the radiolysis explanation is incorrect. Start spinning.

There have been some actual physicists in this thread who have proposed a theory that radiolysis could have provided an ample source for the amount of hydrogen needed for an explosion of that size.

With no electricity there could have been no air circulation in building four and the trickle of radiolysis would have just kept accumulating.

That makes sense to me, because the damage to the unit certainly seems consistent with a hydrogen explosion, undamaged fuel pond and all.


Maybe Astronuc should E-mail some of his friends if Tepco really is going out in left field on this one. The physics forum may be ahead of them on unit four.

 

[|Fred]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

THANK YOU

I hope this will be enough for the disbeliever get over the tilting UNIT 4 theory

http://farm4.static.flickr.com/3056/5705932388_dca31f4961_o.jpg
http://farm3.static.flickr.com/2369/5705368411_4a2ee8f0a6_o.jpg
http://farm4.static.flickr.com/3099/5705937752_99f42dca4b_o.jpg

There is some other interesting pictures for ex: it is surprising to see that the cast transfer truck entry show some 'from the inside' blast damage on unit 4 while not on unit 3

 

[AntonL]

TEPCO rethinking the hydrogen-explosion hypothesis for Unit 4:

http://www.yomiuri.co.jp/feature/20110316-866921/news/20110509-OYT1T01116.htm

Lack of damage seen in SFP4 videos, along with low water contamination measurements, suggests that the explosion at Unit 4 may not have been due to hydrogen after all. TEPCO is pondering other possibilities, including 100 tons of pump-lubricating oil that are stored in the building, as well as propane tanks that were there for welding.

There is now some question whether the #4 explosion involved hydrogen at all, in which case the radiolysis explanation is incorrect. Start spinning.

IMHO, Yomiuri Press cannot be taken too seriously. The "Gate Theory" saved by the flood only they reported and I bet that the "Lube & Propane Theory" will remain a Yomiuri exclusive.

However, should it be true then it is really a sad state of affairs that a nuclear power plant can be destroyed by maintenance material. How will nuclear power plants be maintained in the future?

Are the lube barrels that hold potential flammable material nuclear certified? I bet not, just a standard 44 gallon drum.

Are the propane (or is it acetylene that is normally used for welding) and oxygen tanks or cylinders nuclear certified so they can be used in a nuclear power station.

 

[GJBRKS]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

These photos were taken by a person concerned in late April.

http://www.flickr.com/photos/xtcbz/5705937752/in/set-72157626687253144/

looking at these pictures I'm amazed at how lucky they were that no one was seriously hurt during the unit #3 explosion.
The force just blew the walls out of the back of adjacent buildings.
The scale of it is enormous ,something that I sometimes miss because of all these birdeye views

 

[sp2]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

These photos were taken by a person concerned in late April.

Forgive me if this is old news that I somehow missed, but these pix are pretty incredible.

The first thing that jumps out at me is that a lot of the upper superstructure of R3 and R4 has vanished since the last time I saw new close-ups.
I've seen some indications to that effect in the last few days, but I assumed they were nonsense.

These pix clearly show that a whole lot of structure is gone. (I'd have to dig up some older pix, for comparison, to be sure, but I really don't think it's my imagination, is it?)

What the hell happened to it?

Did they cut a whole bunch of stuff down, or did it fall in an aftershock?

And, either way, why haven't we heard about it before?

(And wouldn't either event pose a gigantic risk? Like of one of those gigantic pillars plummeting into an SFP?)

Somebody help me out here.

 

[|Fred]

..

One article that is relatively unbiased
http://www.scientificamerican.com/article.cfm?id=mox-fuel-nuclear
And an other with some factuals informations
http://www.ans.org/misc/ans-technical-brief-mox-fukushima.pdf

and again while I have no doubt Areva has some interest in the process. But Fukushima is a textbook example of what happens to a GE MK-1 NPP Failure, the main concern should be for the dozen US NPP based on similar design. And so far the "our NPP are not exactly the same , this will never can happens over here" is to me far from convincing.
So you can focus on the 6% mox fuel used in UNIT 3. If you like I'll focus on the 4 Failing MK1 NPP

 

[jim hardy]

@TCups

i have been toying with similar idea, speculating orange flame came from inside containment and squeezed out from under yellow domed top at flange..
Cant prove it was nor can prove it wasn't.

A cloud of hot H2 & steam squeeezing out from under containment cap would go horizontal at first and there's a low place in the wall between reactor and fuel pool for refueling crane to maneuver that'd duct it one direction..

Is this picture credible or was somebody playing with photoshop? it as linked a few pages back.
http://img34.imageshack.us/img34/6077/aerial201133002011.jpg

criticality in pool i don't buy either. They use either boron bearing metal to build the racks or boraflex silicone plastic inserts between the fuel assemblies to assure plenty of shutdown margin. i couldn't figure a credible mechanism for removing the boron.

In the vessel criticality is a lot more likely imho. But pressure readings here, kindly linked by somebody above, infer the vessel held pressure a while after explosion. Any idea where those sensors are and what's their reliability? Pressure dropped from 3 atmospheres to 2 at time of explosion. Sorry for units I'm old and just don't do metric - atmospheres is Kpa/100... 101.3 if one wants to be picky.

and to the several who've asked, hydrazine is used in PWR's to scavenge oxygen out of the water - a trickle of it is injected into the water going in. Being mostly hydrogen it turns free oxygen back into water. I don't know if it's common practice for BWR's.

 

[Samy24]

Also heard on radio that they are going to try feeding water through a different line at Unit 3 later today, due to the rising temperatures there, since merely increasing the flow rate through the current one is not working, suggesting that the water is not getting where it needs to go for some reason.

Looks like they have manged it!
http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05100600.pdf

 

[Jorge Stolfi]

IMHO, Yomiuri Press cannot be taken too seriously. The "Gate Theory" saved by the flood only they reported and I bet that the "Lube & Propane Theory" will remain a Yomiuri exclusive.

There were three explosions at about the same time, all three similar in that the damage occurred mostly in the 5th floor. It is hard to believe that they were all caused by freak accidents with lubrication oil or welding supplies; or that #4 was due to an entirely different cause than #1 and #3.

Also, lubricating oil should not create an explosive mixture with air, unless it is heated to its boiling point, which presumably is >>100 C. What would have been the source of the heat? In #4 the reactor was empty so there was no superheated steam anywhere in the building, not even in the SFP it seems. And then oil vapor would presumably explode with an orange fireball and black sooty smoke. I see hardly any sign of that in the videos of the explosions of #1 and #3.

 

[elektrownik]

Looks like they have manged it!
http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05100600.pdf

no way, 6 hours and 170C difference ?? strange, or it was sensor error...

 

[razzz]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

These photos were taken by a person concerned in late April.

Thanks for those pics, couldn't get them originally. Saying the plant is a disaster area is an understatement. Turbine buildings blown outward, vehicles standing on end, etc.

Unit 4: Unless the exterior skin was built just to rigid, they didn't plan on that type of explosion that occurred thereby undermining the structural support for the SFP. Before the noted explosion there were reports of fires and then the fires burning out but no visual or conformation of the fires or their location at the time. Some educated guesses posted here on possibilities of some other source(s) exploding at Unit 4 were assembles in transit/diesel/lubricants/acetylene bottles or whatever else might have been onsite for the shroud remodel. One of them might be a winner. You might throw in the backup batteries just to sure and not forgetting avenues of travel available from the other Units.

Unit 3, I'm guessing, vaporized nuclear fuels and sent them airborne around the world. I doubt the pellets even survived the heat.

Unit 2 seems to have blown some lower plumbing enabling radioactive lava to flow freely once it cleared the RPV since spreading allows borated water to intermingle on more surface area, no big booms just lots of radioactivity.

Unit 1 seems to have functioned well in this dilemma, too bad though since remaining fuel rods and the melted mix are still contained in the RPV making it harder to cool a ponding of the melt that continues to heat the remaining assemblies above.

 

[Jorge Stolfi]

A cloud of hot H2 & steam squeeezing out from under containment cap would go horizontal at first and there's a low place in the wall between reactor and fuel pool for refueling crane to maneuver that'd duct it one direction..

Is this picture credible or was somebody playing with photoshop? it as linked a few pages back.
http://img34.imageshack.us/img34/6077/aerial201133002011.jpg

criticality in pool i don't buy either. They use either boron bearing metal to build the racks or boraflex silicone plastic inserts between the fuel assemblies to assure plenty of shutdown margin. i couldn't figure a credible mechanism for removing the boron.

Aluminum melts at ~650C; from the description of boral, it seems to be mostly Al, so it should flow down at that temperature. Now, the reaction Zr+H2O is said to begin at 800C or higher. Thus getting rid of the boral seems to be easier than generating the required amount of H2. Or was radiolysis enough?

 

[Samy24]

no way, 6 hours and 170C difference ?? strange, or it was sensor error...

Not all readings are down that much. But you are correct the mass is >100t and there sould be a delay in the temperature change.

Maybe at the measurement point with the biggest drop there was no water before. After the change of the injection path there is now water at that place.

 

[BlueCactus]

TEPCO released a detailed layout of temperature meters for a press corps.

 

[Borek]

Actually, the thought was that a still pool of absolutely pure water might superheat, and that an explosion venting through the fuel transfer chute, particularly one that caused a very violent agitation (atomization?) of the pre-heated water as well as initiating an accompanying, secondary hydrogen explosion in the upper floor might well result in the phase change of a sufficient volume of water to steam to result in an "eruption" from the SFP.

That was cphoenix idea:

https://www.physicsforums.com/showpost.php?p=3255628&postcount=4280

I never liked the idea of superheating, as there is plenty of objects in the water that should easily help to start local boiling (see http://en.wikipedia.org/wiki/Boiling_chips - that's all about rough surface) and remove excess heat. This boiling will be very localized, not different in its effects to bubbles of carbon dioxide evolving as a line of beads in a glass of beer, you must have seen it. However, amount of energy stored in the pool water is impressive, and something occurred to me just now. After the hydrogen explosion there should be an implosion phase - lowering the pressure above water - and that could be enough to start flash boiling.

 

[dh87]

For the #4 explosion, the absence of fuel damage appears to exclude hydrogen generation from Zr oxidation. I am skeptical that radiolysis is sufficient for hydrogen generation for an explosion. Wikipedia says that radiolysis is mainly caused by alpha particles, in which case it's only a major issue if the fuel rods are damaged, I think. It's important to consider that this is a comparative rates argument. Hydrogen diffuses rapidly (Graham's Law), and it's hard to accumulate hydrogen over a long period. Perhaps someone who knows could provide a real radiolysis rate estimate that would refute what I'm arguing, but it appears that hydrogen isn't the cause of this explosion.

Can the #4 explosion be a steam explosion? There are two reported fires in #4. A fire could heat up a steel structure: a crane, a replacement shroud [I have no idea what one is or what it's made of], some steel girders. A hot steel structure could fall into water. There's the SFP, filled with water, the RPV is filled with water, and there's 5 meters of water in the basement of the building, although I don't know how accessible this is to falling things. Can heated steel falling into water make enough steam to blow up the building? I thought that this might be a good explanation, but I calculate that you'd need too much steel, although I might have made a mistake.

 

[MiceAndMen]

There have been some actual physicists in this thread who have proposed a theory that radiolysis could have provided an ample source for the amount of hydrogen needed for an explosion of that size.

Indeed they have, and it's something worth investigating further. And they may be right. The PDF file AntonL linked back on 7 May, "Light Water BWR Radiolysis", is compelling. I lean towards a hydrogen explosion myself in Unit 4 and agree the radiolysis theory could explain it.

Edit: Not worth arguing about.

What's lacking is a good CFD simulation in tandem with a FEA run that demonstrates that a 150 kg hydrogen detonation (or deflagration) can account for the physical results we see in the photographs of Unit 4 post-explosion. (Come to think of it, a similar study for Unit 3 would be most welcome.)

If you're really game, as you say, post that and we'll consider the matter settled. Lashing out at those whom you perceive as having some sort of agenda against you is unbecoming.

 

[elektrownik]

Not all readings are down that much. But you are correct the mass is >100t and there sould be a delay in the temperature change.

Maybe at the measurement point with the biggest drop there was no water before. After the change of the injection path there is now water at that place.

Also if cold water would hit 300C metal there should be much steam, but there wasnt on live webcam
Ubit 4: I want pictures of empty RPV first...

 

[jim hardy]

Aluminum melts at ~650C; from the description of boral, it seems to be mostly Al, so it should flow down at that temperature. Now, the reaction Zr+H2O is said to begin at 800C or higher. Thus getting rid of the boral seems to be easier than generating the required amount of H2. Or was radiolysis enough?

Well in order to melt either the Boral metal or the Boraflex plastic, the fuel would have to be not under water. Then it could melt, if the water were gone.

But without water it can't go critical. It'd have to get covered with water again to go critical and they weren't adding water to pools yet on day of explosion - it's reported to have started days later. They were still adding seawater to reactors.

so that's the catch-22 I'm in on pool criticality.

 

[|Fred]

I for my self do not see (so far) any change in the structure in the above picture , compared to the one taken a month ago. May be I'm not looking hard enough ?

 

[AntonL]

However, amount of energy stored in the pool water is impressive, and something occurred to me just now. After the hydrogen explosion there should be an implosion phase - lowering the pressure above water - and that could be enough to start flash boiling.

I like this idea , stated so in https://www.physicsforums.com/showpost.php?p=3199497&postcount=641"

 

[|Fred]

After the hydrogen explosion there should be an implosion phase - lowering the pressure above water - and that could be enough to start flash boiling.

I postulated that the video of unit 3 Blast showed an implosion after the initial "lateral explosion" and before the vertical component. This might not be to far fetched after all

 

[MiceAndMen]

IMHO, Yomiuri Press cannot be taken too seriously. The "Gate Theory" saved by the flood only they reported and I bet that the "Lube & Propane Theory" will remain a Yomiuri exclusive.

However, should it be true then it is really a sad state of affairs that a nuclear power plant can be destroyed by maintenance material. How will nuclear power plants be maintained in the future?

Are the lube barrels that hold potential flammable material nuclear certified? I bet not, just a standard 44 gallon drum.

Are the propane (or is it acetylene that is normally used for welding) and oxygen tanks or cylinders nuclear certified so they can be used in a nuclear power station.

Anton, I agree completely. I was just yanking unlurk's chain. I didn't post the Yomiuri story link; it just happened to pop up at a convenient time.

Propane doesn't seem likely. Acetylene on the other hand... I don't know. It depends on how much there was and where it was being used and stored. We're really getting to the point where we need some mass and energy estimates that might account for what the pictures show us, for both units 3 and 4. Such analyses could help to narrow down the different hypotheses floating around. Unfortunately I don't have the resources to do CFD in my spare time. I doubt anyone here does.

 

[razzz]

I for my self do not see (so far) any change in the structure in the above picture , compared to the one taken a month ago. May be I'm not looking hard enough ?

Yeah, just a different view from ground level instead of overhead. Unit 4 they don't dare breathe on, 2 & 3 are just to 'hot' to work on so only Unit 1 is approachable.

 

[MiceAndMen]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

These photos were taken by a person concerned in late April.

I wish to add my thanks for these pictures as well.

 

[Jorge Stolfi]

Forgive me if this is old news that I somehow missed, but these pix are pretty incredible.

The first thing that jumps out at me is that a lot of the upper superstructure of R3 and R4 has vanished since the last time I saw new close-ups.

Indeed, they sem to have been clearing away some of the rubble. For instance, the damaged stairwell enclosure on the service floor of #3 is gone.

The photos of #3 show a concrete-pump-like equipment that seems to be fitted for that task, rather than for water-pumping.

Removing the rubble makes a lot of sense for various reasons: safety of personel below, understanding what happened, clearing the way to the spent-fuel pools, securing loose radioactive material that could be washed down by rain or blown away by the wind, etc..

A few other things that struck me in those photos:

* The crane of #1 is in place at the south end of the service floor and held up the roof slab, although its rails have ceded by a few meters under the weight. Presumably the FHM is parked under it.

* In #3, the explosion pushed part of the south wall on the 4th floor, next to the SW corner,out by ~2 meters. (That explains why I could not fit my POV-ray models to that corner of the building!)

* Also in #3, the crosspiece at the western end of the crane got bent; so that the south longbeam of the crane is resting on the service floor, while the north longbeam sank into it, by a meter or so.

* Also in #3, northwest corner of the equipment pool's wall is missing and seems to have been blasted outwards, contributing to the mess on that corner. Among that is a big pece of equipment, tilted and half sunk into that pool. (The Missing FHM? the Mighty Spanner?)

* There are still lots of spaghetti-like grey rods among that mess at the NW corner of #3. (Rebar? Shouldn't it have rusted by now?)

* In #4, the explosion seems to have traveled down the stairwell at the SW corner, which had a concrete wall around it. There seems to be another stairwell at the NW corner (but withr longer stair sections, and without a concrete wall?), and the explosion apparently went down that way too. (Those two stairwells and the elevator well seem to be the only communication between the service room and the lower floors. The elevator well goes---apparently without any walls---all the way down to the ground floor, where it connects to the entrance "tunnel". Thus the damage to the latter is not entirely surprising. Presumably the truck parked at the tunnel's entrance diverted he blast wave against the walls, thus explaining why the damage is mostly near that end.)

* The artwork on #1's exterior walls is symetric about the NW corner.

 

[AntonL]

Hydrogen diffuses rapidly (Graham's Law), and it's hard to accumulate hydrogen over a long period. Perhaps someone who knows could provide a real radiolysis rate estimate that would refute what I'm arguing, but it appears that hydrogen isn't the cause of this explosion.

I am no expert but just applying knowledge documented by others.

Please see my https://www.physicsforums.com/showpost.php?p=3287847&postcount=6068" and then make your opinion.

Use the links in #6210 to download reference paper - it will be faster

 

[Rive]

http://www.flickr.com/photos/xtcbz/sets/72157626687253144/

These photos were taken by a person concerned in late April.

Many thanks.

This one: "[URL
[/URL] is a turbine building with a blowout panel removed?


Oooops! http://www.tepco.co.jp/en/news/110311/images/110510_1.zip"

 

[rowmag]

Anton, I agree completely. I was just yanking unlurk's chain. I didn't post the Yomiuri story link; it just happened to pop up at a convenient time.

Propane doesn't seem likely. Acetylene on the other hand... I don't know. It depends on how much there was and where it was being used and stored. We're really getting to the point where we need some mass and energy estimates that might account for what the pictures show us, for both units 3 and 4. Such analyses could help to narrow down the different hypotheses floating around. Unfortunately I don't have the resources to do CFD in my spare time. I doubt anyone here does.

One thing about propane is that it is heavier than air, and Unit 4 shows much more damage at the levels below the refueling floor than Units 1 and 3, so that would seem to be a point in favor of TEPCO's new theory. (And they seem to be saying they had propane tanks there, no mention of acetylene. Could the Mickey Mouse ears have been propane tanks stored around the back, with a feed through the wall to the welding area, with that feed line leaking as a result of a the earthquake, an aftershock, or the Unit 3 blast?)

 

[Jorge Stolfi]

Yeah, just a different view from ground level instead of overhead. Unit 4 they don't dare breathe on, 2 & 3 are just to 'hot' to work on so only Unit 1 is approachable.

At the southwest corner of unit #3, on the service floor, there used to be a bit of concrete wall, formerly enclosing the stairwell. It was damaged at the base and leaning to the west. Check this AP/Air Photo Service photo from early march:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/drone/hcrop/reactor3-Z-3.png

That bit of concrete seems gone now.

 

[Borek]

I like this idea , stated so in https://www.physicsforums.com/showpost.php?p=3199497&postcount=641"

So the credit goes to you :shy: That's not the first time (neither in this thread nor in my life) when I force open doors that someone else found a key to much earlier.

The energy had to come from somewhere else and I can't buy into the idea of it coming from the latent heat of the SFP.

See link below. The energy was there.

Tubs of hot water just don't have a reputation for blowing up like that.
This would be a first.

You don't need a tube, glass is enough to see what may happen. http://www.youtube.com/watch?v=1_OXM4mr_i0&feature=fvsr Or google for Old Faithful eruption.

However this runs counter to theory and practical experience with superheated water. Yes, you can make it hiccup, but you just cannot make it flash into large amounts of water vapor. Problem is, 2000 kJ/kg is needed to vaporize water, and it has to come from somewhere. If we assume generously, that the water in the sfp had managed to superheat to 10 deg C above bp , without its boiling, the water would have a surplus energy content of only about 40 kJ/kg. There would be energy to vaporize only 2% of it.

See cphoenix posts, he tried to estimate amount of energy in the heated water and they were really impressive https://www.physicsforums.com/showpost.php?p=3250188&postcount=3914 - and even if there were enough to vaporize "only" 2% that still means very large volume of steam. That would be on top of initial destruction done by the hydrogen detonation. So the hydrogen blows the walls/roof, then steam erupts, adds to the destruction and sends a mighty puff into the sky.

I postulated that the video of unit 3 Blast showed an implosion after the initial "lateral explosion" and before the vertical component. This might not be to far fetched after all

Yep, vertical component would be mainly water geyser after hydrogen kaboom.

The only thing that I still find doubtful is that it needs a substantial heat gradient between the top and the bottom of the pool, and the water should mix by convection. However, stored fuel must slow down the circulation, so could be the energy was there, just not as much as the original estimate shows.

 

[rowmag]

Oooops! http://www.tepco.co.jp/en/news/110311/images/110510_1.zip"

Yikes, that is not pretty.

 

[BlueCactus]

The Isotopes detected from sampling water of #3 Spent Fuel Pool.

Cs134 :1.4 * 10 ^11 [Bq/m3]
Cs136 :1.6 * 10^9
Cs137 : 1.5 * 10 ^11
I131 : 1.1 * 10^10

Location : Southwest side
Depth : 50cm below the water surface
Height : 6m above the fuel rod
volume: 40 cc

*precise value and underwater footage will soon be released.

 

[jlduh]

High levels of Strontium 89 and 90 found in soil around Daichi reactors:

http://www3.nhk.or.jp/daily/english/09_01.html



Note this also:


To the isotopes specialists: does these levels of strontium tells something about the cores destructions or possible criticalities? What are the most possible ways this strontium went there? By dust and particulates during the explosions? By steam?

Ok, in order to group in one post (this one) all the infos so far about STRONTIUM (which is an important subject i think), i add here (already posted):

-the Tepco measurement analysis of soil

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110508e7.pdf

- and seawater
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110508e5.pdf

the analysis of air showed no current traces of strontium (volatile or dust)
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110508e9.pdf

And also this article: Govt to monitor radioactive strontium levels

http://www3.nhk.or.jp/daily/english/09_28.html

Goshi Hosono made the remark to reporters on Monday, one day after Tokyo Electric Power Company detected high concentrations of strontium-90 in soil samples taken on April 18th inside the plant's compound. The amount is about 130 times higher than the maximum level observed within Fukushima Prefecture after past foreign atmospheric nuclear tests.

[...]

Noting the danger of strontium to human health, he said a detailed investigation is needed, including analysis of past data, to determine how the radioactive substance was scattered.

Once inhaled, radioactive strontium accumulates in bones, like calcium, and could cause cancer.

On April 13th, the science ministry announced that 3.3 to 32 becquerels per kilogram of strontium-90 was detected in soil samples from 3 locations in Namie Town and Iitate Village, 30-kilometers from the Fukushima plant. It also said an extremely small amount of strontium was found in plants taken from Motomiya city, Ono Town and Otama and Nishigo Villages, which are 40 to 80 kilometers from the Fukushima plant. The samples were taken on March 16th and 19th, 5 to 8 days after the accident at the plant.

 

[MadderDoc]

<..>
Is this picture credible or was somebody playing with photoshop? it as linked a few pages back.
http://img34.imageshack.us/img34/6077/aerial201133002011.jpg

Well, it is kind of naive. There's no good reason to believe that the reactor cap in unit 3 has a hue similar to a color fill of the reactor cap in a drawing of a bwr. Without the color clue, the picture has really nothing to indicate that it's the cap there in the equipment pool, it could be anything.

 

[razzz]

Anyone use .docstoc? Can you open this link for this document... http://www.docstoc.com/docs/7254461/Reactor-Pressure-Vessel-Issues-Printable-Version

 

[Concrn&Curius]

1. After seeing those photos of the site, all I can say is that the scale of the damage was just plain shocking.
2. I have a question about unit 3: Has anyone been watching wind directions since the accident? I know I have seen dispersions of the fallout that all indicate a NW trajectory. After seeing those photos, it looks like unit 3 was a cannon aimed in that direction. The Eastern walls are more intact, and the NW corner is just wrecked. That is where the flame "escaped?" as well. Would that all be consistent?

 

[razzz]

1. After seeing those photos of the site, all I can say is that the scale of the damage was just plain shocking.
2. I have a question about unit 3: Has anyone been watching wind directions since the accident? I know I have seen dispersions of the fallout that all indicate a NW trajectory. After seeing those photos, it looks like unit 3 was a cannon aimed in that direction. The Eastern walls are more intact, and the NW corner is just wrecked. That is where the flame "escaped?" as well. Would that all be consistent?

I read the wind direction carrying the explosion from Unit 1 caused most of the fallout/no-go zone since the cloud from Unit 3 explosion was carried by the winds directly offshore. Besides the ongoing uncontrolled releasing of contamination.

 

[AntonL]

Oooops! http://www.tepco.co.jp/en/news/110311/images/110510_1.zip"

What a mess, remote controlled submarines will be needed to clear the rubble to get to the spent fuel.

All I see are roof beam sections, rebar and concrete rubble, what is up or down is difficult to judge, bubbles seem to move horizontally at times,

look at the corrosion on whatever these are (right hand side)
[PLAIN]http://k.min.us/inkut8.JPG

 

[Jorge Stolfi]

Well in order to melt either the Boral metal or the Boraflex plastic, the fuel would have to be not under water. Then it could melt, if the water were gone. But without water it can't go critical.

By the time fuel became partly uncovered and the rods heated up to >700C, the space between the fuel rods would be filled with superheated steam. Also the space above the fuel, up to the top of the SFP, would be filled mostly with hot steam (except for some air flowing down by convection). Would that be enough water to allow for criticality?

The density would be much less than liquid water, but the volume would be much larger than inside a reactor's core. I presume that fast neutrons that escaped upwards or sideways would not be readily absorbed, and so would eventually be slowed down and scattered back to the fuel. Here I am thinking by analogy with light that falls onto a deep cloud deck: since it is scattered but not absorbed by the water droplets, it will all eventually scatter back out, exiting on the same side it entered --- no matter how rarefied the cloud dech is. (That is why large clouds look white on the sunlit side, and black on the other side). In the above scenario, H2 nuclei and neutrons would substitute for water droplets and photons.

 

[|Fred]

At the southwest corner of unit #3.

this is correct the frame is still there but the thin concrete seems gone? or may bi it is the white structure at the bottom of the picture (unlikely though)


New video on Tepco press downloads - this time it's about SFP#3!
=> at last .. we don't see much beside lots of roof structure fallen into the pool

 

[~kujala~]

Also, lubricating oil should not create an explosive mixture with air, unless it is heated to its boiling point, which presumably is >>100 C.

As fas as I have understood the current view of TEPCO is that at the unit 4 there was first an explosion and only afterwards fire. At least this is the impression I have got when reading TEPCO's/government's press releases.

I think one could achieve the best results by taking somehow seriously this new information coming from the press and trying to combine it with the theories presented here and try to see does it lead somewhere.

The general fire point of lubricating oil is probably somewhere betweeen 200 - 300 degrees celsius.

We could also think that this oil is in responsible for the fire but not for the explosion.

Is it possible that the explosion could have immediately heated a small part of the oil over fire point and also ignited it? The result of this would be a couple of fires here and there that would be extinguished by itself?

The explosion itself could be explained by AntonL's theory (radiolysis) or something else.

 

[MiceAndMen]

* The artwork on #1's exterior walls is symetric about the NW corner.

I'm fairly certain the artwork is symmetric on all the RBs with respect to the NW and SE corners.

Oooops! http://www.tepco.co.jp/en/news/110311/images/110510_1.zip"

Oh my.

 

[elektrownik]

oil fire ? but where is ignition source ? reactor was without power source so only hot thing could be fuel...

 

[SteveElbows]

I know I was moaning a lot the other day about people posting images from the live feed and getting hopelessly carried away with ideas about what they are seeing, but now I am going to do the same!

The attached picture was captured from the live feed by me about 10 minutes ago. Whats up with unit 2 building and the large dark rectangle on the west wall?

 

[elektrownik]

I know I was moaning a lot the other day about people posting images from the live feed and getting hopelessly carried away with ideas about what they are seeing, but now I am going to do the same!

The attached picture was captured from the live feed by me about 10 minutes ago. Whats up with unit 2 building and the large dark rectangle on the west wall?

This is big crane under damaged roof, but it is unit 1 not 2

 

[quark42]

Anyone use .docstoc? Can you open this link for this document... http://www.docstoc.com/docs/7254461/Reactor-Pressure-Vessel-Issues-Printable-Version

Here's the link to the PDF at the NRC's site: http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/prv.pdf"

First post here. I've been reading this thread since around the #350th post and I'd like to thank all the contributors. I've learned an incredible amount about nuclear physics and the engineering of nuclear reactors.

Keep up the good work. Back to lurking...

 

[MiceAndMen]

I know I was moaning a lot the other day about people posting images from the live feed and getting hopelessly carried away with ideas about what they are seeing, but now I am going to do the same!

The attached picture was captured from the live feed by me about 10 minutes ago. Whats up with unit 2 building and the large dark rectangle on the west wall?

I think the dark rectangle is the south wall of unit 1. Have a look at this new picture from the set recently posted:
http://www.flickr.com/photos/xtcbz/5705865264/in/set-72157626687253144/

Unit 2 looks fine.

 

[SteveElbows]

This is big crane under damaged roof, but it is unit 1 not 2

Aha yes, thanks, I made a very simple and stupid mistake. Sorry about that!