Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MadderDoc]

@MadderDoc:
Sir - might I respectfully ask if you might consider turning your talented eyes toward the south end of Building 3 and perhaps adding your assessment of the mechanical and thermal damage to the south end of the building as well as the roof? I believe you may find similar evidence that the initial blast and thermal damage had a substantial horizontal vector as well. Thanks.

Certainly. It seems quite obvious to me that the initial blast had a substantial horizontal vector. We can see that in the video already in the very first frame that shows something abnormal is going on in the building.

In this first frame, the flash of fire has not yet risen over the building, of that we see only the top part of some smoke it has produced, at the top east side of the building where the flash of fire presumably first made exit. But concurrently, in the very same frame we see the west face of the building abruptly changing its reflective properties, consistent with its shattering. And, in the next few frames all the walls that are visible in the video appear to collapse, horizontally outwards, quite consistent with how we find wreckage and tracks of grey dust and debris after the event, cast horizontally out to the east, west and south (Indications of a similar horizontal spew at the north end are weaker, due to later events with ballistic objects messing up 'the scene of the crime'.) However, we know that in the NW corner a big machine was situated (I believe for air filtering) before the explosion. After the explosion we find this machine hanging from the wall under the panel where it was situated, apparently defying gravity, but more realistically just hanging on with its ducts and wires. This machine very unlikely could have been moved to this miraculous position by a vertical force, for that feat a horizontal force would need to be present, also at the north end of the building.

 

[jlduh]

More contamination on the grass in towns outside of the evacuation zone, and far outside!

http://www3.nhk.or.jp/daily/english/13_01.html



NOTE THAT NIKKO CITY IS AT AROUND 170 kms FROM THE PLANT (SOUTH WEST) which is quite far... the other one is at around 100 kms same direction.

http://maps.google.com/maps?f=q&sou...8424,140.542603&spn=2.548084,6.696167&t=h&z=8

It seems that the winds are spreading the bad stuff in several directions, the North west has been severely touched, the South West could start to get the same scenario.

Over a long period of time (who knows when this crisis will be contained), we can fear that long life Cs-137 (ans maybe Strontium?) will accumulate here and there, like thin layers of small snow falls which would never melt and add weeks after weeks...

The only difference being this is invisible and dangerous snow...

Some more contamination of tea leaves:

http://www3.nhk.or.jp/daily/english/13_39.html

Radioactive material above designated safety limits has been detected in tea leaves harvested in 5 municipalities in Kanagawa Prefecture, neighboring Tokyo.

The prefectural government checked samples of leaves harvested in 15 municipalities in the region. Officials say that samples from 5 of those were found to contain unsafe levels of radioactive cesium.

They say 780 becquerels of cesium were detected in tea leaves in Odawara City, 740 becquerels in Kiyokawa Village, 680 becquerels in Yugawara Town, 670 becquerels in Aikawa Town and 530 becquerels in Manazuru Town.

Damn, this info is really a breaking news to me, not because of the levels (even it there are sufficiently high to make them unsafe!) but BECAUSE OF WHERE THEY HAVE BEEN MEASURED:

KANAGAWA prefecture is south of Tokyo!

I located Odawara on this map for example:

http://maps.google.com/maps?f=q&sou...008,140.855713&spn=4.754161,13.392334&t=h&z=7

So this is around 330 kms south west of Daichi plant!

Minami Ashigara, also listed in the article, is even further

http://maps.google.com/maps?f=q&sou...0598,139.251709&spn=4.74326,13.392334&t=h&z=7

The scale at which unsafe deposits are falling is enlarging day after day...

 

[jim hardy]

"""However, what if there was recriticality in unit 3 reactor core? Would it be conceivable that after the fuel rods have been without sufficient cooling (above water level), they start heating up, melting away the control rods (borated steel, would it melt prior to the fuel pellets?), then they start injecting cooling water from outside, which cools the remains, but also acts as moderator. With control rods partly gone, the core suddenly goes critical, followed by essentially steam explosion within containment, which however, is not strong enough to destroy the drywell, but causes the spectacular explosion of unit 3 reactor building including gamma spike? ""

similar train of thought explored on this thread, on May 7 i think, its page 314 viewed in Firefox don't know about explorer. Look for two long posts by Analog, and don't miss the videos on Borax.

http://tickerforum.org/akcs-www?post=182121&page=314#new

jorge stolfi - in his second long post the guy bragged on your plots bigtime !

 

[artax]

Yes, very shocking, and I read a while back that the summer winds are usually from the East, but haven't changed yet!

 

[MadderDoc]

<..> Basically you are saying the column is moving upward at a speed sufficient such that an object at rest would experience a force due to air resistance greater than its weight?

Yes, or at least that was what I was trying to express :-) I do not think we can find anything substantial to disagree over in regards to this aspect.

 

[SteveElbows]

Tepco (in their "plan" or "roadmap") revealed that the stability of the #4 SFP was precarious, and that it was one of their top priority problems. Since then, they have talked about steel pillars filled with concrete to support it.

Yes, I noticed that when they first published their roadmap, it seemed to take a while before this detail started getting picked up and discussed in the news. But its not the same as TEPCO saying that unit 4 is leaning. We can tell just by looking at images of the building that's its not in great shape, but that's about it, and all the talk of leaning, sinking etc has driven me somewhat bonkers over the last week. I suppose I should not be surprised at Gundersen joining in, despite the immense horror of what has unfolded at Fukushima it is apparently not enough for some people, especially those with an agenda, who feel the need to hype things up.

Having said that if there was another big quake and building 4 partially collapsed, I would not be shocked, but I am not going to spend much time thinking about it unless it actually happens.

 

[etudiant]

Yes, very shocking, and I read a while back that the summer winds are usually from the East, but haven't changed yet!

What is really shocking is how little useful information about this disaster is available.
For instance, there is still no measurement available, afaik, of the overall daily airborne emissions from the site, even though that should be of central concern. These emissions will likely continue for at least the rest of the year, so their level of radioactivity will determine how large the Fukushima damage zone will be.
There is plenty of detail information, even if it is sometimes wrong, but no context.
The absence of overall perspective, either situationally or visually makes it very hard to get a coherent picture of the effort. This is probably deliberate, but the benefit of this security through obscurity approach is dearly bought. It hobbles any outside contribution and leaves the population in a state of anxious uncertainty.

 

[SteveElbows]

Doh, it seems the pit water at reactor 3 that got in the news recently because it caused sea contamination, was caused by their earlier water transfer operation:

http://www3.nhk.or.jp/daily/english/13_02.html

The company transferred radioactive water from the turbine building of the No.3 reactor earlier this month. It says during that process radioactive water leaked out from an underground pipe connected to the pit.

The company admitted in a news conference on Thursday that prior inspections to prevent leaks were inadequate.

Just how large will the catalogue of errors become by the time this situation is brought somewhat under control?

 

[TCups]

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

Absolutely roof chunks. Where would there have been concrete slabs over the vertical component of the explosion to be carried upward (unless you believe it to be part of the concrete plug over the reactor)? The concrete was in the walls and blew outward. It was the roof slab (and, IMO still possible, the FHM or parts of it) that went ballistic vertically. I still don't know the exact composition or density of the roof slab of Bldg 3. It was some type of flat slab industrial roofing over corrugated sheet metal over metal roof girders, though.

Either way, I believe something pretty heavy went up and then came down on the northwest corner of Bldg 3, this supported by video evidence, cross checked with the camera angle, and with the resulting damage. The denser, heavier ballistic objects would tend to be deflected less than the lighter stuff, though, and would be what fell on the building.

@MadderDoc
As for the reflectivity and crumbling of the walls, I suspect it was something like that, yes. But it would seem to me that a generalize hydrogen explosion strong enough to do that to reinforced concrete wall slabs would more likely have first blown the roof upward, not the walls outward, as appears to be the case. But that is only a guess. Also to be considered is the shadow that might arise from the initial blast at the southeast corner.

And I forget who asked, if the ignition of hydrogen gas exterior to the primary containment could have ignited not only the hydrogen accumulated in the upper building, but also the hydrogen in the primary containment (and maybe the torus) in retrograde fashion. I don't know but I can't exclude the possibility. My guess would be that as long as the contents of the primary containment were venting under pressure, the ignition would turn it into more of an outward blow-torch effect than a retrograde ignition and explosion going back into the primary containment. I am pretty sure whatever shot out of the primary containment was intensely hot and powerful, though, whether it was "burning" or not.

 

[SteveElbows]

I think someone had the very reasonable explanation that since it is colder at night, the steam condenses more readily, so that it appears as white clouds/fog. Someone else compared it to the cooling tower next to where they live, it strongly depends on the weather whether there is visible condensation of the steam.

Yes. Personally I've seen nothing on the live images this week that could not be explained by weather-related phenomenon.

I mention the information about fuel pool pumping & spraying times only to clarify these details, not because I am searching for an explanation for the varying visible steam on live feed myself. But it seems we are doomed to repeat this discussion nearly every day since the live feed causes new people to get overexcited by what they are seeing all the time.

 

[MadderDoc]

@TCups

This is a fortunate frame from one of the early helicopter overflies (March 16th), I thought you might be interested. It shows in close-up a quite peculiar damage to one of the upper wall pillars to the SE of unit 3, and it is almost like an abstract painting...

It has probably been the most intriguing image I've encountered in relation to unit 3. I couldn't get it off my mind, and it took a long time before I got a handle on what could have produced this damage. It's much better now, but I think, without you, Sir, I might never have figured out what it could possibly be.

 

[SteveElbows]

Can anybody remind me where to look on the net for info about the global spread of contamination?

 

[MadderDoc]

it would seem to me that a generalize hydrogen explosion strong enough to do that to reinforced concrete wall slabs would more likely have first blown the roof upward, not the walls outward, as appears to be the case. But that is only a guess.

I think the roof may well have been shattered by a hydrogen explosion, but not lifted away against gravity, the roof slab must be a very heavy structure. With the walls things seem to be different. Apparently the way they are made, a quick sharp blow from the inside will rattle them loose, and gravity will take over peeling it all off the building.

 

[biffvernon]

Can anybody remind me where to look on the net for info about the global spread of contamination?

http://www.zamg.ac.at/wetter/fukushima/

http://www.woweather.com/weather/news/fukushima

 

[ottomane]

@MadderDoc: Pls. help me, I have difficulties interpreting the pic.

What kind of damage do you see in the left picture?

 

[etudiant]

Can anybody remind me where to look on the net for info about the global spread of contamination?

One good site (in German only, sorry) is here: http://www.zamg.ac.at/wetter/fukushima/

The data is built using the Test Ban Treaty network and global atmospheric circulation, plus estimated decay rates for cesium and iodine, with a guess for initial emission levels. Xenon is not covered.
There are other sites with nice global maps, whether the data is carefully adjusted for decay and dilution is murky.
I believe Berkeley has a decent global map as well, somewhere in their nuclear forum here: http://www.nuc.berkeley.edu/UCBAirSampling

Maps are increasingly iffy, partly because the cesium is gradually drifting all over and has a long enough half life that all 2011 deposits are effectively simultaneous, but also because we do not have solid data on the amount of airborne emissions. Clearly if all three reactors have had comprehensive fuel failure, there will have been massive emissions, much more than initially thought. So there may be a permanent increase in global background radiation as a result of this disaster.

 

[MadderDoc]

http://gyldengrisgaard.dk/fuku_expl1/
http://gyldengrisgaard.dk/fuku_expl3/index.html

talking about "bulging, look closely at the frames -4 to +2 on the N°3 reactor page. To me you can actually see the south wall of the building "bulging" under internal pressure like a Coke can just before ignition and explosion (look at faint shadows, the sun position seems to help to see this)...

When I assembled those pages, I decided to put in 10 frames before something actually 'started happening', to serve as some sort of baseline. (I should perhaps have put in more baseline frames, and made a note of it.)

If you examine the video for a longer baseline you will see that there are in fact a regular pattern of 'bulging' and 'shrinking' of the images of the building between frames over several seconds before the event. So this appearance of bulging would be in the video whether the reactor had blown up or not, it's just noise, possibly from heat shimmer, possibly from the video compression.

 

[MadderDoc]

@MadderDoc: Pls. help me, I have difficulties interpreting the pic.

What kind of damage do you see in the left picture?

Another and better explanation might turn up, until then I see heat damage.

 

[mikefj40]

For instance, there is still no measurement available, afaik, of the overall daily airborne emissions from the site, even though that should be of central concern.

That seems to be the reason that NILU (Norwegian Institute for Air Research) suspended their atmospheric transport modelling. They say "We have discontinued our Flexpart forecast of the atmospheric dispersal of radionucleides from Fukushima. This due to the fact that we do not have access to reliable release rates reflecting the current situation at the plant to be used as input to our simulations. It is likely that the release of radioactive material is significantly reduced compared to the initial period, and that levels no longer pose a health risk at distance from the plant."

http://transport.nilu.no/products/fukushima/index/?searchterm=fukushima

A case of GIGO. Garbage in garbage out.

 

[AntonL]

Forgive me if this was done before, after having found the location of the camera by aligning the HV line tower with the left most stack and reactor unit 1 (https://www.physicsforums.com/showpost.php?p=3296107&postcount=6694") and the heading of the sight line being 36.04 degrees to the centre of unit 4 south wall, and taken that wall as 34 metres. We then can scale the photo of the explosion quite accurately (34 Cos 36.04 = 27.5)

As the building top is OP+55 metres making the stacks about 90 metres high from ground level.

The speed of the column rising is about 50 m/s or 180km/hour

I also added some further dimensions, showing that the roof sheets got carried up to around 150 metres above the roof top of the reactor buildings and tried to size the black object, the two white objects are about half the size.
[PLAIN]http://k.min.us/inBoDM.jpg

 

[zapperzero]

I also added some further dimensions, showing that the roof sheets got carried up to around 150 metres above the roof top of the reactor buildings and tried to size the black object, the to white objects are about half the size.
[PLAIN]http://k.min.us/inBoDM.jpg[/QUOTE]

Such neat work. Thanks a bunch.

I think it's safe to say that the big black thing is roof. Nothing else that I can think of is that big and flat.

 

[TCups]

@TCups

This is a fortunate frame from one of the early helicopter overflies (March 16th), I thought you might be interested. It shows in close-up a quite peculiar damage to one of the upper wall pillars to the SE of unit 3, and it is almost like an abstract painting...

http://www.gyldengrisgaard.dk/fuku_docs/unit3_concrete_pillar_heatdamage.jpg

It has probably been the most intriguing image I've encountered in relation to unit 3. I couldn't get it off my mind, and it took a long time before I got a handle on what could have produced this damage. It's much better now, but I think, without you, Sir, I might never have figured out what it could possibly be.

I can't quite match the two images and I don't recall the video, but . . . do you mean that the close up of the pillar looks like Salvador Dali took a giant blow torch to it?

 

[SteveElbows]

That seems to be the reason that NILU (Norwegian Institute for Air Research) suspended their atmospheric transport modelling. They say "We have discontinued our Flexpart forecast of the atmospheric dispersal of radionucleides from Fukushima. This due to the fact that we do not have access to reliable release rates reflecting the current situation at the plant to be used as input to our simulations. It is likely that the release of radioactive material is significantly reduced compared to the initial period, and that levels no longer pose a health risk at distance from the plant."

http://transport.nilu.no/products/fukushima/index/?searchterm=fukushima

A case of GIGO. Garbage in garbage out.

Thanks to you and the others who have helped me out with this subject.

Yes, I noted that the suspension of modelling caused some internet babbling via youtube video this week that was paying more attention to a Sean Connery film than the scale used on the graphics, so I thought I would have a proper look at the subject.

Given that even if proper release rate data was available they may show levels so low that such modelling lacks purpose now, I am moving on to actual data from monitoring sites around the world. That German site is certainly good for that, are there any other sources or is that the only one? I seem to recall some internet concern about various levels in the USA, is there a good site for that?

 

[TheMundun]

Hi,
This is my first post, having been a long time lurker here as I tried to catch up with the thousands of posts and absorb the information and knowledge posted here.
Having just seen that people are asking for slow motion video of the Unit 3 explosion, I should first explain that in Arnie's recent video about the Unit 3 prompt criticality event, he used some stills of that flame sent in by a viewer. I am that "viewer" and since I sent those to Arnie, I have developed a way which we can all use to do slow-motion analysis of the Unit 1 and Unit 3 explosions.
The procedure is in the linked document but to get everything to work you will need AVI format videos, converted from YouTube videos of the explosions. I have prepared the AVI videos but am struggling to upload them to a site from where you can then download them. If you have any suggestions as to where I can best post them for Physics Forum users to download, then please let me know. Alternatively you can use the method I used to prepare the AVI videos as outlined in section 9 of the document.
I will be putting more posts up shortly detailing some of the observations that I have made but first please follow this link to the document explaining how to use VLC Media player.

http://tinyurl.com/6fxdr63

More soon

Geoff

 

[MadderDoc]

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.

I think you do misunderstand it. I can well dream up a special scenario in which your statement is strictly speaking true (say one pool elevated in relation to the other giving it a higher potential energy) but I don't think that is what you mean at all.

Ideally, if you heat water at 100C and atmospheric pressure, the heat will not be storable in the water as molecular kinetic energy, the heat will be used to completely overcome the forces between molecules, i.e. water vapor will be produced carrying away with it the heat you have supplied, as latent heat of condensation, until all water has evaporated. So, in the sense I think you mean it, two equal pools of water, each at 100ºC and each under the same pressure cannot store different amounts of energy. In effect the temperature of water _is_ a measure of its (heat) energy content.

<..>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?

Certainly, but no matter the size of droplets, to make the transition it still takes 2257 kJ/kg, which in this case could be well served by the heat from the exothermic combustion.

<..>

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.

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

I think you have been well around it. For major sources that could be available to produce steam fast it boils down to (no pun intended) energy
in 'excessively hot' water (either unstably superheated water at atmospheric pressure in the pool, or superheated water under pressure within the containment), heat from the hydrogen combustion, and thermonuclear energy from the fuel in the pool (I understand it would be somewhat taboo to suggest that it could theoretically involve the fuel in the RPV, so I'll leave it there)

Perhaps useful, the heat of combustion of hydrogen is 120.1 MJ/kg, so the heat produced by the burning of appr. 20 kg hydrogen in air is equivalent to the amount of heat needed to evaporate 1 ton of water that has been preheated to 100C.

 

[mikefj40]

I seem to recall some internet concern about various levels in the USA, is there a good site for that?

The EPA's RADNET site recently spiffed up their user interface, but they provide no guidance on interpreting the gamma graph's energy ranges. If anyone on the forum can associate isotopes with energy ranges that would shed some light. http://www.epa.gov/radiation/rert/radnet-data-map.html

For those of us in the SF Bay Area, a tip of the hat to UC Berkeley's Nuclear Engineering Dept. They've been monitoring air, rainwater, tap water, grass, soil, milk and food since mid March. They're running on student labor so the reports are updated only a few times a week http://www.nuc.berkeley.edu/UCBAirSampling

 

[MadderDoc]

I can't quite match the two images and I don't recall the video, but . . . do you mean that the close up of the pillar looks like Salvador Dali took a giant blow torch to it?

Yeah :-) I thought of Salvador Dali too, when I first saw it. The frame is from the Tepco helicopter video no 2, shot on March 16th. It is in a short sequence where the camera sees nothing but steam, passing along the east wall of unit 3. Suddenly this motive appears on a couple of frames, blurred, shaken, not clear what it is, if anything at all. Then this single frame stands out sharply and intriguingly before the helicopter rushes on to unit 4.

 

[AntonL]

To the left of the explosion column we observed 3 pieces of debris crahing down. If you observe the video carefully you will note that they crash behind the middle stack, that is right back onto Unit 3, actually they just missed I marked them and you will also note that they are lying on top the large one on the part roof and the two smaller ones, on what seems to be blown out wall panels. Considering the column spacing (N-S) is about 7.5 metres then the larger piece is about 20 metres long as I measured earlier
[PLAIN]http://k.min.us/inAAjE.jpg

Also to the right of the explosion column we also note a huge piece come crashing down, but this time behind the right most part of Unit 4. [STRIKE]Drawing a sight line from the observation point in google Earth I think I can also identify this to be a roof panel.[/STRIKE] No I could not MadderDoc pointed that out

 

[MadderDoc]

To the left of the explosion column we observed 3 pieces of debris crahing down. If you observe the video carefully you will note that they crash behind the middle stack, that is right back onto Unit 3, actually they just missed I marked them and you will also note that they are lying on top the large one on the part roof and the two smaller ones, on what seems to be blown out wall panels. Considering the column spacing (N-S) is about 7.5 metres then the larger piece is about 20 metres long as I measured earlier
http://k.min.us/inAAjE.jpg

The big part you identify as a ballistic object, I'd say with no hesitation is just the somewhat hammered original roof of that part of the annexed building, the two smaller pieces you identify I've previously had trouble understanding until I looked at a pre-explosion photo and saw there used to be a raised part of the annexed building in this position before things came crashing down from the sky. I believe they are both remains of the original wall or roof construction of this raised part.

Also to the right of the explosion column we also note a huge piece come crashing down, but this time behind the right most part of Unit 4. Drawing a sight line from the observation point in google Earth I think I can also identify this to be a roof panel.
[PLAIN]http://k.min.us/jn6tTE.jpg[/QUOTE]

It is true that several pieces fell down very close to a sight line towards the SE corner of unit 4, but this piece is not one of them, it was there before the explosion.

Here are a few items which i have tentatively identified as ballistic objects at this end of unit 3.

 

[AntonL]

The big part you identify as a ballistic object, I'd say with no hesitation is just the somewhat hammered original roof of that part of the annexed building, the two smaller pieces you identify I've previously had trouble understanding until I looked at a pre-explosion photo and saw there used to be a raised part of the annexed building in this position before things came crashing down from the sky. I believe they are both remains of the original wall or roof construction of this raised part.

but it is lying on top

It is true that several pieces fell down very close to a sight line towards the SE corner of unit 4, but this piece is not one of them, it was there before the explosion.

I should have first looked at the post tsunami satellite photes - I withdray that claim and edit the post accordingly

 

[Jorge Stolfi]

Careful with these frames, they only show an integral over what happened within 1/25 s, faster dynamics will appear washed out.]

Also note that MPEG/JPEG encoding creates complicated artifacts. The shape of any detail that is smaller than 8x8 pixels is usually mangled beyond recognition. (If the detail persists unchanged over several frames you may recover some of the lost information by aligning and averaging, but that is not the case here.)

Moreover, color information is lost for objects that are too bright: the camera will just record white.

All you can tell from that pair of frames is that there was an orange or orange-white flash on the south side of the building, probably at the SE corner, about level with or above the service floor --- which is the location of the SFP. I believe it is not possible to extract further details of the flash shape and dynamics from that video.

 

[pdObq]

similar train of thought explored on this thread, on May 7 i think, its page 314 viewed in Firefox don't know about explorer. Look for two long posts by Analog, and don't miss the videos on Borax. http://tickerforum.org/akcs-www?post=182121&page=314#new

Very interesting, thanks for that cross-link, Jim! Seems like other forums might be ahead of this one in terms of brain-storming (or speculation if one wants)...

I haven't had time to look through all the details and references in those posts by that Analog guy , but if people with hands-on experience who know what they're talking about also came up with that and consider it a possibility, I almost feel a bit like knighted .

And seriously isn't recriticality inside the RPV much much more likely than in the SFP? (If one assumes something actually did go critical.)

 

[MadderDoc]

but it is lying on top

Roofs normally do.

As regards the long ballistic object, I may have a candidate for that. It is something that clearly has come from above, and has sunk deep into the annexed building at the north side of unit 3. It must be very heavy, lots of iron. See attachments.

 

[pdObq]

Another and better explanation might turn up, until then I see heat damage.

How about the rail for the big overhead crane banged against the pillar during the explosion?
(Where is it now? I don't know.)

 

[GJBRKS]

Forgive me if this was done before, after having found the location of the camera by aligning the HV line tower with the left most stack and reactor unit 1 (https://www.physicsforums.com/showpost.php?p=3296107&postcount=6694") and the heading of the sight line being 36.04 degrees to the centre of unit 4 south wall, and taken that wall as 34 metres. We then can scale the photo of the explosion quite accurately (34 Cos 36.04 = 27.5)

As the building top is OP+55 metres making the stacks about 90 metres high from ground level.

The speed of the column rising is about 50 m/s or 1800km/hour

I also added some further dimensions, showing that the roof sheets got carried up to around 150 metres above the roof top of the reactor buildings and tried to size the black object, the two white objects are about half the size.
[PLAIN]http://k.min.us/inBoDM.jpg[/QUOTE]

Your speed and height calculation would agree with a ballistic trajectory :

http://img641.imageshack.us/img641/2843/ballisticf.jpg


(Though I think you mean 180 km/hour instead of 1800)