Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Dmytry]

How sure are you that there's working 'scram on first tremors'?
Anyways, it really doesn't tell anything we don't already know. The ratio of isotopes is wrong. Ditto for sfp #4 . We know that and we have enough expertise. Of course some can postulate unknown chemical mechanisms that would result in such ratio, and of course normally you test for criticality by checking for shorter lived isotopes, and so on and so forth. So it is still possible to plausibly deny criticality, so what, it's not a plausible denial contest here. The criticality is a big deal and has to be assumed until it is shown that there is no criticality.

edit: also, they could add some crap to cooling water, something that would transmute when absorbing neutrons. Then test for it's products of transmutation. That wouldn't even rely on the leaching of isotopes from the fuel, and with addition of amount of stable isotope of the element that test transmutes into, to be able to know the dilution rate, accurate analysis can be performed and the rate of fissioning calculated. (Of course they're never going to do this. This method I just made up. A lot of methods can be invented for testing for criticality)

 

[thewatcher]

My comments were based on the right half of this image from a previous post, allegedly a photo taken after the earthquake (and tsunami?) but before the #4 explosion:

[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/reactor4-S-7.png

In this photo the staircase seem to be still there, whereas the Mysterious Green Box has been replaced by the Mysterious Hole With Mickey Mouse Ears.

Note that the "Dark Goo Flowing Down From The Terrace" is already there.

Just wanted to say thanks for the knowledge and a great thread. Have just been reading for days. The only thing I want to add is a term for that Dark Goo Flowing that is beginning to appear around the net and seems appropriate. That dark goo is being called Poolium. Seems most appropriate.

Thanks again for all the analysis. Back to watching, learning and reading.

Credit goes to an 815 page thread on ATS here by JustMike
http://www.abovetopsecret.com/forum/thread672665/pg681

 

[Jorge Stolfi]

... the report I was reading concluded a predicted design flaw or weak area was proven during the test (guide pin areas?? Not sure). So anyway, I was thinking if a leak occur at the cap and flange, high pressure steam and accompanying heat is capable of 'slicing' through reinforced concrete just depends where it's directed. Also, if I read the diagram correctly, there is a gasket or 'O' ring between the two flanges that would be the first thing to fail with overheating.

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

 

[MiceAndMen]

Starting with Unit 1...

By adding numbers from the blueprint I got 41.560 x 41.560 for the ground floor, 31.420 x 41.560 for the service floor (at the external wall surfaces). For the total height (from ground floor to upper side of roof, not counting the parapet) I get 44.400 m.

Those are the same numbers for length and width I've been using as my yardstick (is there such a thing as a meterstick?). For the height I've been using 44.75 m. which looks to be the level of the main roof on those diagrams. The parapet, which I take to be 500 mm wide, probably adds between 200 and 500 mm to the absolute upper elevation.

As for Units 2-4...

My estimates, from the blueprints and sketches shown in my pevious post, are 47.8 x 47.8 m for the ground floor, 35.8 x 47.8 for the service floors (at the external wall surfaces). Total height (from ground floor to upper side of roof, no counting the parapet) is given as 45.520 m.

I calibrated a couple of the high-resolution images in Autocad using the above measurements for Unit 1. All of the photos available are from oblique angles, however, making it difficult to be precise about anything else. Perspective seems to be present in some pictures while others lack it. I attribute that to different cameras.

My best estimates for length and width of Units 2-4 is 47 m (a square) at the base with the narrow upper floors 35 m wide, but 35.8 x 47.8 is within my margin of error, which is considerable. Tomorrow I plan to see if the site map MadderDoc extracted from the TEPCO radiation reports can help refine my estimates.

 

[Most Curious]

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

I am far from an expert so will happily defer to one if they show up! Hopefully they will correct my errors.

The "washer" or refuel seal does have manholes. I assume they are open except when refueling requires the reactor well to be flooded. I would assume that considerable stress occurs as the reactor "grows" when heated to operating temperature.

The "maintenance door" is also known as an equipment hatch to move stuff into the DW. Obviously needed to service relief valves, recirculation pumps and pump isolation valves, among other things. The picture of Brown's Ferry under construction shows the hatch quite clearly. I understand the DW is a miserable and very crowded work space.

The vent pipes between the SC & DW are always open but do include a vacuum breaker. There is a bellows in the drain or vent lines between the DW & SC. (In my non-expert opinion a bellows may be damaged and leaking on unit 2 as it has the lowest failure pressure of the DW & SC components.)

 

[MiceAndMen]

The "maintenance door" is also known as an equipment hatch to move stuff into the DW. Obviously needed to service relief valves, recirculation pumps and pump isolation valves, among other things. The picture of Brown's Ferry under construction shows the hatch quite clearly. I understand the DW is a miserable and very crowded work space.

The vent pipes between the SC & DW are always open but do include a vacuum breaker. There is a bellows in the drain or vent lines between the DW & SC. (In my non-expert opinion a bellows may be damaged and leaking on unit 2 as it has the lowest failure pressure of the DW & SC components.)

This Mark I photograph is one of my favorites. It's the Browns Ferry 1 unit under construction in 1966. Both drywell and wetwell (torus) are clearly shown.

http://upload.wikimedia.org/wikipedia/commons/3/36/Browns_Ferry_Unit_1_under_construction.jpg

You can get a good sense of scale by looking at the man walking around the upper rim. Front and center there is what looks like an access hatch/airlock that would permit entry after the whole thing is encased in concrete. Further to the right there is a larger diameter hole; not sure whether this would be permanently sealed after construction. No bellows visible on the torus connecting pipes, but I'm sure they are there somewhere.

For what it's worth, anyone of the many drywell penetrations could provide a path for hydrogen to escape into the interior of the containment building if seals/valves/welds break in the wrong time and place.

Construction details differ between Browns Ferry 1 and Fukushima Daiichi. All are GE BWR4 reactors, but Browns Ferry 1 was designed to generate almost 50% more power than Fukushima Daiichi units 2-5. Maybe an expert could say if that means a 50% larger primary containment. I'm no expert but my guess would be 'yes' if only because the torus would need to be larger to accommodate more steam after the larger RPV ruptured. Physical dimensions might not scale linearly with power output, however.

http://www-pub.iaea.org/MTCD/publications/PDF/CNPP2010_CD/pages/AnnexII/tables/table2.htm

 

[razzz]

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

Jorge: All I know is that heat rises and in this containment concept it is expect that over-pressure contaminates travel down to get scrubbed in water then remaining gas borne contaminates travel through entrapment filters before exposure to the environment (needs electricity to perform this function). This concept is ***-backwards. Due to its massive size, you'll have pressure differentials just from height measured from the torus water level to the upper part of the containment cap. I don't see how or why you would want to gate the 6 foot diameter pipe(s) leading to the torus as the pipe protrusions purposely violate the containment shell. When the system is failed it is measured as ambient.

I'm getting a headache but here is reading material that might answer your questions and a pic. Look and see where the weak points might be and remember just how large these contraptions really are.

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf"

 

[MadderDoc]

The Mysterious Green Box should be at least 6--7 m tall to match the height of the Mickey Mouse Ears. On the other hand, judging by the ground-level photo below, the Big Green Closet may be quite a bit taller than that. (The terrace is 17 meters above ground level.)

But, the Mysterious Green Box does not have to match the height of Mickey Mouse, nor the distance between his ears. Green Box was hung on the wall,
elevated from the base of the east wall, whereas you measure the height of Mickey Mouse from the base of the wall. And, when Green Box came off the wall it appears to have taken bits of the wall panel above it, off with it.

That Big Green Closet you are looking at, I can't see what it is, but I agree that it is much too tall to be the Mysterious Green Box. I thought you were looking at this more humble bit, at the foot of the wall.

 

[MadderDoc]

I thought I read TEPCO was doing a balancing act for SFP #4, trying to keep the weigh factor down with less water and their figures of re-watering were inline with boil off losses. So they allow the pond to get so hot but not to hot and still keep coverage over the fuel assemblies. In the meantime, they try to figure out if there is a leak or not. First there is then there isn't.

I am also not sure what the strategy is with this. Perhaps one cannot have a strategy in such a situation? If I have a kettle boiling on a stove which I cannot turn off, and I don't want it to boil, I may top it with cold water each time it starts boiling -- that cools it down, stops the boiling. But I risk ending up with a full, boiling kettle. After that there's only to pray for it to leak, so I can get to add more cold water and stop its boiling.

 

[mikefj40]

There is a bellows in the drain or vent lines between the DW & SC.

The torus cutaway shows the bellows. Page 35 of this deck. http://fairewinds.com/content/how-did-general-electric-ge-mark-1-bwr-reactors-end-creating-such-world-wide-tragedy

 

[GJBRKS]

Ongoing criticalities at Unit 2?

http://www.glgroup.com/News/TEPCO-D...e-Leaking-Fukushima-Daiichi-Unit-2-53751.html

And so with unit 3 . I-131 has been rising exponentially for the last 7 days :


[PLAIN]http://img534.imageshack.us/img534/412/unit3.jpg

source : http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110428e14.pdf

The data shows to me that there is a lot of in- and outflow of material within these drains

 

[zapperzero]

http://de.wikipedia.org/wiki/Edmund_Lengfelder
All work at the reactor are unnecessary.
Are only means to avoid the radiation exposure of people and staff.

The glacial pace of operations and the low headcount on-site do, indeed, point to the idea that TEPCO is indeed acting from these principles.

I.e. they gave up on day one, because their modeling told them that, beyond those eight hours on battery power, meltdown is inevitable.

 

[Jorge Stolfi]

An underwater video of the #4 SFP (110428_1.zip) was recently posted on this thread.
I extracted the frames with

ffmpeg -i video.mpg -vcodec png frames-b/%08d.png

(The "-vcodec png" option and png output format apparently gives better images than the default extraction to JPEG format; the latter has a good amount of the 8x8 JPEG block noise).

Then I randomly picked 10 successive frames (90-99), aligned them manually, averaged them, and applied some brightness/contrast correction to each channel. Here is the result:
[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/avg-090-099-c.png
I am sure one can get much sharper images out of that video, with better processing tools. (Again, I don't see why one should take a low-res video from a static target, rather than a few high-res photos. Sigh.) There is much image deformation by thermal gradients in the water; the water must be boling inside some racks.

Some notes:
[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/out/avg-090-099-c-A-i.png

(A) These bumps on the rack edges are normal features of the racks, correct? Why do the ones in row n-2 look different from those in row 2?

(B) This streak is the result of averaging the motion of a floating object (paint flake?)

(C) Osama bin Laden, no doubt about it.

EDIT: It turns out that frames 90-99 are particularly bad. Frames 40-63 are much better. I should try again with those.

 

[razzz]

Quakes are numerous and close by.

 

[Dmytry]

The glacial pace of operations and the low headcount on-site do, indeed, point to the idea that TEPCO is indeed acting from these principles.

I.e. they gave up on day one, because their modeling told them that, beyond those eight hours on battery power, meltdown is inevitable.

no, no. Had they done that, they'd have vented right away and started seawater cooling. Before the fuel was damaged. There would have been a lot less radioactivity release.

 

[~kujala~]

I repost the graphs for clarity:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110428e14.pdf

As i got no answer on my question i ask it again: don't you find these numbers globally high comparing them to the water samples of SFP 4?

Well the first thing is to compare unit 4's sub-drain values with the unit 4 SFP values and try to see if there is something wrong. I tried that...

As for the sub-drain:
The first data I found was from 6th of April.
The last data I found was from 27th of April.

Here are the absolute values in Bq/cm3:

Date: 6th - 13th - 16th - 18th - 20th - 22nd- 25th - 27th
I131: 24 - 17 - 13 - 7,9 - 79 - 0,53 - 0,093 - 0,049
Cs134: 1,8 - 2,7 - 2,7 - 0,86 - 7,9 - 0,37 - 0,12 - 0,12
Cs137: 1,9 - 2,7 - 2,7 - 0,92 - 7,9 - 0,4 - 0,13 - 0,13

Something strange is happening on the 20th of April.
Suddenly all values increase dramatically from 18th of April and only two days after (22 nd) the values decrease dramatically:
I131: 7,9 -> 79 -> 0,53
Cs134: 0,86 -> 7,9 -> 0,37
Cs137: 0,92 -> 7,9 -> 0,4

But if we look the overall trend it is decreasing all the time. So it is really strange to have this sudden peak which goes away only after two days.
Is it possible that the measurements for the 20th of April are invalid for the unit 4?

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e15.pdf

As for the SFP:
Here are the absolute values in Bq/cm3:

Date: April 13th - 28th
I131: 220 - 27
Cs134: 88 - 49
Cs137: 93 - 55

If we compare the maximum values for the SFP and the sub-drain the values for the sub-drain are lower:

Isotope: SFP - Sub-drain
I131: 220 - 79
Cs134: 88 - 7,9
Cs137: 93 - 7,9

And if we question the sub-drain values for the 20th of April the maximum values for the sub-drain might even be less.

If sub-drain water in the unit 4 is ultimately coming from unit 4 SFP I would say these values are on par with each other. What do the experts think?

 

[PietKuip]

Here's your fresh news: http://online.wsj.com/article/BT-CO-20110429-708521.html" .

Some more info about the resignation by Toshiso Kosako: http://www.forbes.com/feeds/ap/2011/04/30/general-as-japan-earthquake_8443174.html

In a tearful news conference, Kosako said he could not stay and allow the government to set what he called improper radiation limits of 20 millisieverts an hour for elementary schools in areas near the plant.

"I cannot allow this as a scholar," he said. "I feel the government response has been merely to bide time."

Kosako also criticized the government as lacking in transparency in disclosing monitoring of radiation levels around the plant, and as improperly raising the limit of radiation exposure levels for workers at Fukushima Dai-ichi, according to Kyodo News agency.

But I am quite certain that he must have said "20 microsieverts per hour"...
Edit: Should have been 20 millisieverts per year - see https://www.physicsforums.com/showpost.php?p=3275885&postcount=5433 by Azby.

Edit: an apt metaphor:
"The prime minister's office and administrative organizations have made impromptu policy decisions, like playing a whack-a-mole game, ignoring proper procedures," the radiation expert said.
http://mdn.mainichi.jp/mdnnews/news/20110430p2g00m0dm018000c.html

 

[fluutekies]

no need to guess ;-) the factor is ~1.5 (http://en.wikipedia.org/wiki/Compound_interest: e^0.41)

Thanks! Agreed.
So we have a more precise leak rate of SFP#4 of ~35 L/min = ~45 m3/day for the period from 13 - 28 April. As the dilution is exponential, it should be possible to estimate the begin amount of Cs-137 after the accident.

 

[htf]

no need to guess ;-) the factor is ~1.5 (http://en.wikipedia.org/wiki/Compound_interest: e^0.41)

How did you calculate this factor?

When I assume constant flow in and out, I get leak rate of 0.5 l/s = 30 l/min = 43 m³/day.

 

[fluutekies]

How did you calculate this factor?

The model assumes a stirred reactor with constant in & out flow. The concentration / number of dissolved particles in this volume then decreases exponential according e^(fraction lost particles) = e^0.41. (0.41 = 100% -59% from the previous estimation)

To remove all particles or dilute to concentration --> 0, e^(fraction lost particles) --> infinite. It's analogous to radioactive decay, a 1st order reaction.

But remember: All models are wrong, only some are useful. Or for the older generation, the "Profumo-rule": Don't play with models! ;-)

EDIT: My math sucks. To be continued ...

 

[SteveElbows]

This Mark I photograph is one of my favorites. It's the Browns Ferry 1 unit under construction in 1966. Both drywell and wetwell (torus) are clearly shown.

http://upload.wikimedia.org/wikipedia/commons/3/36/Browns_Ferry_Unit_1_under_construction.jpg

May I also recommend this excellent film which shows construction at Fukushima (reactor 1 I presume).





A few minutes into the first part you will see quite a lot of construction work including the assembly of the drywell, some work inside the torus, pouring of concrete round the drywell and manufacture and installation of the reactor pressure vessel. At around 6 mins 40 seconds a plate with holes in can be seen, do we think this could be the plate that the control rods pass through?

edited to add that towards the latter stages of part 2, can see people coming through a door that is familiar to us from the robot videos. Also I may not be able to understand the narration but the music is superb in places, and I wish this film was available in higher res as it is visually quite stunning.

 

[Dmytry]

Math:
When the water is leaking from the pool and fresh water is being re-introduced at a rate of x litres per unit time, and the volume of pool is v , and amount of salts is c, the amount decreases as:
dc/dt=-c*x/v
Equation of concentration is then
c=c0*e^-t*x/v
(to doublecheck, differentiating both sides gives dc/dt=c0*e^-t*x/v *-x/v = -c*x/v)
so we have:
e^-t*x/v = 0.59
-t*x/v = log(0.59)
t*x/v=0.3 edit: actually, 0.53 , used Google calculator and there log is a base-10 logarithm.
meaning 0.53 of the spent fuel pool volume has leaked out in that time period where the concentration decreased to 0.59 of original value. That is ignoring any extra cs-137 that may have leached from the fuel during that time.

 

[triumph61]

But, the Mysterious Green Box does not have to match the height of Mickey Mouse, nor the distance between his ears. Green Box was hung on the wall,
elevated from the base of the east wall, whereas you measure the height of Mickey Mouse from the base of the wall. And, when Green Box came off the wall it appears to have taken bits of the wall panel above it, off with it.

That Big Green Closet you are looking at, I can't see what it is, but I agree that it is much too tall to be the Mysterious Green Box. I thought you were looking at this more humble bit, at the foot of the wall.

A better Picture

 

[SteveElbows]

I've been trying to make sense of pool water levels by doing some graphs showing the water level and the amount of spraying. Sometimes it seems to make sense but other times it does not. This makes me question the reported water level. Is it safe to assume that the Fuel Pool Cooling Skimmer Surge Tank levels are a good indication of water level in the actual pool?

On a related note I see that reactor 1's FPC Skimmer levels have started to drop in recent days. This reading was steady at 4500mm for the many days that this data has been published, but it went up to 4550mm on the 25th, dropped to 4200mm on the 27th, 3700mm on the 28th, 3000mm on the 29th and the figures for the 30th show it is down to 2600mm!

 

[rowmag]

Updated sub-drain isotope level measurements as of 4/30:

http://www.tepco.co.jp/cc/press/betu11_j/images/110430l.pdf

 

[fluutekies]

Math:
When the water is leaking from the pool and fresh water is being re-introduced at a rate of x litres per unit time, and the volume of pool is v , and amount of salts is c, the amount decreases as:
dc/dt=-c*x/v
Equation of concentration is then
c=c0*e^-t*x/v
(to doublecheck, differentiating both sides gives dc/dt=c0*e^-t*x/v *-x/v = -c*x/v)
so we have:
e^-t*x/v = 0.59
-t*x/v = log(0.59)
t*x/v=0.3
meaning 0.3 of the spent fuel pool volume has leaked out in that time period where the concentration decreased to 0.59 of original value. That is ignoring any extra cs-137 that may have leached from the fuel during that time.

Thank you for the fast math!

One correction:

e^-t*x/v = 0.59
-t*x/v = ln(0.59)
t*x/v=0.53

meaning 0.53 of the spent fuel pool volume has leaked out in that time period where the concentration decreased to 0.59 of original value. That is ignoring any extra cs-137 that may have leached from the fuel during that time.

Based on this model, assumptions & correction, the leak of SFP#4 could be

~ 42 m3/day or 1.8 m3/h or ~29 L/min

 

[Azby]

<But I am quite certain that he must have said "20 microsieverts per hour"...>

Actually, it's 20 millisieverts per year. As per this Gov't statement (sorry, in Japanese, and pretty impenetrable even in Japanese...):

http://www.mext.go.jp/b_menu/houdou/23/04/1305174.htm

And this protest by Greenpeace:

http://www.greenpeace.org/international/en/press/releases/Greenpeace-condemns-move-to-raise-radiation-exposure-levels-for-Japanese-children/

See this map for reference:

http://www.mext.go.jp/component/a_menu/other/detail/__icsFiles/afieldfile/2011/04/26/1305519_042618.pdf

(First page map shows levels measured on April 24 in microsieverts/hr; second page map shows predicted 1st year doses in mSv. This provides more detail for the NSSA/DOE map of April 18)

BEIR VII predicts that 20mSv/yr will give about 0.2% increased risk of cancer/yr (so about 2% in 10 yrs, 6% in 30 yrs). The Japanese gov't justifies their decision by assuming children will be indoors 16 hours per day. I'd prefer them to be more cautious. I'd have less problem with a similar policy for areas getting 10mSv/yr, as long as residents were clearly informed of the risk parameters and allowed to opt out with full compensation.

 

[Dmytry]

Thank you for the fast math!

One correction:

e^-t*x/v = 0.59
-t*x/v = ln(0.59)
t*x/v=0.53

meaning 0.53 of the spent fuel pool volume has leaked out in that time period where the concentration decreased to 0.59 of original value. That is ignoring any extra cs-137 that may have leached from the fuel during that time.

Based on this model, assumptions & correction, the leak of SFP#4 could be

~ 42 m3/day or 1.8 m3/h or ~29 L/min

Ahhh... yea I meant natural logarithm of course. Used the Google to calculate, and in programming the ln is typically called 'log'
http://www.cplusplus.com/reference/clibrary/cmath/log/
The number did feel wrong. Should start always using wolframalpha instead, it shows how it understood you.
edit: interesting...
http://www.wolframalpha.com/input/?i=log(0.59)

 

[MadderDoc]

An underwater video of the #4 SFP (110428_1.zip) was recently posted on this thread.
I extracted the frames with

ffmpeg -i video.mpg -vcodec png frames-b/%08d.png

(The "-vcodec png" option and png output format apparently gives better images than the default extraction to JPEG format; the latter has a good amount of the 8x8 JPEG block noise).

I use Avidemux to extract frames from videos and can heartily recommend it. It allows you to easily skip forwards and backwards, frame to frame, or keyframe to keyframe, and pick a good target frame or a frame range. The selected frame(s) can be dumped to the disk as bmp or jpg, quality is good (but of course depends on your renderer.

Then I randomly picked 10 successive frames (90-99), aligned them manually, averaged them, and applied some brightness/contrast correction to each channel. Here is the result:
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/avg-090-099-c.png
I am sure one can get much sharper images out of that video, with better processing tools. (Again, I don't see why one should take a low-res video from a static target, rather than a few high-res photos. Sigh.) There is much image deformation by thermal gradients in the water; the water must be boling inside some racks.

I think perhaps this video has been shot with a camera slightly above the surface, with submersed lighting from the sides of the camera. The apparent visually disturbing thermal gradients may in fact be motion of the water surface, the camera is looking through.

I have attached the best frame I could find using Avidemux. After extraction of the frame, the color levels have been adjusted using Gimp. (The video wastes a lot of its color levels in the shade, where very little information is contained.

As criterium for 'best frame' I used the position digits stamped into the racks , in the best frames I found these are readable (but only barely), while in most frames you cannot see that there are digits at all. It is clear that some of the stuff moving about is debris, but just as clear that some of them are bubbles. This becomes particularly clear when skipping framewise backwards with Avidemux. in reverse you see the bubbles _dive_, in the wiggling fashion so typical for bubbles, to disappear into crevices below.

Some notes:
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/out/avg-090-099-c-A-i.png

(A) These bumps on the rack edges are normal features of the racks, correct? Why do the ones in row n-2 look different from those in row 2?

I think these 'bumps' must be for handling the racks. I am not sure that the bumps in rack no 2 and rack no 7 look different. They do look much alike to me.

(B) This streak is the result of averaging the motion of a floating object (paint flake?)

This object becomes clearly visible from about frame 60 moving towards the upper left. By tracking its motion there's no clear indication of bubble behaviour, it could be a paint flake, or some other low density debris.

(C) Osama bin Laden, no doubt about it.

LOL

 

[Dmytry]

on topic of the video, check the grid in topleft corner. Very visibly damaged. Looks like sagging of aluminium near the melting temperature.

edit: also the camera is clearly underwater... it is entirely off focus until it goes underwater, as you would expect from a camera that can only shoot underwater (needs correct index of refraction).
And in the end you can see so much waving, you wouldn't be able to see so clearly through such waving with camera above water.

 

[MadderDoc]

I've been trying to make sense of pool water levels by doing some graphs showing the water level and the amount of spraying. Sometimes it seems to make sense but other times it does not. This makes me question the reported water level. Is it safe to assume that the Fuel Pool Cooling Skimmer Surge Tank levels are a good indication of water level in the actual pool?

On a related note I see that reactor 1's FPC Skimmer levels have started to drop in recent days. This reading was steady at 4500mm for the many days that this data has been published, but it went up to 4550mm on the 25th, dropped to 4200mm on the 27th, 3700mm on the 28th, 3000mm on the 29th and the figures for the 30th show it is down to 2600mm!

That's a very interesting observation, Steve. Do you have access to data for the sprayed amount to SFP1 over time? (I scanned the Tepco press releases, but could find reference to sprayings to SFP1 only on March 31st).

If I understand the arrangement with the skimmer surge tank, once water level in the pool goes below some level, the system becomes compartmentalized, and the level in the skimmer surge tank will no longer be an indication of the level in the pool.

 

[MadderDoc]

on topic of the video, check the grid in topleft corner. Very visibly damaged. Looks like sagging of aluminium near the melting temperature.

edit: also the camera is clearly underwater... it is entirely off focus until it goes underwater, as you would expect from a camera that can only shoot underwater (needs correct index of refraction).
And in the end you can see so much waving, you wouldn't be able to see so clearly through such waving with camera above water.

I am not sure the grid in topleft corner is actually a fuel assembly rack. Compared to what is clearly racks elsewhere, this one has other dimensions.

My interpretation of the waves seen at the end is they are produced as the camera arrangement is withdrawn, when the submersed lighting sources breaks through the water surface. Once the light sources are out of the water, the camera becomes unable to focus on anything inside the pool, so it tries to focus in stead on the reflections of light from the surface.

 

[MadderDoc]

A better Picture

Yes, of the Big Green Closet Jorge is talking about, this is a much better photo. It appears to me to be some sort of ladder arrangement, either meant for support of something above it, or for affixing wiring. It looks blue to me. The smaller green box-like object which may be at the foot of the wall is not visible in this photo, it is hidden behind the debris in the foreground.

 

[rowmag]

I am not sure the grid in topleft corner is actually a fuel assembly rack.

NUCENG has already told us that it is not:

https://www.physicsforums.com/showpost.php?p=3274544&postcount=5370

 

[Dmytry]

I am not sure the grid in topleft corner is actually a fuel assembly rack. Compared to what is clearly racks elsewhere, this one has other dimensions.

the point is, it looks visibly damaged, the lines of grid are not straight and it is so in the video, not just some transient distortion.

edit: ahh, you meant the other grid with big holes? Ignore it. Definitely not a fuel rack. I mean, on the left side of the top of the video, near middle. There's another something on the topright, its not visibly damaged.

My interpretation of the waves seen at the end is they are produced as the camera arrangement is withdrawn, when the submersed lighting sources breaks through the water surface. Once the light sources are out of the water, the camera becomes unable to focus on anything inside the pool, so it tries to focus in stead on the reflections of light from the surface.

There's just too little waving in the video for the waves we see in the end. Does not look anything like look through waving water surface.

edit: also. This thing been cooled by salt water, and there's fresh water pouring in. Of course there will be a lot of 'shimmer' that is not from temperature differences, but from salinity differences