Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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

 

[rowmag]

Here are Asahi Shimbun's annotations:
[URL]http://www.asahi.com/special/10005/images/TKY201104290546.jpg[/URL]

Labels are, clockwise from the top:
--Spent fuel assemblies, etc.
--Control rods
--Debris
--Fresh fuel assemblies
--Metal rack

 

[Dmytry]

For purpose of disambiguation what is what when discussing it (or did someone do this already) :

I'm speaking of 1 which looks damaged, looks like aluminium sagging near the melting temperature.
5 looks obviously damaged, especially the upper portion. 4 looks intact except for upper portion.

6: I don't know what it is, it does not look good, but it may naturally look like crap without needing any damage.

 

[fluutekies]

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)

I learned that in general it's LGa or for special cases like LG10 = Log and LGe = LN. But still confused about 1,000 vs 1.000 and 1 000.

In order to complete the estimations, an estimate of the begin concentration can be calculated according to:

n(0) = n(t) / e ^(-t*x/v)

with t(0) = 15-Mar-2011 then 13-Apr-2011 is t = 29 days of leaking with x = 42 m3/day from a volume SFP#4 v =1200 m3. n(t) on 13_Apr was 93 Bq/cm3 -->

extrapolated ~ 257 Bq/cm3 Cs-137 on 15-Mar-2011,
which is ~ 3 E+11 Bq or 0.3 TBq Cs-137 total in SFP#4

To be continued (calculation of mol or g Cs-137 for that decay and comparison against mol or g Cs-137 in undamaged fuel rods)

 

[SteveElbows]

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.

Unfortunately I have only seen the same data as you, and I've only seen that one reference to unit 1 fuel pool spraying too.

The reason I asked about the skimmer levels as they relate to the pool, is that in the simple diagrams I have seen the connection between the pool and the skimmer tank is very near the top of the pool.

 

[bytepirate]

Unfortunately I have only seen the same data as you, and I've only seen that one reference to unit 1 fuel pool spraying too.

The reason I asked about the skimmer levels as they relate to the pool, is that in the simple diagrams I have seen the connection between the pool and the skimmer tank is very near the top of the pool.

can't find the source anymore, but i remember, that it has been said, that the fuel in the #1 pool is very old and generates almost no heat.

 

[Jorge Stolfi]

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.

As others have observed, we can see when the camera enters the water (at frames 35-40) and comes out again (150-155).

It is not the illumination that is waving, the rack shapes get visibly distorted and magnified. And I do not think it is salinity either; the flakes show vigorous convenction, so the salt and fresh waters must be well-mixed by now.

It is clear that some of the stuff moving about is debris, but just as clear that some of them are bubbles.

Yes. Could they be steam? If the pool water near the surface is at 90 C, wouldn't steam bubbles condense before rising more than a few feet?

If they are not steam, what could it be? Too many and too late for disolved air. Hydrogen? Presumably, if the flow of water through an assembly is suffciently blocked at some point, a steam bubble will form below the block, and then fuel in that region can get arbitrarily hot.

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.

Indeed. In your sharper picture the light curved spots in row 2 (lower) resolve into a row of handles like those in row 7, and separate round spots belonging to the top of the assemblies.

 

[fluutekies]

...
extrapolated ~ 257 Bq/cm3 Cs-137 on 15-Mar-2011,
which is ~ 3 E+11 Bq or 0.3 TBq Cs-137 total in SFP#4

To be continued (calculation of mol or g Cs-137 for that decay and comparison against mol or g Cs-137 in undamaged fuel rods)

According to my calculations with t1/2 Cs-137 = 30.7 years, the decay function and Avogadro's number, an initial decay rate of 0.3 TBq Cs-137 corresponds with an amount of 7E-4 mol Cs-137 or 0.7 mmol, which is about "only" 100 mg Cs-137.

If this would be correct, not much of the initial inventory of Cs+ has been released into SFP#4.

 

[elektrownik]

I found photo, i don't know if it was posted here before. It is unit #4 view from turbine building side, there is this "something" about here was so much discusion:

 

[Astronuc]

This application may be of use in understanding the behavior/distribution of fission products.
http://energyfromthorium.com/2006/07/14/new-visualization-tool-for-decay-chains/

 

[Rive]

Agree. Here my try for quantification of the leak of SFP4 based on Cs-isotopes:

...

Cs-137
93 Bq Cs-137/cm3 on 2011-04-28
55 Bq Cs-137/cm3 on 2011-04-13
...
59% Cs-137 remains in SFP after 15 days.

Erm.

The 'original' value is the lower, so the amount of Cs is increased by 69%.

Ps.: OK, sorry - the timeline is ok, the 55Bq is from 04.28.

 

[jlduh]

The happiest news since a long time:

http://americasforum.org/archives/427

 

[Rive]

Ongoing criticalities at Unit 2?

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

The energy release of a criticality on the necessary level to produce such messed up I and Cs levels would be pretty easily noticeable.

 

[htf]

Cs decrease rate and TEPCOs theory of the broken gate to SFP#4

When calculating the leakage rate of the SFP#4 I get these formulas for the leakage rate r:

1. Refill at constant rate:

r₁ = V/t*ln(C(t)/C(0))

2. Refill only once:

r₂ = V/t*(C/C(0) - 1)

The truth is somewhere in between because TEPCO probably does a refill once or twice a day. But this does not really matter: r₁ / r₂ = 1.29.

What is more important: there is the volume V of the SFP in the formula. Now, TEPCO said that the gate between the SFP and the RPV has been destroyed. This would increase the effective volume we have to put into these formula.

With V = 1200 m³ we get a leakage rate of ~40m³/day. Adding ~70m³/day evaporation rate we get 110m³/day total loss rate which is consistent with the refill rate published by TEPCO.

But if we have to increase the volume V (I estimate a factor 3) we get much higher rates (120m³/day leakage rate + ~70m³/day evaporation rate = 190 m³/day total loss rate) which are no longer consistent with refill rate published by TEPCO.

 

[elektrownik]

Interesting data from tepco about unit 4 before earthquaqe (and also for 5 other units): http://translate.google.com/transla...pco.co.jp/nu/f1-np/state/unit4/u4_2010-j.html

 

[|Fred]

I found photo, i don't know if it was posted here before. It is unit #4 view from turbine building side, there is this "something" about here was so much discusion:

It was but with a lesser resolution. In my opinion this is the same structure , likely metalic that we are observing there.

 

[fluutekies]

Erm.

The 'original' value is the lower, so the amount of Cs is increased by 69%.

Ps.: OK, sorry - the timeline is ok, the 55Bq is from 04.28.

You are right. I messed up the dates in the posting. Here again the source: http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110429e13.pdf I will edit the posting to avoid confusion. Edit: Not possible anymore. But the calculation is still valid.

 

[fluutekies]

This application may be of use in understanding the behavior/distribution of fission products.
http://energyfromthorium.com/2006/07/14/new-visualization-tool-for-decay-chains/

Thx! Very helpful and good visualization.

Would it be fair to assume an average of 4.5% U-235 in the fresh fuel and a burn-down to 1% before putting in the SFP?

 

[Dmytry]

As others have observed, we can see when the camera enters the water (at frames 35-40) and comes out again (150-155).

It is not the illumination that is waving, the rack shapes get visibly distorted and magnified. And I do not think it is salinity either; the flakes show vigorous convenction, so the salt and fresh waters must be well-mixed by now.

What means by now? Each time they pour fresh water in, there's salinity difference.

You can just look at frames where the camera leaves the water. Instantly you see same green looking stuff (underwater things, still lit up) but a LOT more blurred and a LOT wavier. Obviously the camera is emerging from underwater, not the light.

 

[ceebs]

The happiest news since a long time:

http://americasforum.org/archives/427

Happy? I suppose that the police will know that hippies with geiger counters are on their way to their dealers.

 

[Jorge Stolfi]

I found photo, i don't know if it was posted here before. It is unit #4 view from turbine building side, there is this "something" about here was so much discusion:

Yes, Thanks! So it seems that "Big Greenish Closet" is indeed the "Mysterious Green Box", which was toppled from the terrace and is now hanging from it by cables/metal/pipes/whatever.

In the ground-level photo, it appears that the Big Greenish Closet is not resting on the ground, rather it is suspended some distance above it. So its size may indeed match that of the Mysterious Box, which appears to be some 6 meters tall at least.

The question now is when the pictures were taken. In the photo posted by elektrownik I see what appears to be debris on the ground in front of the turbine building, so that may be after the tsunami. If the earthquake didn't topple the box, then what did? The explosion in #3? (However there is also a crane in elektrownik's photo, so perhaps the "debris" are ordinary mess from a construction site and the photo is from before the earthquake.)

----------
"Always dispose of spent fuel rods properly"
--Tom Weller, Science made Stupid (1983)

 

[MadderDoc]

<..> I mean, on the left side of the top of the video, near middle.<..>

Right, I can see it now, that rack you are pointing to looks definitely damaged, and it does not appear to be from falling debris.
[URL]http://gyldengrisgaard.dk/fuku_docs/sfp4_rackdamage.bmp[/URL]

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

What I find hard to explain is the seemingly synchronous shimmering across large portions of the visual field of the camera. For this effect it would be necessary that whatever causes the shimmering, may it be heat or salinity transients, would have to be quite close to the camera. I wonder, do we have good reasons to believe there could be such sharp local eddies in the water? I do get the impression from the swirling debris in the water, that it is reasonably well-mixed -- otoh -- am I the only one that has felt this might be a 'fast motion' sequence, i.e. a sped up version of the original video in which many frames have been dropped? If so, the video would give an impression of a higher degree of mixing, than what's in reality. Dunno, perhaps this is an underwater camera.

 

[Dmytry]

<..> I mean, on the left side of the top of the video, near middle.<..>
{/QUOTE]
Right, I can see it now, that rack you are pointing to looks definitely damaged, and it does not appear to be from falling debris.
[URL]http://gyldengrisgaard.dk/fuku_docs/sfp4_rackdamage.bmp[/URL]What I find hard to explain is the seemingly synchronous shimmering across large portions of the visual field of the camera. For this effect it would be necessary that whatever causes the shimmering, may it be heat or salinity transients, would have to be quite close to the camera.

Makes sense to me. Hot water rises on one part of the pool, goes across some, goes down on other side. Fresh water stays on top.

I wonder, do we have good reasons to believe there could be such sharp local eddies in the water? I do get the impression from the swirling debris in the water, that it is reasonably well-mixed -- otoh -- am I the only one that has felt this might be a 'fast motion' sequence, i.e. a sped up version of the original video in which many frames have been dropped? If so, the video would give an impression of a higher degree of mixing, than what's in reality. Dunno, perhaps this is an underwater camera.

I'm pretty sure it is... look at frame 155 (and 153...156) .
The frames 155,156 are how it looks when the camera is very close to surface of the pool and is blocking the light so you don't see reflections. The shimmer is definitely too small for waves.

edit: also look at frames 35-37 .

 

[Rive]

I found photo, i don't know if it was posted here before. It is unit #4 view from turbine building side, there is this "something" about here was so much discusion:

Looks like some scaffold. Maybe for some repairs on the outer wall.

Maybe it was covered with something green like this :http://image.ec21.com/image/greennet/simg_GC03913493_CA03915980/PE_Nets_Scaffolding_Cover_Net_Debris_Net_Shade_Net.jpg

Such scaffold could disappear easily.

 

[triumph61]

I found photo, i don't know if it was posted here before. It is unit #4 view from turbine building side, there is this "something" about here was so much discusion:

It look like the shadow from the tower left side

 

[Dmytry]

Look at the attached picture. Bottom. Quite damaged as well. Not compression artifacts, other frames also look bad.

I think there's a lot of damage to the bottom right of the camera, outside the view, that's where the bubbles seem to be coming from, and that's where heating must be for the flow to be directed up-left.
edit: whoops didnt attach.