Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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.

 

[bytepirate]

It look like the shadow from the tower left side

could be the shadow of the tower on something else.

but then again - i have clearly spotted winnie the pooh and a triangel-faced alien on the aftermath closeup photo of the same area, that was posted earlier in this thread ;-)

 

[Cainnech]

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.

March 12, 2011 ?

http://www.flickr.com/photos/beaconradio/5519735150/in/set-72157626118689013
highest resolution available: http://farm6.static.flickr.com/5014/5519735150_d55488e3c2_o.jpg

Looks to me that the photos were taken at the same occasion.

 

[ascot317]

March 12, 2011 ?

http://www.flickr.com/photos/beaconradio/5519735150/in/set-72157626118689013
highest resolution available: http://farm6.static.flickr.com/5014/5519735150_d55488e3c2_o.jpg

Looks to me that the photos were taken at the same occasion.

It's not the shadow for sure. Likely something related to the maintenance. But was it ab additional safety related system or not?

 

[Borek]

highest resolution available: http://farm6.static.flickr.com/5014/5519735150_d55488e3c2_o.jpg

From this picture it is obvious it is not shadow of the tower - shadow is visible in the different place.

Edit: beaten by ascot.

 

[GJBRKS]

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

03:50 pm February 10th : A leak in reactor 4 , 2 liters of contaminated water was found during periodic inspection ...

 

[triumph61]

March 12, 2011 ?

http://www.flickr.com/photos/beaconradio/5519735150/in/set-72157626118689013
highest resolution available: http://farm6.static.flickr.com/5014/5519735150_d55488e3c2_o.jpg

Looks to me that the photos were taken at the same occasion.

You can find the Foto here:

http://tupian.hudong.com/29105/25.html?prd=zutu_thumbs

 

[tyroman]

@Jorge Stolfi

Great work on the renderings!

At your post:
https://www.physicsforums.com/showpost.php?p=3275086&postcount=5393
You say/ask:
"However, the flanges connecting shroud and drywell seem to be rather massive things held together with a zillion heavy bolts. So I would expect that the walls of the drywell will rupture at some weld somewhere else, well before the bolts do. Is that correct?"

See page 5 of 7 in attached DOE-leakage study.pdf where it says;

"For the BWR Mark I -- a leak area of 35 sq in was estimated at -- 117 psig --. Most of this leak area (approximately 95%) is attributed to the drywell head which is predicted to unseat at a pressure of 27 psig."

The study described in the attached pdf "concentrated on identifying potential leakage paths that may occur prior to reaching currently reported containment shell capability pressures."

In other words, at a containment pressure [117 psig] which is much less than the design strength of the steel containment, the drywell head will unseat and leak.

@razzz

Is the above DOE-leakage study.pdf the report you remembered?

.

 

[MadderDoc]

March 12, 2011 ?

http://www.flickr.com/photos/beaconradio/5519735150/in/set-72157626118689013
highest resolution available: http://farm6.static.flickr.com/5014/5519735150_d55488e3c2_o.jpg

Looks to me that the photos were taken at the same occasion.

It certainly does. The photo must have been taken after the tsunami, and before the debris on the road by that orange crane was cleared. From the direction of sunlight, the time of day would appear to be in the morning, about 8 am. The clearness of the sunlight is inconsistent with the weather conditions in the morning of March 13th. This really leaves us with no other choice than to accept the date to which it is attributed, March 12th.

 

[SteveElbows]

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.
[PLAIN]http://gyldengrisgaard.dk/fuku_docs/sfp4_rackdamage.bmp[/QUOTE]

Having stared at a few captures of this video for a while,I think people should be very careful when looking for damage to the racks themselves.

If I look carefully at the racks, then it seems that there are lugs/handles which protrude higher than the rest of the rack. They can be seen most clearly on the rack that is to the right of the image, and once noticed are also easy to spot for the rack we have a full view of in the middle. As they seem to always be on the third row of fuel slots from the edge, they would also be present in just the area you have pointed to with arrows, and if not taken account of may look like distortion to the racking.

Attached is an image with pairs of these circled.

 

[Godzilla1985]

Good eye, Steve.

Now if only we could see what the rest of the SFP looks like. I'm sure TEPCO already knows...