Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MadderDoc]

I'm not sure that it's the liner of the pool.

If it is not the twisted sfp steel liner we see there in the foreground, what else could it be?

Back in the days of the big pixel-huntings there was several tries to match various floorplans of service floors with the photos but IIRC it's still undecided if the FHM is there on the south end of the pool (covered with rubble and beams from the roof).

Er, say what? It should be evident that not even a perfectly matched floor-plan could tell us where the FHM of unit 3 ended up during the explosion.

 

[BrentLidgard]

If it is not the twisted sfp steel liner we see there in the foreground, what else could it be?



Er, say what? It should be evident that not even a perfectly matched floor-plan could tell us where the FHM of unit 3 ended up during the explosion.

I think it is a twisted ceiling beam that fell in the pool.

 

[clancy688]

This ought to keep us busy for a few hours:

http://dels.nas.edu/resources/static-assets/nrsb/miscellaneous/SekimuraPresentation.pdf

Thank you very much!

On page 22 there are I131 and C137 source terms for Unit 1-3.

I131: 7,3*10^18 Bq (TEPCO said something about 8,1*10^19 Bq...)
Cs137: 6,8*10^17 Bq

On page 52, there's something interesting about H2 production under irradiation. But I don't quite understand what they want to tell us there...

 

[MadderDoc]

I think it is a twisted ceiling beam that fell in the pool.

However, the twisted metal structure we see here in the foreground appears to be made of steel sheet-ware of an extension which we do not see in any of the structural elements of the roof.

 

[tsutsuji]

The Shika nuclear power plant, located in Western Japan was not hit by the March 11 quake and tsunami, but a number of measure are starting to be implemented to increase safety against tsunami and black out, as shown on the following diagrams and pictures : http://www.rikuden.co.jp/tousyataiou/attach/11042202.pdf

 

[zapperzero]

Thank you very much!

On page 22 there are I131 and C137 source terms for Unit 1-3.

I131: 7,3*10^18 Bq (TEPCO said something about 8,1*10^19 Bq...)
Cs137: 6,8*10^17 Bq

On page 52, there's something interesting about H2 production under irradiation. But I don't quite understand what they want to tell us there...

Well, they rule out hydrogen production through chemical reaction with Zr, as fuel rods are not damaged enough to support that. Then they say that, basically, radiolysis in water vapor is efficient enough.

 

[fluutekies]

TEPCO: Tainted water disposal may cost $650mln
http://www3.nhk.or.jp/daily/english/28_03.html [...]
Do we know anything about the process?

Here are examples of radwaste treatments
http://www.wmsym.org/archives/2008/panels/56-2.pdf

The wastewater treatment for Fukushima according to the above presentation would involve in principle:
1. water/oil-separator
2. solids separation from the water-phase by decanter/centrifuges (see page 12)
3. remaining solids in the clear water are removed by membrane-filtration (page 13 "ultra-filtration")
4. cations and anions are bounded to an ion-exchange resin and collected (page 13, "demineralization")
5. regeneration of the resin delivers the cations and anions in concentrated solution for further processing (either evaporation or precipitation)

Unfortunately, the wastewater in Fukushima contains high amounts of NaCl from the sea water, which will consume a significant part of the ion-exchange capacity.

This process IMO is the best available technology available yet. The process can be fully continuous. The ion-exchange operation can be cycled by "merry-go-round" installations (venor-supplied-systems) e.g. a turn key unit consisting of the membrane-filtration, pH-buffer/control and coupled merry-go-round ion-exchange for a capacity of 7m³/h was offered 3 years ago for about 0.5-1MEuro. Space required: ~5x5m Much larger capacities are available and are used for (nonrad) inorganic wastewater treatment with metal-recovery applications.

 

[jlduh]

Let's assume all speculation about the leaning of Unit 4 are true. Then washing out of radioactivity isn't the biggest problem IMHO.

Why is Unit 4 leaning? I don't think that the hydrogen explosions are at fault, at least not entirely. Damage is only in the upper part of the building, but leaning suggests that there's something wrong with the foundation. So the Tsunami probably damaged the building's foundation or washed away / drenched the earth. Plus the cooling water which's further adding to the mud. Basically, the Unit is leaning because it's standing not on solid earth, but a muddy field.
But what happens if there's a typhoon coming, bringing heavy rainfalls with it? Could it further damage the underground to that point, that there's some kind of an Earth slide resulting in Unit 4 collapsing?

Weather forecasts for Fukushima (the town, didn't find anything for Okuma) predict 60 l/m² during the next two days.

Current rain radar for Japan, with precipitations in mm/h and animation:

http://www.jma.go.jp/en/radnowc/

 

[v13]

Hello,

here is something I just made. I took two snapshots from http://www.youtube.com/watch?v=95a8obR2GaE" video.

It's a 3D image and it is mostly a PoC. To see it you'll need red/blue glasses. Experiment by moving closer/farther from the screen when wearing the glasses.

If you can feed me with two images which were taken with a horizontal shift (e.g. a camera from a moving helicopter) then I can compose a 3D image.

Edit: you will want to view it full-screen as in this case size helps.

 

[clancy688]

Current rain radar for Japan, with precipitations in mm/h and animation:

http://www.jma.go.jp/en/radnowc/

Thanks. I did a little math...

I assumed the whole reactor area of Units 1-4 as a rectangle of 500 * 300 metres. That's 150000 sqm. Every mm precipitation results in 150 tons of additional water.

If there's a down pour of 60 l/m2 we get 9000 additional tons of water... is that enough to overspill the trenches? I don't know how much exactly those trenches and basements can hold, but I thought it were several ten thousand tons...

 

[ThomS]

Cooling system pumps stop at Fukushima plant's No. 5 unit

Headline from the news this morning in Japan. Local TV news is reporting that a cooling pump shut down. Temperature has risen to 87-88 C. TEPCO said that they are trying to switch to a different system.

At what temp should we be really worried?

 

[westfield]

It looks like a pre-cast construction method was used for the reactor building, at least for the upper part. That would explain why the columns got toppled that easily.

Re RB3 - I'm not able to see any evidence of pre-cast concrete constuction but an abundance of evidence that it was all cast in situ, the framework and the walls. I'm not able to see any reinfoced concrete section with a clean edge that would indicate a precast construction method.

What's in the image that makes you say that and\or what's your definition of pre cast concrete constuction?

 

[dh87]

https://www.physicsforums.com/showpost.php?p=3267742&postcount=4952
The pdf document: http://www.osti.gov/bridge/servlets/purl/93598-H1kI7u/webviewable/93598.pdf

I've designed & operated an inorganic wastewater treatment unit for some years: the volumes are not the problem, but the chemical behavior of the components.
The principle is very simple: add chemicals which form (nearly) insoluble precipitates or form precipitates which adsorb or incorporate soluble ions.

In practice it will be a multi-stage process due to pH and redox-behavior. As the solubiltyproducts of the involved components are not zero, the purification is never perfect.

A typical treatment for e.g. Sr²⁺ would be addition of Na₂SO₄ to form "insoluble" SrSO₄. If the solid formed is nano-crystallinic, a co-precipitation with Fe³⁺ or Al³⁺ will form a voluminous Al/Fe(OH)₃-gel which incorporates the nano-particles. The gel is the flocculated with poly-acrylate for fast sedimentation.
The concentration of e.g. Sr²⁺ after this treatment will be 0.1-10 mg/L.

I don't think that this is good enough. The starting concentration of radioactive Sr is around 2e+05 Bq/ml (from here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110522_04-e.pdf). To calculate the concentration of Sr, where A(t) is the remaining amount and A₀ is the starting amount, t is the time, and T is the half life,

A(t) = A₀*2^(-t/T)

T = 29 years = 9e+08 sec
t = 1 sec

A(t) = 0.999999999238 * A₀

To get 1 dps

A₀ - A(t) = A₀ - 0.999999999238 * A₀ = 1

giving A₀ = 1.3e+09 atoms of Sr-90

So, 2e+05 dps/ml * 1.3e+09 = 2.6e+14 atoms/ml = 2.6e+17 atoms/l,

2.6e+17 atoms/liter / 6e+23 = 4e-07 M

4e-07 M * 88 g/mole = 4e-05 g/liter

(I hope that I didn't make too many mistakes.)

That's less than your lowest estimate for Sr precipitation. Recovery of Sr by precipitation could be greatly improved by adding non-radioactive Sr to the solution. However, you've got to be absolutely certain about what you're doing, because this will preclude using any sort of selective capture of Sr if precipitation fails.

The low concentration of Sr and of Cs makes specific capture hard as well. The Na concentration is 6 orders of magnitude higher than the Sr concentration, and something like 5 orders of magnitude higher than the Cs concentration.

 

[westfield]

Attached photo mosaic of frames from video of the unit 3 spent fuel pool. Particularly eye-catching, imo, is the apparent gross damage to the steel liner of the pool. I find it difficult to imagine how a hydrogen explosion at the service floor could have left the pool liner in this condition.

If that's the pool liner then I find it even more difficult to imagine what is now keeping the pool full of water and how the liner transformed itself from stainless steel to painted mild steel.

 

[Rive]

If it is not the twisted sfp steel liner we see there in the foreground, what else could it be?

I dunno, but I think this is the/a pool liner: http://www.tepco.co.jp/en/news/110311/images/110415_1f_4_1.jpg

Er, say what? It should be evident that not even a perfectly matched floor-plan could tell us where the FHM of unit 3 ended up during the explosion.

SFP#3 looks a bit short at its south edge - maybe the FHM is hiding there under the rubble. Could not be proven or excluded.

 

[elektrownik]

Unit 5 was >11h without cooling ?
At 9:14 pm on May 28, we confirmed temporary RHRS pumps were out of service, we started replacement of these pumps with spares at 8:12 am on may 29th

 

[Bandit127]

Unit 5 was >11h without cooling ?
At 9:14 pm on May 28, we confirmed temporary RHRS pumps were out of service, we started replacement of these pumps with spares at 8:12 am on may 29th

Longer than that.

The work began at 8.00am on Sunday (2300 GMT Sarurday) to replace the pump and it was completed in four and a half hours.

From
http://www.hindustantimes.com/New-cooling-trouble-at-Japan-nuclear-plant/Article1-703288.aspx

 

[MadderDoc]

At some time on May 28th somebody or something has removed several treetops south of the plant: Tepco's webcam facing the south wall of unit 4 now has a considerably better view to it:

 

[MadderDoc]

If that's the pool liner then I find it even more difficult to imagine what is now keeping the pool full of water and how the liner transformed itself from stainless steel to painted mild steel.

You certainly got a point there, it does not look like stainless steel. Could we be looking at parts of the top fitting to the liner of the pool, at skimmer level? I believe we see top parts of the unit3 pool wall at skimmer level in this photo taken before the disaster:

 

[MadderDoc]

<..>I think this is the/a pool liner: http://www.tepco.co.jp/en/news/110311/images/110415_1f_4_1.jpg

I am aware that this photo has been attributed in some fashion by Tepco as having something to do with a spent fuel pool, and specifically the spent fuel pool of unit 3. However it does not look to me like anything coming from unit 3, even less from its spent fuel pool or indeed from any spent fuel pool. It looks more like a pit, or a manhole.

SFP#3 looks a bit short at its south edge - maybe the FHM is hiding there under the rubble. Could not be proven or excluded.

Thank you, I see what you mean now. Indeed there would seem to be room in the rubble on the south service deck to hide the fhm or parts of it. The fhm carrying bridge otoh, is a rather much larger and stronger structure, it ought to be somewhere more or less in one piece, and I doubt that it could be hidden there too.

(But certainly the fhm and its bridge could have been dislodged from each other
in the course of the explosion, say, with the fhm ending up south while the bridge flipped over and crashed into the north end of the building.)

 

[elektrownik]

interesting, tepco change water leve injected to reactor 2, now it is 12m3/h, why ? Unit 2 is not hot...
also all temperatures in unit 3 are going up

 

[westfield]

You certainly got a point there, it does not look like stainless steel. Could we be looking at parts of the top fitting to the liner of the pool, at skimmer level? I believe we see top parts of the unit3 pool wall at skimmer level in this photo taken before the disaster:

I don't know but I would love to know what's in the shiny box next to those guys and why its oh so shiny.

 

[elektrownik]

http://www.tepco.co.jp/en/news/110311/index-e.html New photos from reactors

 

[htf]

I guess, they want to tell the press: "Look, the reactor building #4 is in really good shape!"

 

[robinson]

That reminds me. How many floors does reactor 3 building have? And how many were destroyed? Is building four the same design?

 

[Bandit127]

Unit 5 was >11h without cooling ?
At 9:14 pm on May 28, we confirmed temporary RHRS pumps were out of service, we started replacement of these pumps with spares at 8:12 am on may 29th

More detail in this article.
http://search.japantimes.co.jp/cgi-bin/nn20110529x1.html

 

[tsutsuji]

I guess, they want to tell the press: "Look, the reactor building #4 is in really good shape!"

The pictures are part of "Reports about the study regarding current seismic safety and reinforcement of reactor buildings at Fukushima Daiichi Nuclear Power Station" : http://www.tepco.co.jp/en/press/corp-com/release/11052801-e.html not yet translated into English. The erratum published today http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110529_03-j.pdf (Japanese) concerns picture captions among other things.

 

[SteveElbows]

interesting, tepco change water leve injected to reactor 2, now it is 12m3/h, why ? Unit 2 is not hot...
also all temperatures in unit 3 are going up

They are switching from fire extinguishing line to reactor feedwater line. They already did this at reactor 3, but the detail was somewhat lost because we were mostly paying attention only to the struggle against rising temperatures at reactor 3 at the time. Anyway they do this switch quite slowly over a number of days, first starting to inject more and more water through reactor feed water line, then gradually reducing water rate from fire extinguisher line. At reactor 3 there is no longer any water coming via fire extinguishing line, switchover is complete, but reactor 2 is much earlier in the switch process so for a while we will see both lines being used, and higher total flow rate.

I don't actually know why they want to switch away from fire line, I asked about this recently on this thread but nobody responded.

 

[mscharisma]

More detail in this article.
http://search.japantimes.co.jp/cgi-bin/nn20110529x1.html

From the article: http://search.japantimes.co.jp/cgi-bin/nn20110529x1.html

"Unlike reactors 1 through 4, No. 5 is less at risk of meltdown because it was not damaged by hydrogen blasts as the others were and because workers managed to restore external power to run its cooling system."

Is it just me or does the above not make sense?"The temperature of the core and the fuel pool had reached 93.6 degrees and 46 degrees, respectively, by noon Sunday compared with 68 degrees and 41 degrees at 9 p.m. Saturday.

The backup pump kicked in at 12:31 p.m. Sunday, and the temperature of the core had been brought down to 83 degrees by 1 p.m., a Tepco spokeswoman said by phone later Sunday.

The temperature must stay below 100 degrees to maintain cold shutdown status.

'We judged that it's better to wait for the morning, rather than to start working while it's dark. We didn't think it would pose any immediate danger,' Matsumoto said.

'Even if the temperature (of the core) reaches 100 degrees, the alternative water-injection system is available,' he said."

Working while it's dark? They had power at unit 5, see first quoted paragraph. And is it really okay to let the temperature rise that high without using the alternative water-injection system?

 

[elektrownik]

From the article: http://search.japantimes.co.jp/cgi-bin/nn20110529x1.html

"Unlike reactors 1 through 4, No. 5 is less at risk of meltdown because it was not damaged by hydrogen blasts as the others were and because workers managed to restore external power to run its cooling system."

Does the above make sense?

No

"The temperature of the core and the fuel pool had reached 93.6 degrees and 46 degrees, respectively, by noon Sunday compared with 68 degrees and 41 degrees at 9 p.m. Saturday.

The backup pump kicked in at 12:31 p.m. Sunday, and the temperature of the core had been brought down to 83 degrees by 1 p.m., a Tepco spokeswoman said by phone later Sunday.

The temperature must stay below 100 degrees to maintain cold shutdown status.

'We judged that it's better to wait for the morning, rather than to start working while it's dark. We didn't think it would pose any immediate danger,' Matsumoto said.

'Even if the temperature (of the core) reaches 100 degrees, the alternative water-injection system is available,' he said."

Working while it's dark? They had power at unit 5, see first quoted paragraph. And is it really okay to let the temperature rise that high without using the alternative water-injection system?

They should change pump without waitning, also there was information that pump could be damaged by salt water, so they are injecting salt water to 5 ??

 

[turi]

From the article: http://search.japantimes.co.jp/cgi-bin/nn20110529x1.html
[...]
"The temperature of the core and the fuel pool had reached 93.6 degrees and 46 degrees, respectively, by noon Sunday compared with 68 degrees and 41 degrees at 9 p.m. Saturday.
[...]
The temperature must stay below 100 degrees to maintain cold shutdown status.
[...]
And is it really okay to let the temperature rise that high without using the alternative water-injection system?

As the normal operational temperature is much higher than 100° Celcius (somewhere between 215°C and almost 295°C) that's no problem. "Cold shutdown" is just an easily remembered state you reach after some time of cooling and a state where you don't mind pressure loss that much anymore.

 

[zapperzero]

so they are injecting salt water to 5 ??

No. The salt water is from the sea, it cools the water that's used to cool the reactor.

 

[zapperzero]

I don't actually know why they want to switch away from fire line, I asked about this recently on this thread but nobody responded.

A fire line is not meant for extended periods. What fire takes two months to extinguish?

 

[Bandit127]

They should change pump without waitning, also there was information that pump could be damaged by salt water, so they are injecting salt water to 5 ??

The pump was one that pumped seawater to a heat exchanger from the sea - standard architecture for this reactor. This side is open loop. Seawater in, seawater plus some extra heat out.

The other side of the heat exchanger is closed loop and contains (as far as I know) processed (DI) water. This is the water that cools the reactor and SFP.

That they had emergency cooling systems as a backup may not make it all OK, but it does seem to be less of a problem than it first appeared.

 

[mscharisma]

As the normal operational temperature is much higher than 100° Celcius (somewhere between 215°C and almost 295°C) that's no problem. "Cold shutdown" is just an easily remembered state you reach after some time of cooling and a state where you don't mind pressure loss that much anymore.

I apologize for my completely non-scientific mind, but I thought the whole point was to keep the water temperature below 100 degrees, i.e., below boiling point, to avoid steam generation and loss of water level, etc.? What am I misunderstanding?

 

[turi]

I apologize for my completely non-scientific mind, but I thought the whole point was to keep the water temperature below 100 degrees, i.e., below boiling point, to avoid steam generation and loss of water level, etc.? What am I misunderstanding?

As in a pressure cooker the water boils at a higher temperature than 100 °C. During operation you have something like 7 MPa in the pressure vessel.

 

[Bandit127]

I apologize for my completely non-scientific mind, but I thought the whole point was to keep the water temperature below 100 degrees, i.e., below boiling point, to avoid steam generation and loss of water level, etc.? What am I misunderstanding?

You are missing pressure. Water boils at 100°C only at atomspheric pressure.

It boils at about 75°C on top of Everest and 0°C in a vacuum.

The opposite is also true, as pressure increases so the boiling point increases. To understand the relationship between boiling point and pressure, have a look at a steam table.
http://www.simetric.co.uk/si_steam.htm

This means that (for instance) water at 2 bar (i.e. atmospheric pressure x 2) boils at 120.42°C.

So, if the pressure vessel is (for instance) at 2 bar, 94°C is still quite a way from boiling.

 

[biffvernon]

But this particular pressure vessel is no longer a pressure vessel. It's more like a sieve.

mscharisma's point is valid. Going over 100 produces a lot of steam.

 

[Bandit127]

But this particular pressure vessel is no longer a pressure vessel. It's more like a sieve.

mscharisma's point is valid. Going over 100 produces a lot of steam.

This is Unit 5 - I have not seen anything yet to suggest that the RPV is leaking pressure.

To be fair, I cannot find any data that states what the pressure is in the Unit 5 RPV either.

If it is still a "pressure vessel", then if steam starts to be formed then the pressure will rise and the system will self limit and not boil up.

 

[biffvernon]

Ah, right,#5. my bad. Apologies.

 

[mscharisma]

You are missing pressure. Water boils at 100°C only at atomspheric pressure.

It boils at about 75°C on top of Everest and 0°C in a vacuum.

The opposite is also true, as pressure increases so the boiling point increases. To understand the relationship between boiling point and pressure, have a look at a steam table.
http://www.simetric.co.uk/si_steam.htm

This means that (for instance) water at 2 bar (i.e. atmospheric pressure x 2) boils at 120.42°C.

So, if the pressure vessel is (for instance) at 2 bar, 94°C is still quite a way from boiling.

Thank you (and others) for helping me understand this better. I suppose, it struck me as odd that TEPCO decided not to use the emergency water injection system and to rather not "work in the dark." Given that they have about a million things going wrong everywhere else, it seemed overly nonchalant to me to not proceed with the utmost caution.

 

[MadderDoc]

<..>
I don't actually know why they want to switch away from fire line, I asked about this recently on this thread but nobody responded.

Perhaps everybody here also do not know, certainly I do not :-) Could it be -- I speculate -- that using the normal feed water line (to which they appear to be switching) can be expected to become a more practical/convenient way to inject water to the rpv in the long term, considering there is, afaik, a plan to recycle some of the leaked water through pumping into the condensers of the turbine buildings?

 

[mscharisma]

This is Unit 5 - I have not seen anything yet to suggest that the RPV is leaking pressure.

To be fair, I cannot find any data that states what the pressure is in the Unit 5 RPV either.

If it is still a "pressure vessel", then if steam starts to be formed then the pressure will rise and the system will self limit and not boil up.

Here is pressure data for unit 5 on page 8: http://www.nisa.meti.go.jp/english/files/en20110529-2-2.pdf
Unless I'm still not getting this right, 0.108MPa is around atmospheric pressure, no?

 

[~kujala~]

I don't actually know why they want to switch away from fire line, I asked about this recently on this thread but nobody responded.

I think they can pump more water into the reactor using the feedwater line than the fire line. It might be something to do with the technical differencies between the two lines.
Although they are not using max capacity now they probably want to have some reserve if the temperatures starts suddenly raising.
Another option is that they are testing the feedwater lines now because at some point they have to switch to a closed circuit. Was it the feedwater line they are going to use or some other line?

Something to note also: For units #1 and #2 in the latest IAEA report stands:
"The need for boric acid injection is investigated be TEPCO"
http://www.slideshare.net/iaea/tabl...shima-daiichi-nuclear-power-plant-18-may-2011
http://www.slideshare.net/iaea/tabl...shima-daiichi-nuclear-power-plant-18-may-2011

Unit #3 and #4 summaries:
http://www.slideshare.net/iaea/tabl...shima-daiichi-nuclear-power-plant-18-may-2011
http://www.slideshare.net/iaea/tabl...shima-daiichi-nuclear-power-plant-18-may-2011

When was it last time they injected boric acid to #1 and #2?

 

[turi]

Here is pressure data for unit 5 on page 8: http://www.nisa.meti.go.jp/english/files/en20110529-2-2.pdf
Unless I'm still not getting this right, 0.108MPa is around atmospheric pressure, no?

Yes, that's about atmospheric pressure. Before cold shutdown pressure was above atmospheric pressure, e.g. at March 20th pressure was 1296 MPa. http://www.nisa.meti.go.jp/english/files/en20110320-3.pdf

 

[elektrownik]

Yes, that's about atmospheric pressure. Before cold shutdown pressure was above atmospheric pressure, e.g. at March 20th pressure was 1296 MPa. http://www.nisa.meti.go.jp/english/files/en20110320-3.pdf

so it was boiling after pump failed ? it was 94C...

 

[turi]

so it was boiling when pump failed ? it was 94C...

Um, no. Sorry, I don't know what exactly you mean. At 94 °C there would have to be underpressure to make water boiling.

 

[mscharisma]

Um, no. Sorry, I don't know what exactly you mean. At 94 °C there would have to be underpressure to make water boiling.

Whether boiling or near boiling, I just don't understand why they would let it get that close, given that they had an emergency system in place they could have used?

"The temperature of the core and the fuel pool had reached 93.6 degrees and 46 degrees, respectively, by noon Sunday compared with 68 degrees and 41 degrees at 9 p.m. Saturday.

The backup pump kicked in at 12:31 p.m. Sunday, and the temperature of the core had been brought down to 83 degrees by 1 p.m., a Tepco spokeswoman said by phone later Sunday."

Edit: Kyodo is reporting on this unit 5 incident also, sounding more alarming than the Japan Times did.
http://english.kyodonews.jp/news/2011/05/94090.html

 

[PietKuip]

This ought to keep us busy for a few hours:

http://dels.nas.edu/resources/static-assets/nrsb/miscellaneous/SekimuraPresentation.pdf

Something I noticed about the earthquale accelerations on page 13: those at unit 4 are smaller than the other units. As a seismological layperson, I find such large difference very surprising, and I do not know what this means. Is unit 4 more loosely connected to the ground? Are lower values good, or does it indicate possible trouble?

(Assuming this is not caused by instrument error, transcription error, or all the other problems with Tepco data.)

 

[DSamsom]

Radioactive release into the ocean increases again. Probably due to the difficulties of dealing with the amount of radioactive water. And this was before the heavy rain:

http://www3.nhk.or.jp/daily/english/30_01.html