Japan Earthquake: Nuclear Plants at Fukushima Daiichi

In summary: RCIC consists of a series of pumps, valves, and manifolds that allow coolant to be circulated around the reactor pressure vessel in the event of a loss of the main feedwater supply.In summary, the earthquake and tsunami may have caused a loss of coolant at the Fukushima Daiichi NPP, which could lead to a meltdown. The system for cooling the reactor core is designed to kick in in the event of a loss of feedwater, and fortunately this appears not to have happened yet.
  • #12,426
etudiant said:
Afaik, there is no gas management system in place other than at reactor 1.

Not sure why you say that, unless we are talking about different sorts of gas management systems. Reactor 2 has had one for months now (thats where the gas sample analysis is coming from for that reactor, Xe133 etc) and reactor 3's started operation on Feb 23rd.

I haven't spent ages studying the video footage but isn't the area in question between reactors 2 & 3, not 3 & 4?

Looking at Tepco status updates covering Feb 28th, there is one operation that could be relevant:

From 8:51 am to 3:45 pm on February 28, according to the investigation on trenches on January 19, 2012, high density contaminated water inside was found inside circulating water pump discharge valve pit of Unit 3 water pump room. Therefore, we started to transfer the accumulated water from the pit to the basement of Unit 2 Turbine Building.
 
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  • #12,427
Anybody got any comments on the radiation readings, photos or videos of the recent robot activity inside reactor 2 building (mostly 5th floor)?

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120228_04-e.pdf

http://www.tepco.co.jp/en/news/110311/index-e.html

I haven't looked at the videos yet but it was good to see an image of the area above the reactor well, not obscured by barriers this time as they gave the new robot a longer camera arm.
 
  • #12,428
SteveElbows said:
Not sure why you say that, unless we are talking about different sorts of gas management systems. Reactor 2 has had one for months now (thats where the gas sample analysis is coming from for that reactor, Xe133 etc) and reactor 3's started operation on Feb 23rd.

I haven't spent ages studying the video footage but isn't the area in question between reactors 2 & 3, not 3 & 4?

Looking at Tepco status updates covering Feb 28th, there is one operation that could be relevant:

From 8:51 am to 3:45 pm on February 28, according to the investigation on trenches on January 19, 2012, high density contaminated water inside was found inside circulating water pump discharge valve pit of Unit 3 water pump room. Therefore, we started to transfer the accumulated water from the pit to the basement of Unit 2 Turbine Building.

Thank you, the suggestion seems a plausible explanation.
Re gas management, my mistake. I was thinking of the emissions management, which is a different aspect.
Gas management has indeed been ongoing for months at reactors 1 and 2.
 
  • #12,429
Well this is odd.
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_01.jpg
a large number of pairs of rubber boots are ranged neatly near what seems to be the concrete cap of the reactor well (unit 2). The picture was taken with a robot.
another odd detail in
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_02.jpg
there are bits of what seems to be the SFP guardrail (the remains of bottom panels, to be precise) which seem melted and burnt.
there seems to be some discoloration/soot here as well:
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_03.jpg
 
  • #12,430
That might be smoke/steam from an internal combustion engine.

I would assume they would eventually repair and start some of the generators or other engine run equipment on the facility with the first start billowing much white smoke.

Just a guess.
 
  • #12,431
I haven't spent ages studying the video footage but isn't the area in question between reactors 2 & 3, not 3 & 4?
Indeed, my mistake.
 
  • #12,432
http://youtu.be/fimRJocH_90

This video talks about cracks in the soil at the plant. Which started after earthquakes. Has there been an earthquake near there of late?
 
  • #12,433
zapperzero said:
Well this is odd.
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_01.jpg
a large number of pairs of rubber boots are ranged neatly near what seems to be the concrete cap of the reactor well (unit 2). The picture was taken with a robot.
another odd detail in
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_02.jpg
there are bits of what seems to be the SFP guardrail (the remains of bottom panels, to be precise) which seem melted and burnt.
there seems to be some discoloration/soot here as well:
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_03.jpg

Plus some kind of photoshopping ... http://www.gen4.fr/blog/ [Broken] (french)
 
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  • #12,434
zapperzero said:
Well this is odd.
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_01.jpg
a large number of pairs of rubber boots are ranged neatly near what seems to be the concrete cap of the reactor well (unit 2). The picture was taken with a robot.
another odd detail in
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_02.jpg
there are bits of what seems to be the SFP guardrail (the remains of bottom panels, to be precise) which seem melted and burnt.
there seems to be some discoloration/soot here as well:
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_03.jpg

From the curvature of the panels in PIC 2 as well as from the position of the FHM in PIC 1 (present in PIC 2 on the right) I'd say those guardrail panels are the top of reactor guard panels (also visible from the other side in PIC 1)
 
  • #12,435
denislaurent said:
Plus some kind of photoshopping ... http://www.gen4.fr/blog/ [Broken] (french)

I'm intrigued, that sure is some shoddy work with the clone stamp! And the comparison with the low-res video-cap from the same spot proves that it is not an honest stitching artifact but rather a shoddy attempt at removing something from the hi-res image.
 
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  • #12,436
zapperzero said:
Well this is odd.
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_01.jpg
a large number of pairs of rubber boots are ranged neatly near what seems to be the concrete cap of the reactor well (unit 2). The picture was taken with a robot.
And the trash bags lying around... looks like a messie's home.
A German bakery would be closed if regulators found such a mess at the workplace.

Edit: Look at the end of the rail in the lower left of the image. Looks somehow unusual, rail transiting into concrete seamlessly, making me think of photoshop.
Edit2: Thanks denislaurent for the link, there is even more of strange details that I find somehow suspicious.
zapperzero said:
another odd detail in
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_02.jpg
there are bits of what seems to be the SFP guardrail (the remains of bottom panels, to be precise) which seem melted and burnt.
The concrete (dis)coloration indicates that condensation happens here up to saturation.
To me the crane rails seem thoroughly rusted. I think they will have completely crumbled in a few years if nothing protective is done, making the recovery of the spent fuel using the old crane impossible.
IMO Tepco should grease them with water displacer asap to avoid complicarions like this.
zapperzero said:
there seems to be some discoloration/soot here as well:
http://www.tepco.co.jp/tepconews/pressroom/110311/images/120228_03.jpg

I am not sure if soot.
High humidity and discolorations concentrating in lower parts, where main condensation occurs.
Black fungus thrives in the Chernobyl sarcophagus in extremely radioactive areas, why should this be different in Fukushima?
Looking closely, mostly organic surfaces (plastics and paint) seem discolored, and these are preferred by fungi.
 
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  • #12,437
denislaurent said:
Plus some kind of photoshopping ... http://www.gen4.fr/blog/ [Broken] (french)
If you look at the video (3:08), you can see that some kind of error occurred while taking the picture (look at the screenshots I attached).
The idea of photoshopping a picture they are not mandated to release in the first place sounds weird to me, especially when the "hidden" area seems to only contain a piece of paint that fell off from somewhere.
 

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  • #12,438
Atomfritz said:
And the trash bags lying around... looks like a messie's home.
Oh, come on! This is a building that was subjected to a powerful earthquake,
then a mil-level explosion!
I think they will have completely crumbled in a few years if nothing protective is done, making the recovery of the spent fuel using the old crane impossible.
IMO Tepco should grease them with water displacer asap to avoid complicarions like this.
Any use of the main crane or the FHM is pretty much out of the question.
If the earthquake didn't damage the support rails, the explosion would have.
Unless the rails were tested very thoroughly and re-surveyed by millwrights, the
crane could fall off the rails the first time it was moved, adding major complications
to any recovery. Massive corrosion is probably going to be a problem in the
disassembly of the plant, though, you are right. The Quince displays show
9 C and ~75% RH, which is a bad situation.

Jon
 
  • #12,439
Atomfritz said:
Looking closely, mostly organic surfaces (plastics and paint) seem discolored, and these are preferred by fungi.

The panel closest to the camera seems to be missing altogether - which is why I thought fire in the first place.
 
  • #12,440
jmelson said:
Oh, come on! This is a building that was subjected to a powerful earthquake,
then a mil-level explosion!
Jon

Excuse me, what explosion would that be? Afaik, there was a blast somewhere in the vicinity of the torus (5 levels down) and the concrete plug of the reactor well seems to be in its place so I don't think the torus breach could have very much bearing on whatever happened to those panels.

Also, this deck is supposed to have remained untouched by humans ever since the accident. I do not understand the boots, but if they are there since the earthquake, well... why would other stuff be strewn about willy-nilly? Remember that unit 2 is the one with the roof still intact.
 
  • #12,441
zapperzero said:
Excuse me, what explosion would that be?
There was no explosion, true: however judged by the survey map of the level there was something coming up around the concrete plug of the reactor, and I think it's safe to assume that it wasn't cold nor careful.

Boots and the pink plastic bags/sheets: as I remember to the pre-accident tour pictures such things are often used during any activities on the top floor - for example for a refueling operation practically the whole site is wrapped up. We don't have any information about what was in progress right before the accident happened.
 
  • #12,442
Jim Lagerfeld said:
I'm intrigued, that sure is some shoddy work with the clone stamp! And the comparison with the low-res video-cap from the same spot proves that it is not an honest stitching artifact but rather a shoddy attempt at removing something from the hi-res image.

As they have released also the unedited video, I doubt there is a big conspiracy plan behind. What I'd bet had happened, is the PR guy/webmaster/poor young engineer responsible for drafting press releases and hand-outs, was told to get 3-4 shots out of the video, clean them up as best as he could and make a pdf out of it. If you notice, exposure, light, color also change in the pictures, that are brighter and more detailed than the video (video is so dark that it's even difficult to spot the boots). Trying to clean up the pictures, he probably overdid here and there
 
  • #12,443
Regarding the strange image distorting/tile duplication which makes the impression of image editing:

I have looked at the video and the image closely trying to find out what could be the reason for this.

Just to save typing I copied my comment on Ex-SKF here:
Now downloaded the video and looked at it closely.
Around 3:10 plus/minus a few seconds there can be taken some more observations.

As Yosaku correctly notes, the image is parted up into 16 tiles, apparently transmitted sequentially, strangely of unequal size (would really like to know the technical reason why the tiles aren't equal-sized).

The image "blacks out" when the radiation counter jumped to about 0.2 sieverts (in 1 meter height? probably then higher near at floor level where the electronics are probably located).

The operator then hastily moved back Quince. I suppose it was a quick reaction to protect Quince 2 from crashing/latching-up because of radiation.

However, what appears strange to me is the discrepancy of the image shown in the video and the high-res image.
But there could be several benign technical explanations for this.
The display on the Quince control panel (showed in the video) is probably a zoomed-down version of the native resolution of the camera image.

But then the question comes up: how came the seamless impression of the duplicate tile which makes the impression of image editing?
If the tile was a simple duplicate as Yosaku assumes, it would be easily recognizable, like a copied-pasted part of the image.

It is probably not that simple.
When you look very carefully at the hires image you get the impression that the lower left tile actually could be sort of averaging overlaying of two tiles.
Technically this could be caused by a line decoder malfunction caused by radiation, leading to two lines being read out simultaneously, mixing/averaging the output.

So I have to retract my suspicion of image editing, as there seems to be nothing of particular importance in the lower-left image tile.

However, one thing can possibly be concluded of this: Quince's electronics radiation resistance probably is around 0.2 sieverts (assuming the radiation counter is located near the electronics)
I fear Tepco has to be very careful to avoid Quince 2 to die soon too.

Any thoughts/comments about this?
 
  • #12,444
Atomfritz said:
Any thoughts/comments about this?
IIRC those robots were surveyed much nastier places there, so I don't think that they have so limited radiation resistance.

About the tiles: as far as I know it's a common practice that the operator gets a live video feed with limited resolution only to conserve bandwidth, and he can ask for full resolution still images if necessary. (Maybe this is the explanation of the luminance difference between the video and the picture used for the pdf document.)

The live feed has twenty-some frames per second, it's pretty resistant against any coding- or transmission errors while the still images are more sensitive. Maybe that's all.
 
  • #12,445
From what I recall reading, the Quince robots can operate in up to 2Sv worth of radiation reliably, I don't think the 0.2Sv measurement could have caused any problems.

I will say I question their choice of the camera lens, it makes for some quite distorted images, maybe it has something to do with radiation resistance?
 
  • #12,446
Rive said:
There was no explosion, true: however judged by the survey map of the level there was something coming up around the concrete plug of the reactor, and I think it's safe to assume that it wasn't cold nor careful.

The rather unsteady footage from last September, taken from the opening in the wall of reactor 2, does show stuff rising from that area.

http://tepco.webcdn.stream.ne.jp/www11/tepco/download/110924_01j.zip

As for the boots, we don't know if they were trying to deal with something such as sloshing of water from the reactor 2 spent fuel pool immediately after the earthquake but before the situation got too serious for people to be inside the building.
 
  • #12,447
http://www3.nhk.or.jp/news/genpatsu-fukushima/20120302/index.html The inside of the offsite center was shown to the press for the first time since the accident. They saw the large screen supposed to show each reactor's realtime data or predictions of the spreading of radiations, which did not function at all. The phone system supposed to reach each local government's person in charge by pushing a button also did not function because of the blackout. The offsite center had no air filtering system, and the radiation eventually rose to 200 μSv/hour so it had to be evacuated. The Nuclear Safety Commission has a plan to divide offsite centers into two parts. One part would be far enough from the plant, and the other part, in charge of evacuations would be close to the plant. But the final decision has not been taken yet.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120302/1400_ondokei.html On 1 March in the night, Tepco submitted its report to NISA about unit 2's alternative temperature measurements. Thermometers will be inserted through the pipes that connect to the reactor inside. It will be necessary to lower the radiations in the working environment, and in order to solve many still unsolved problems, it might be necessary to design new tools and techniques suitable for working in narrow spaces. If all the conditions are met, the measurements won't start before the end of July. Tepco is also exploring indirect methods, such as analysing the temperature of the water flowing out of the reactor.

http://www.tepco.co.jp/cc/press/betu12_j/images/120302a.pdf The report to NISA : "Correspondence for temperature increase in the lower part of the Reactor Pressure Vessel of Unit 2 at TEPCO Fukushima Daiichi Nuclear Power Station" (Japanese).
 
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  • #12,448
The 1 March report ( http://www.tepco.co.jp/cc/press/betu12_j/images/120302a.pdf ) is divided into two parts. The first half, down to page 43 is about the plan to install alternative measurement tools. The second half from page 44 to the end is the assessment of existing thermometers.

On pages 88/91 - 89/91 we find a table with the resistance values of each thermometer in unit 2. For example here are the values for TE-2-3-69H2 (Vessel wall above bottom head) :

Regular inspection value : 300.47 Ω
2011.9.29 151.71Ω 0.50
2011.12.1 153.20Ω 0.51 1.01
2011.12.12 151.80Ω 0.51 1.00
2012.1.27 151.06Ω 0.50 1.00
2012.2.13 155.32Ω 0.52 1.03
2012.2.23 173.36Ω 0.58 1.15
2012.2.23 173.10Ω 0.58 1.15
2012.2.24 175.13Ω 0.58 1.16
2012.2.24 175.23Ω 0.58 1.16
2012.2.25 174.02Ω 0.58 1.15
2012.2.26 174.13Ω 0.58 1.15
2012.2.27 173.45Ω 0.58 1.15
2012.2.28 174.74Ω 0.58 1.16
2012.2.29 173.57Ω 0.58 1.15

The rates written after each Ω value (1) are : (2) measured value/regular inspection value ; (3) measured value/lowest measured value. "1.15" means that the resistance rose by 15% between 29 September and 29 February.

A plot with TE-2-3-69H2 resistance (pink) and temperature (blue) values is available page 63/91.

Here is the footnote with the meaning of each symbol in the first column of the table pages 88/91 - 89/91 :

〇 : not assessed as being broken
A1 : not connected to the central control room with a cable (backup sensor. the high radiation in reactor building basement prevents access)
A2 : assessed as being broken during the regular inspections [prior the accident]
B1 : already reported as being broken in the mid term safety report
B2 : newly assessed as being broken (wire cut)
When the measured value is unstable inside a range we wrote down the highest value.
 
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  • #12,449
has unit 3 top floor been covered with something?
 
  • #12,450
tsutsuji said:
The 1 March report ( http://www.tepco.co.jp/cc/press/betu12_j/images/120302a.pdf ) is divided into two parts. The first half, down to page 43 is about the plan to install alternative measurement tools. The second half from page 44 to the end is the assessment of existing thermometers.

I translate the last part of the 1 March report's first part, on http://www.tepco.co.jp/cc/press/betu12_j/images/120302a.pdf pages 8 and 9 (what follows is attachments) :

(3) working plan for alternative thermometer equipments

a. Selection of alternative thermometer equipments and sending devices


After making comparative studies of the thermometers that are to be inserted into the pipes connecting to the RPV, and of the devices to perform such insertion, from the perspective of resistance to radiations or maximum temperature, we selected two kinds of metal sheath thermocouples and two kinds of sending devices and industrial endoscopes.

« metal sheath thermocouples »

* A company's metal sheath thermocouple : φ1.0mm×150m (maximum temperature 650°C)
* B company's metal sheath thermocouple : φ0.5mm×300m (maximum temperature 650°C)

« sending devices »

* wiring equipment : φ4.5mm×30m (inserted by hand)
* industrial endoscope : φ4.0mm×30m (inserted by hand. The bending wire on the extremity can be [remote] controlled)

(attachments 5 [page 38/91], 6 [page 39/91])

b. The work's implementation plan and problems

At present, the alternative means having the highest probability of implementation is the one inserting a thermometer inside the jet pump instrumentation line. Based on this, we selected a detailed working procedure and extracted the relevant engineering and feasability problems. Many problems cannot be settled unless a field study is performed, but if at least the following problems are not solved, it will be difficult to perform the work:

« Problems »

* Being able to lower the radiation in the work area to 15 mSv/hour or below
* In order that the RPV gasses do not flow out from the instrumentation pipe that is being cut, we plan to use an engineering method where the pipe inside is frozen (filling it with water) while cutting, but as the distance between the PCV penetration end plate and the closing valve is short (300 mm or less), the working space is narrow. Working must be possible in such a narrow space.

A survey will be performed to find detailed radiation data in the working location. After this, we will plan decontamination and shielding, and the results will be checked on location. Also, we plan to diminish the work risks by testing the frozen cutting method on a mock-up and to develop tools to enable working in a narrow space. Please note that the problems encountered if we use the routes selected as priority level 2 (through the water level gauge line, liquid control system (SLC) differential pressure detector line, or the Traversing Incore Probe (TIP)), will be nearly the same as if we use the jet pump instrumentation line, so we wrote here the detailed plans for the jet pump instrumentation line work as a representative case.

(attachment 7 [page 40/91 - 42/91])

c. Working schedule

The earliest start of work is at the beginning of July, bringing the completion of work at the end of July. The following schedule is based on the prerequisite that the working environment's radiation is lowered to a level where working is possible, that new technologies do not need to be developped (application of existing technologies), and that the conclusions drawn from the mock-up test's results do not require more than simple modifications.

The completion of tasks that have major consequences on the schedule are noted below as "hold points" (HP). We shall pay attention to the completion of each hold point, and in case the conditions are changed, we shall quickly change the plan, and head toward the installation of alternative thermometers within the shortest time as possible. Please note that there is a high probability of performing the priority level 2 works (through SLC, or TIP), so that, if possible, the field studies about those will be performed at the same time as the one for the priority 1 work (through jet pump instrumentation line).

HP1 : field study 1 (checking the working area's radiation and space) : mid March
HP2 : study of engineering method (assess if it is possible using existing technology) : mid April
HP3 : confirm an effective decrease of radiations after decontamination and shiedling : end of May
HP4 : end of the mock-up : beginning of July

(attachment 8 [page 43/91])
 
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  • #12,451
RoseHeart said:
TEPCO...what a bunch of techno spew..
Why ..oh...why I wonder does..it look like this?


The reactors are still generating close to a megawatt each of decay heat.
That heat has to go somewhere. Some of it boils water, probably because the cooling flow is pretty uneven inside the reactors. That gives steam, which still carries a noticeable amount of contamination.
However, compared to a year ago, the emissions now are minuscule. The damage is done, it just will be a very long cleanup.
 
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  • #12,452
I was wondering if anyone here had any thoughts/special insights on the water situation at the plant.

As I understand it, currently TEPCO is decontaminating the water they are using for cyclic cooling for Cesium only. There is apparently a multi-nuclide decontamination system in the works that will remove 40 or more nuclides, and potentially allow the decontaminated water to be even more safely discharged into the ocean. (Whether they get public understanding or approval to do this is another matter).

I also understand that about 300-500 tonnes of water leaks into the damaged reactor basements per week from groundwater run-off, and that TEPCO has stated the flow rates of groundwater into the basements depends on how quickly they pump water out of the basements, which is why they have decided to keep water levels in the basements at around 3,000 OP.

If you track TEPCO's stored water reports, you notice that the water levels in the basements have changed little, while the decontaminated water volumes continue to climb. Suggesting TEPCO is decontaminating just enough water to cool the plants and remove the groundwater run-off, but not actually trying to drain the basements.

But what is the ultimate end game? For starters, why decontaminate the water at all before using it cool the plant. Wouldn't it be simpler to pump the contaminated water in a shorter cycle into the reactors for cooling? Decontaminated water could then be stored separately for eventual discharge without pumping it back through the plant and contaminating again.

What am I failing to see here?

M.
 
  • #12,453
mloub said:
I was wondering if anyone here had any thoughts/special insights on the water situation at the plant.

But what is the ultimate end game? For starters, why decontaminate the water at all before using it cool the plant. Wouldn't it be simpler to pump the contaminated water in a shorter cycle into the reactors for cooling? Decontaminated water could then be stored separately for eventual discharge without pumping it back through the plant and contaminating again.

What am I failing to see here?

M.

Presumably TEPCO is trying to reduce the ambient radioactivity levels in anticipation of future clean up efforts.
I've seen some claims that the water in the plant now is at a millionth of the initial contamination level, but no official data, even though that would be very helpful.
Perhaps some of the more savvy members of this forum could give guidance.
 
  • #12,455
  • #12,457
mloub said:
But what is the ultimate end game? For starters, why decontaminate the water at all before using it cool the plant. Wouldn't it be simpler to pump the contaminated water in a shorter cycle into the reactors for cooling? Decontaminated water could then be stored separately for eventual discharge without pumping it back through the plant and contaminating again.

What am I failing to see here?

M.

Your question is pretty similar to the one I asked on 16 December :

tsutsuji said:
Why do they need that big Areva/Kurion/Sarry water purification facility in the first place ? I understand that they need to remove salt because salt and steel do not get on very well with each other. But why remove cesium ?

What I was missing was that pouring radioactive water into the reactors would create other clouds of radioactive steam over the plant and over Japan. So it is better to pour clean water. See Astronuc and Rmattila's answers at https://www.physicsforums.com/showthread.php?p=3671515&highlight=line#post3671515

And about how to prevent ground water from flowing in :

Astronuc said:
Pretty much the only way to do that is to have wells outside of the containment that draw out the ground water.

I think this is what Tepco is trying to do, as reported in the last monthly mid-long term meeting :

tsutsuji said:
http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/m120227_05-j.pdf
* Page 37/94 to 46/94 : subdrain decontamination tests
Ahead of the restart of the subdrain system, it is necessary do decontaminate the water inside the subdrain pits, so we are performing the "decontamination tests" and the "water drawing up tests".

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/m120227_05-j.pdf page 39/94 (my translation)
 
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  • #12,458
Why remove cesium?

It could have something to do with the plant being on the shore of a salt water body that could very well transport dissolved salts worldwide.
 
  • #12,459
http://www.yomiuri.co.jp/science/news/20120303-OYT1T00609.htm [Broken] Another unit 2 thermometer is having abnormal values and is removed from the list of thermometers used for reactor surveillance.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120303_03-e.pdf Top of junction of skirt supporting RPV(270°) (TE-2-3-69F3)resistance rose to 1.76 times the September value.
 
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  • #12,460
etudiant said:
The reactors are still generating close to a megawatt each of decay heat.

Are you sure about the 1MW? They're keeping the reactors cool with 6 or 9 t/hour of water, I don't believe that would be enough if the core was still emitting that much energy...
 
<h2>1. What caused the Japan earthquake and subsequent nuclear disaster at Fukushima Daiichi?</h2><p>The Japan earthquake, also known as the Great East Japan Earthquake, was caused by a massive underwater earthquake that occurred on March 11, 2011. The earthquake had a magnitude of 9.0 and was the strongest ever recorded in Japan. The earthquake triggered a massive tsunami, which caused extensive damage to the Fukushima Daiichi nuclear power plant and led to a nuclear disaster.</p><h2>2. What is the current status of the nuclear reactors at Fukushima Daiichi?</h2><p>As of now, all of the nuclear reactors at Fukushima Daiichi have been shut down and are no longer in operation. However, the site is still being monitored for radiation levels and there is an ongoing effort to clean up the radioactive materials that were released during the disaster.</p><h2>3. How much radiation was released during the Fukushima Daiichi nuclear disaster?</h2><p>According to the International Atomic Energy Agency, the Fukushima Daiichi nuclear disaster released an estimated 10-15% of the radiation that was released during the Chernobyl disaster in 1986. However, the exact amount of radiation released is still being studied and debated.</p><h2>4. What were the health effects of the Fukushima Daiichi nuclear disaster?</h2><p>The health effects of the Fukushima Daiichi nuclear disaster are still being studied and monitored. The most immediate health impact was the evacuation of approximately 160,000 people from the surrounding areas to avoid exposure to radiation. There have also been reported cases of thyroid cancer and other health issues among those who were exposed to the radiation.</p><h2>5. What measures have been taken to prevent future nuclear disasters in Japan?</h2><p>Following the Fukushima Daiichi nuclear disaster, the Japanese government has implemented stricter safety regulations for nuclear power plants and has conducted stress tests on all existing plants. They have also established a new regulatory agency, the Nuclear Regulation Authority, to oversee the safety of nuclear power plants. Additionally, renewable energy sources are being promoted as a more sustainable and safer alternative to nuclear power in Japan.</p>

1. What caused the Japan earthquake and subsequent nuclear disaster at Fukushima Daiichi?

The Japan earthquake, also known as the Great East Japan Earthquake, was caused by a massive underwater earthquake that occurred on March 11, 2011. The earthquake had a magnitude of 9.0 and was the strongest ever recorded in Japan. The earthquake triggered a massive tsunami, which caused extensive damage to the Fukushima Daiichi nuclear power plant and led to a nuclear disaster.

2. What is the current status of the nuclear reactors at Fukushima Daiichi?

As of now, all of the nuclear reactors at Fukushima Daiichi have been shut down and are no longer in operation. However, the site is still being monitored for radiation levels and there is an ongoing effort to clean up the radioactive materials that were released during the disaster.

3. How much radiation was released during the Fukushima Daiichi nuclear disaster?

According to the International Atomic Energy Agency, the Fukushima Daiichi nuclear disaster released an estimated 10-15% of the radiation that was released during the Chernobyl disaster in 1986. However, the exact amount of radiation released is still being studied and debated.

4. What were the health effects of the Fukushima Daiichi nuclear disaster?

The health effects of the Fukushima Daiichi nuclear disaster are still being studied and monitored. The most immediate health impact was the evacuation of approximately 160,000 people from the surrounding areas to avoid exposure to radiation. There have also been reported cases of thyroid cancer and other health issues among those who were exposed to the radiation.

5. What measures have been taken to prevent future nuclear disasters in Japan?

Following the Fukushima Daiichi nuclear disaster, the Japanese government has implemented stricter safety regulations for nuclear power plants and has conducted stress tests on all existing plants. They have also established a new regulatory agency, the Nuclear Regulation Authority, to oversee the safety of nuclear power plants. Additionally, renewable energy sources are being promoted as a more sustainable and safer alternative to nuclear power in Japan.

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