What happened at Fukushima Daiichi during the Japan earthquake?

[MadderDoc]

I updated the tables concerning Cs activities of the water at the treatment facilities. The activities seem to have dropped by about a decade in 9 months.

That is a quite impressive reduction. Have you done some thought as to where all that radioactivity has gone? Last time I read something about the status, as I recall, they had treated about 135000 cubic meters of contaminated water.

 

[MadderDoc]

The white stuff may be the salt left behind by the many thousands of gallons of seawater that were sprayed willy nilly about the place.

I suppose it could be salt. Also it might be an effect of general soluble mineral transport by incoming rainwater; the cracked wall section is facing west and the ceiling above it has been blown away, so it is actually quite exposed to the weather.

 

[Tepconium-311]

I also don't understand this TIP room story.

First they say the door is closed, then they suddenly discover that it is blown away. How come?

Tepco is innocent.
The whole thing is haunted.
Even containment equipment hatch doors swing open and close at will.

I suppose it could be salt. Also it might be an effect of general soluble mineral transport by incoming rainwater; the cracked wall section is facing west and the ceiling above it has been blown away, so it is actually quite exposed to the weather.

Sands used for construction is usually washed in water before usage to avoid soluble and organic contents.
So it is cement salts and/or seawater salts.
Quantity indicates deep concrete cracks.

 

[Rive]

Yeah, right. And they downsampled the photo such as to not confuse people with minor details. Saltwater in my eyes.

Speaking of details, what would be the nature of the white stains running down that part of the wall below the crack above them in the photo from the 2012 announcement? There are no stains visible in the 2011 photo of the same spot:[/PLAIN]

There are stains on the 2011 photo:
https://www.physicsforums.com/attachment.php?attachmentid=48104&stc=1&d=1339053367

I think it's not salt. As I know the top level of U4 were not 'sprayed': even the first attempts to fill the pool were more or less accurate (with the concrete pump).

What about mud/dust (carried by rainwater)?

Check the pipe in the right-bottom corner:
http://cryptome.org/2012-info/daiichi-12-0526/pict6.jpg

Top of the equipment racks on the right:
http://cryptome.org/2012-info/daiichi-12-0526/pict8.jpg

Top of the machinery (2TON) on the right:
http://cryptome.org/2012-info/daiichi-12-0526/pict7.jpg

COncrete walkway on the right:
http://cryptome.org/2012-info/daiichi-12-0526/pict16.jpg

 

[rmattila]

That is a quite impressive reduction. Have you done some thought as to where all that radioactivity has gone? Last time I read something about the status, as I recall, they had treated about 135000 cubic meters of contaminated water.

In Dec 13., it was stated that 189 610 tons would have been treated (http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e_2.pdf , page 12). Assuming a constant rate of 500 tons per day since then, the current amount would be around 280 000 t.

If the average Cs-137 concentration would have been around 1e5 Bq/cm3, the filters would now contain some 140 PBq of Cs-137, i.e. about 15 - 25 % of the entire initial inventory of cores 1-3.

 

[SteveElbows]

I've posted a few of the air photos that have been published from end of May, also there is this live footage produced from the Asahi Shimbun helicopter..

Thanks, will check it out.

And so many thanks to Tsutsuji for the brilliant document translations, highly appreciated.

Now then, I guess they must have gained entry to reactor 3 torus room because this document which shows their effort to measure water levels of these areas in reactors 2 & 3 has some photos from 3:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120607_02-e.pdf

 

[turi]

[...]
Now then, I guess they must have gained entry to reactor 3 torus room because this document which shows their effort to measure water levels of these areas in reactors 2 & 3 has some photos from 3:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120607_02-e.pdf

Interesting times. A year ago I wouldn't have expected to see people entering the torus rooms of units 2 and 3 by now.

 

[tsutsuji]

http://jiji.com/jc/c?g=soc_30&k=2012060700959 unit 2 & 3 torus rooms were inspected on 6 June. No damage or deformation found. They have not found the leakage points either.

http://www.47news.jp/CN/201206/CN2012060701002039.html accumulated water depth in unit 2: 5.3 m ; unit 3: 5.4 m.

 

[zapperzero]

http://www.47news.jp/CN/201206/CN2012060701002039.html accumulated water depth in unit 2: 5.3 m ; unit 3: 5.4 m.

I wonder if it's a coincidence (probably not). One could maybe look at existing penetrations which are near that level, for likely candidates. In any case, the water looks much cleaner than before.

 

[MadderDoc]

<..> I guess they must have gained entry to reactor 3 torus room because this document which shows their effort to measure water levels of these areas in reactors 2 & 3 has some photos from 3:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120607_02-e.pdf

Yes indeed, some of the water level measuring positions would seem to imply that a person must enter the torus room, at least ever so slightly. http://photo.tepco.co.jp/en/date/2012/201206-e/120607_02e.html appear to have been taken by a robot of the same type that showed us the Unit 2 catwalk. The amount of stray gamma captured by the CCD inside the torus room of Unit 3 seems pretty high.

 

[MadderDoc]

In Dec 13., it was stated that 189 610 tons would have been treated (http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e_2.pdf , page 12). Assuming a constant rate of 500 tons per day since then, the current amount would be around 280 000 t.

If the average Cs-137 concentration would have been around 1e5 Bq/cm3, the filters would now contain some 140 PBq of Cs-137, i.e. about 15 - 25 % of the entire initial inventory of cores 1-3.

Interesting to see from your spreadsheet that a large proportion of it seems to have been taken out of circulation within just the first couple of months.

I dug around and found the latest report to NISA on the accumulated water:
http://www.tepco.co.jp/en/press/corp-com/release/betu12_e/images/120530e0201.pdf
It says that by the end of May 2012, a cumulative total of 340 000 tons has been treated.

 

[MadderDoc]

There are stains on the 2011 photo:
https://www.physicsforums.com/attachment.php?attachmentid=48104&stc=1&d=1339053367

Yes, but I'd say, they are not as pronounced and in as many paths. This may have been a progressively developing thing.

I think it's not salt. As I know the top level of U4 were not 'sprayed': even the first attempts to fill the pool were more or less accurate (with the concrete pump).

I also lean to later events or processes. While I can't exclude that there has been some spraying, I don't think it has caused these stains, they look too much to me as stains produced by water -- the way they channel around obstrúctions on the wall. Generally I think there is much greyness and deposits from concrete dust in the building. Rainwater is perfectly capable of dissolving substances from fresh concrete dust and reprecipitate a whitish deposit in runners down a wall. Alternatively, there might be a superficial yellowish discoloration of the wall produced by the heat of the explosion, which water can wash away.

<..>
Top of the equipment racks on the right:
http://cryptome.org/2012-info/daiichi-12-0526/pict8.jpg

There are some distinct splotches of white on some of the equipment in this photo which was clearly not there earlier, and which may well be from spraying. However generally the greyness seen I'd assign to a combination photo artefact and concrete dust.

 

[MadderDoc]

Unit2 2nd floor

Spawned by a question on another forum I realize this image is the only published one I know of, showing anything from the 2nd floor of Unit 2 (It is from the landing on the 2nd floor of the north east stairwell)

There would have been made video recordings of at least two Quince tours taking it across the north end of the second floor, however no part of those recordings appear to have been published.

http://gyldengrisgaard.eu/fuku_docs/Dose-of-atmosphere-temperature-measurements-by-robot1_Unit2_2ndfloor.png

 

[SteveElbows]

They spraying I sometimes mention was of anti-scatter/dust suppressant material. I can't find proof right now that they did this for reactor 4, but there are TEPCO videos which show this activity being carried out at other buildings using the cream rather than green substance. It was done late May/early June 2011, here for example is the webcam video of them doing it to reactor 1, the action starts after about 3 minutes of the video. http://www.youtube.com/watch?v=ntjOm7x-KaY&lr=1

Other possibilities seem equally plausible, or some combination, e.g. the anti-scatter agent is eventually partially washed away by rain, or by occasions where they may have overfilled the pool (seem to remember an issue with this happening at some point after they switched to a better way to cool the pool, but could be a false memory).

 

[MadderDoc]

They spraying I sometimes mention was of anti-scatter/dust suppressant material. I can't find proof right now that they did this for reactor 4, but there are TEPCO videos which show this activity being carried out at other buildings using the cream rather than green substance. It was done late May/early June 2011<..>

Probably it would have been some time between June 6th:
http://photo.tepco.co.jp/en/date/2011/201106-e/110611-03e.html
and June 30th:
http://photo.tepco.co.jp/en/date/2011/201106-e/110630-04e.html

The spraying may have been repeated later. I see strong indication of recent spraying with dust inhibitor somewhere near the valve area shown in the photo from July, at http://photo.tepco.co.jp/en/date/2011/201107-e/110706-02e.html.

 

[MadderDoc]

Looking at this Quince capture, I get the impression that a sudden event must have caused quite some flood of very rusty water to pass by here. Alternative explanations I've sought, like leaks, or corrosion in a damp environment does not seem to me to be any good in explaining the pattern and location of the rusty discolouration.

 

[nikkkom]

Looking at this Quince capture, I get the impression that a sudden event must have caused quite some flood of very rusty water to pass by here. Alternative explanations I've sought, like leaks, or corrosion in a damp environment does not seem to me to be any good in explaining the pattern and location of the rusty discolouration.

Unit 2 was full of steam for weeks. Recall footage of its blowout panel steaming day and night.

It's quite possible that steam was condensing on locally colder surfaces and pooling on the nearby floor.

 

[MadderDoc]

Unit 2 was full of steam for weeks. Recall footage of its blowout panel steaming day and night.

It's quite possible that steam was condensing on locally colder surfaces and pooling on the nearby floor.

It is quite certain that steam was condensing inside the building, and that the water once it was condensed was generally transported downwards by gravity. We see the effects of this many places in the building.

However in this photo we see a uniform matte rusty deposition stretching from apparently a significant portion of the floor, and up a foot or so in a curved shape on the rightmost part of the vertical surface of the ventilation shaft. It is this pattern of rusty discolouration I think lacks an explanation. Certainly the rust didn't come there without presence of water, and it is very unlikely rust from local corrosion that we see. Rusty water has not come from above to this part, running down the ventilation shaft, and the discolouration also doesn't seem to fit the expected pattern of splashes from dripping rusty water from above to the nearby floor over a period of time.

 

[Rive]

It is this pattern of rusty discolouration I think lacks an explanation.

If it's a floor penetration (the same style what was found in first floor of U1 as I recall, as an intensive radiation source) then steam coming from the lower level can be an explanation.

 

[MadderDoc]

If it's a floor penetration (the same style what was found in first floor of U1 as I recall, as an intensive radiation source) then steam coming from the lower level can be an explanation.

I am not quite sure which mechanism it is you are proposing. Certainly the floor is penetrated there to make way for the metal duct (and of course to make way for the stairwell itself close by). The same video allows also a view to the metal duct seen from the stairwell landing directly below the landing on the 2nd floor.

Landing on 2nd floor with discoloured metal duct (picture right):

Looking up at same vertical duct from stairwell landing below (picture right):
http://gyldengrisgaard.eu/fuku_docs/Unit2_1-2nd_floor_NE.jpg

 

[etudiant]

Any more information on the water table contamination?
Nihonmatsu is uphill and well inland from the coast. We had been told earlier that TEPCO was keeping the water level in the plant low enough to generate ground water inflows, rather than outflows. Also, the consensus seemed to be that the ground water was flowing towards the ocean, rather than inland. So if your friends input is correct, it really undermines a lot of what we thought we knew about this site.

 

[MadderDoc]

Another Quince 2 survey of Unit 2 is planned for June 13th 2012. On the 2nd floor, the robot is scheduled to use a route from the NE to the NW stairwell as done during previous surveys. Hopefully this time there will be published imagery from along this route which might cast light on the discolouration we've been talking about. On 3rd floor, Quince 2 will meet again with Quince 1, which got stuck there close to the NW stairwell on October 20th 2011

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120612_01-e.pdf

 

[zapperzero]

Another Quince 2 survey of Unit 2 is planned for June 13th 2012. On the 2nd floor, the robot is scheduled to use a route from the NE to the NW stairwell as done during previous surveys.

Apparently the robot is going to be carried up the stairs by a human. Yay for automation!

 

[turi]

Apparently the robot is going to be carried up the stairs by a human. Yay for automation!

Yes, but only from the 1st to the 2nd floor. From the 2nd up to the 5th it seems to climb on its own (judging from the red and blue arrows in the pdf). Do they fear its umbilical could get entangled on the lower floors?

 

[rmattila]

Via ex-skf:


From Sankei Shinbun (6/13/2012):


２号機５階で毎時８８０ミリシーベルト　福島第１

Fukushima Daiichi (I) 880 Millisieverts/hour on 5th floor of Reactor 2

東京電力は１３日、福島第１原発２号機の原子炉建屋内部をロボットを使って調査し、５階の原子炉の真上にあたるコンクリート床付近で、毎時８８０ミリシーベルトの放射線量を計測したと発表した。作業員の５年間の被曝線量上限にあたる１００ミリシーベルトに約７分間で達する値で、東電は「５階に人が立ち入っての作業は困難」とみている。建屋内に目立った損傷はなかったという。

TEPCO announced on June 13 that it conducted the survey of the interior of the Reactor 2 building using a robot, which measured the 880 millisieverts/hour radiation near the concrete floor on the 5th floor right above the reactor. The 5-year cumulative maximum radiation exposure for nuclear workers (100 millisieverts) would be reached in about 7 minutes at that location. TEPCO thinks it will be difficult for [human] workers to enter the 5th floor. According to the company, there was no visible damage to the interior of the building.

国産の災害対策支援ロボット「クインス」の改良型が、５階まで自走して測定した。今回、最高値を計測した場所のコンクリート床の厚さは約２メートルで、格納容器の上端から約３．５メートル離れているという。

The improved version of "Quince", robot developed in Japan for disaster response support, went up to the 5th floor and measured the radiation. The concrete floor with the highest radiation level this time is about 2-meter thick, and about 3.5 meter away from the top of the Containment Vessel.

約４時間にわたる調査で、ロボットの被曝（ひばく）線量は５０５．６ミリシーベルトで、作業員９人の被曝線量は最大で３．９５ミリシーベルトだった。

The robot got 505.6 millisieverts of radiation exposure in the 4-hour survey, and the 9 [human] workers got the max 3.95 millisieverts.

 

[rmattila]

Presentation "Lessons of Fukushima-Daiichi NPP's Accidents to Contribute and to Ensure the NPPs Safety in the World" by Dr. Tadashi NARABAYASHI, Nuclear and Environmental Systems,
Hokkaido University:

http://mntk.rosenergoatom.ru/mediafiles/u/files/dok_en/Naraba.pdf

It appears some consideration is given to filtered venting systems that might in the future be back-fitted to old plants.

 

[SteveElbows]

Map of the reactor 2 robot survey results here:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120614_03-e.pdf

 

[rmattila]

Map of the reactor 2 robot survey results here:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120614_03-e.pdf

It seems the dose rates peak directly above the containment dome, and are at least roughly in line with the dose rates that could be expected to be caused either by a partially exposed core within the RPV, or by the nuclides deposited on the internal surfaces of the dome. I don't think much can be deduced concerning the possible amount of radioactivity that has leaked out from the containment.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120613/0500_suimen.html On 12 June Tepco tried to determine the water level inside unit 2's suppression chamber by measuring the temperature distribution with an infrared camera. The temperature is 38°C in the top part and decreases when you climb down, reaching about 35°C in the lower part. As they could not find an area with a large temperature difference indicating the boundary between the liquid phase and the gas phase, the position of the water surface remains unknown. In the future they will try to determine that water level using different methods.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120612_04-e.pdf Unit 2 S/C Water Level Measurement by an Infrared Camera

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_120614_05-j.pdf This is about a new leak (0.5 to 1 cm above floor) in the Areva decontamination facility, which had been operated in closed loop since May 21.

http://www.tepco.co.jp/en/press/corp-com/release/2012/1205338_1870.html Some more unit 2 thermometers are getting worse (while not completely unusable, they are still available as "reference")

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120613/0500_suimen.html On 12 June Tepco tried to determine the water level inside unit 2's suppression chamber by measuring the temperature distribution with an infrared camera. The temperature is 38°C in the top part and decreases when you climb down, reaching about 35°C in the lower part. As they could not find an area with a large temperature difference indicating the boundary between the liquid phase and the gas phase, the position of the water surface remains unknown. In the future they will try to determine that water level using different methods.

Eh. Maybe it's dry. Or maybe it's full.