Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Bodge]

...and indeed the sensor that has recently shows 201 sV/h has also spiked to high values in the past, so don't know whether to trust it...

That is correct.

On the 7th April the reading at that sensor went from ~30 Sv/Hr to 100(+) Sv/Hr.

I can't find the figures for 9th April - 16th May, but on 17th May 37.6 Sv/Hr was recorded and on the 22nd a peak of 201 Sv/Hr.

 

[Borek]

In my experience it's not *that* volatile. The temperature where it melts is 113C and sublimation occurs about 113.7C at the triple point, and I doubt that rubble pile is that hot.

Sublimation doesn't need 113.7°C - quite the opposite. Iodine sublimates up to this temperature, above it melts first. That's obvious if you look at its http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG .

I've handled Iodine crystals a fair bit, and they don't evaporate away at normal temperatures.

They do. It is all a matter of time, temperature and air movement, from what I remember loses can be easily observed by weighting a solid sample kept in open at room temperature; it is enough to weight it every few minutes on a good analytical scale (0.1 mg). It doesn't necessarily mean loses can be easily observed with a naked eye, but they do exist. This pile is there for several weeks, winds blow for most of the time.

Actually color argument was off, as explained earlier. Still, what I see on my monitor doesn't look like iodine.

 

[Gary7]

I concur that some of the data available on the atmc.jp site is rubbish. For those who read Japanese (or who do not read Japanese but are game to dig around) the METI site has regular updates of the plant parameters. In fact, I believe atmc.jp gets their raw data from the METI updates. Unfortunately atmc.jp is very careless when they upload the data to their site, and so the graphs cannot be trusted.

http://www.meti.go.jp/press/2011/05/20110523006/20110523006-3.pdf
radiation (and other data) for each reactor is on page 7.

 

[SteveElbows]

Is it possible that a fresh blob of corium just dropped into the area near the sensor?

I never know what to think about CAMS readings.

But I can say that when I look back at the reactor 1 drywell CAMS readings I noted in the past, I have just one sensors data for the date range march 20th->april 8th, and it was yoyoing around the 30-50 range over this time, tending to be towards the lower end of this range as time went on. Then it suddenly went up to 100 on the 8th, then back down to 68.3 later on the 8th april. Then no more data was published from unit 1 D/W CAMS all the way until 17th may where we get 2 sensors readings ever since, one of which is usually well below 1 and the other which darts around from either 25-35 or sometimes leaps to 200 or more.

Over the same period S/C CAMS readings for unit 1 were available continually and tended to behave themselves more. Starting off with just one sensor on march 20th, started at 40 and decreased steadily to as low as 8 on april 6th. Bumped back up to 12.9 on april 7th before continuing its decline, down to 6.67 by april 17th. At this time it was joined by a second reading from the S/C, one that was lower at just over 1. By may there was less disagreement between both sensors, and they are both down to around 1 right now.

OK from that I could say that both S/C and D/W readings suggest something happened around april 7th-8th but I could not say what, though I seem to recall some earthquake around this period has ben discussed on this thread in the past weeks. I have forgotten whether there are any similar signs at other reactors, nor whether there was much of interest to be seen from the rather limited CAMS data from earlier on pre march 20th.

 

[jlduh]

Some details about Daini are provided in this article :I wonder how enough seawater pumps at Daini unit 3 could remain safe after being flooded by the OP+6m ~ OP+14m wave reported and depicted on dramatic pictures at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e10.pdf, if they are located outdoors. How can we explain the Daini unit 3 miracle ?

The following attachments are from , a video explaining how the Tokai NPP (located further South in Ibaraki prefecture) survived the March 11th tsunami. The video says that the seawater pumps are enclosed in "more than 6 m" high walls, while the tsunami wave was only "more than 5 m" high. Two pumps survived. The third pump didn't survive because its wall was still under construction and not finished.

Tokai NPP's pump protecting wall is also depicted on a diagram at http://www.asahi.com/photonews/gallery/infographics/110330_toukai2.html and on photographs at http://mytown.asahi.com/areanews/ibaraki/TKY201104190562.html (according to that article, the seawater pumps are also providing cooling for the emergency diesel engines ; One diesel engine stopped because the seawater pump for that engine was flooded through a hole in the wall. The reason for the existence of the hole is that the wall was under construction ; If the wall had been 70 cm lower, the Tokai NPP might have had the same destiny as Fukushima Daiichi)

That's pretty unbelievable... I really think that we will need some time to draw all the conclusions about the technical flaws enlightened by this tsunami. And I'm really convinced that whatever the disaster is already, to some extent, japanese and ALL OF US also have been very lucky when you consider all the parameters involved, with all the uncontrolled risks.

We talked a lot about the EDG and the electric blackout, but really i think the problems related to the pumps and more generally the loss of the cold source have been understated or perhaps not even fully revealed, and the design flaws are also to be considered in this department...

If the EDG can in a way be installed at a much higher level from sea level (if we want to secure them), the problem of the pumps is i think even more problematic to solve. By definition, a seawater pump has to be at sea level, at list the turbine part. Then, of course, the electrical part can be installed at a much higher level, with a long shaft linking the motor and the impeller. I'm not sure that in the Daichi plant, and even at Daini, this is sufficient to secure them though in case of tsunami.

We can also imagine that a so big wave rushing into the impellers can probably break them, or damage them to a certain extent. Then, even with electrical power left, the cold source is lost or diminished. We can also imagine that the intakes can be heavily obstructed by big debris. All these risks explain why the big wall with Y concrete blocks has been constructed into the sea, to create the port where the remaining waves are supposed to be small and the debris kept at a minimum. But a tsunami easily go over this wall... then the cold source is at risk.

The articles reveal an other domino effect with the cooling of the EDG being done with the pumps... which is kind of scary thinking about it! The backup for electrical power is dependent of the same cold source than the one used for the reactors, so no cold source leads to big reactors cooling problem AND electrical backup failure after maybe one hour.

Definitely, this problem related to the pumps and the possible loss of cold source is in my mind as inportant, and even more important perhaps, than the one related to the EDG. And it has not been discussed a lot in reality (here or in the medias), even if i think that at the very beginning, i heard from some reports that Daichi lost its cold source before losing its power (I mean the backup power).

Do we know more on this for the various reactors/plants? Which pumps did fail?

These pumps should at least be put in a bunker if they have to stay close to the sea...

At Daini, from the picture i posted, i don't see the main pumps being inside a building. This picture is from the 12th of March, one day after the tsunami.

 

[jlduh]

As for why some of the real numbers are also high, well this equipment is inside containment and is designed to detect fuel melting, so its not surprising that some numbers are high. Yes if many of these higher numbers were from outside containment then this would indeed be cause for great alarm, but they arent, so don't panic.

As long as "containment contains", you are right...

The question being to what extent it still contains?

 

[Atomfritz]

First plot is for unit 1, and if you will read tepco data you will see that there was big radiation jump in drywell, but we don't know if this is correct, sensor can be damaged, if data is correct than this could be corium which get into drywell from RPV
http://www.tepco.co.jp/nu/fukushima-np/f1/images/11052306_level_pr_data_1u-j.pdf

Thanks! These appear only to have been 2 consecutive readings of 200 Sv.
Now it's all back to "normal" values as before.
Hopefully these are no values from the Tepco PR random generator :)

Ouch. Let's hope only the sensor broke. We'll know soon.

Btw.: Can such values be reached without recriticality?

Yes.
The radiation of a single typical fuel assembly, burnt up to some 40MWd, after one year of decay, is still up to around 500 Sv/h, measured in the distance of 1m in the open air.

Edit:

Is it possible that a fresh blob of corium just dropped into the area near the sensor?

Yes, I also thought that first.
Maybe the reason for the values going down again was no malfunction of the instrument, but just the blob getting washed away by tonnes of water?

http://atmc.jp/plant/rad/

[...] The readings from Unit Five and Unit Six are frightening considering that they were in cold shutdown at the time of the Tsunami.

(Note: Diagrams from left to right are for reactor 1, 2, 3, 5, 6, as reactor 4 is not loaded.)

Regarding reactors 5+6: Joe Neubarth pointed to the high readings in reactors' 5 and 6 drywell.
Even if this is only caused by concurrently failing sensors, this alone imho sheds light about the possibility that unit 5+6 might be cause for later concern.

 

[Gary7]

As mentioned above, please remember that the data from atmc.jp is not accurate. For example, the radiation readings they have supplied for the drywells for #5 and #6, are not radiation readings at all. Rather, it looks as if atmc.jp has mistakenly referenced the temperature readings for the SFPs and plotted these numbers as if they were radiation readings. According to METI, the radiation levels for #5 and #6 are stable and are outside of the scope of their daily plant parameter updates.

 

[SteveElbows]

Anybody know any more about the video mentioned in this story, such as where to find longer version? It was supposedly shot just last weekend.

http://www3.nhk.or.jp/daily/english/23_10.html

 

[jlduh]

More detailed analysis of accumulated turbine building water from march sampling finally published:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110522_04-e.pdf

Any comments?

Well, yes, one more comment: 2 months to release these important datas?

Well well...

 

[Atomfritz]

Thank you for the feedback!

Afaik, the radiation tests on sensors were done with the sensor directly exposed to the radiation.

Hmm, I couldn't find such mentioned.
In the article they rather showed pics of the experiment assembly, using an industrial camera with metal casing and heavy optics around the sensor.
Another pic shows the measuring assembly in the research reactor that was used to bring the camera near enough to the reactor, submerging it about 6 meters in water, protected by a PE insulation.

...it would take quite energetic gamma rays to register on one of these CCD sensors. These would simply be passing through the lens and would not be focused by it.

For instance, cesium produces these.
Maybe this is the reason why even pics shot from points with supposedly substantially less than 100mSv/h from the Fukushima plant area show many, way too many "pixel defects".
Just keep in mind that at least some of these photos probably were taken with conventional consumer cameras made from plastics or light metal, not with heavy industrial use cameras.

That is quite different from the situation when taking a photo. ...
There may be extreme radiation hot spots on the site, but they will not be found using conventional photographs.

This is very important to keep in mind, too.
You could think of the camera sensor as a sort of radiation film, working like a quite insensitive Geiger counter.

Regarding real gamma cameras: here some images from Tepco's gamma cameras: http://www.tepco.co.jp/tepconews/pressroom/110311/index-j.html

See also: http://en.wikipedia.org/wiki/Gamma_camera

Maybe such massings of "temporary pixel defects" in your camera can at least help to find out if your location is definitely unsafe, in case there is a nuclear accident in your vicinity.

 

[Grumalg]

Sublimation doesn't need 113.7°C - quite the opposite. Iodine sublimates up to this temperature, above it melts first. That's obvious if you look at its http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG .



They do. It is all a matter of time, temperature and air movement, from what I remember loses can be easily observed by weighting a solid sample kept in open at room temperature; it is enough to weight it every few minutes on a good analytical scale (0.1 mg). It doesn't necessarily mean loses can be easily observed with a naked eye, but they do exist. This pile is there for several weeks, winds blow for most of the time.

Actually color argument was off, as explained earlier. Still, what I see on my monitor doesn't look like iodine.

<shrug> My bottle of Iodine crystals is approaching 50 years old and has regularly been exposed to 100F+ in summer for months where it's stored. It's all still as crystals at the bottom of the bottle with no visible layer coating the inside of the brown glass bottle. The crystals all still have all the sharp fracture edges too and don't appear eroded.

 

[Atomfritz]

Color that you see depends on the light at the place picture was taken, white balance of the camera and color temperature of your monitor (and other things). In some cases original colors are irreproducible on the screen no matter how you try, in some cases they are changed beyond recognition. So while there is some reddish tint in this place, it accurate shade is questionable.

Shapes do look "brickish" but if you desaturate the image (making it black and white) they no longer look like bricks, just like a random rubble. It is combination of shape and color that tricks you into thinking about bricks.

As a photographer I can attest to this. Also, both digital cameras and the systems we use to view them have a hard time with the color red.

You cannot analyze the color in a photograph unless you've taken it with very specialized equipment. We can see that it is red, but what shade is impossible to say.

Thank you!
These are very good scientific and practical explanations why I was puzzled and tricked by the brickish-colored stuff.
Really a good idea to turn off colors when trying to analyze small picture details!

 

[etudiant]

Thank you for the feedback!

Hmm, I couldn't find such mentioned.
In the article they rather showed pics of the experiment assembly, using an industrial camera with metal casing and heavy optics around the sensor.
Another pic shows the measuring assembly in the research reactor that was used to bring the camera near enough to the reactor, submerging it about 6 meters in water, protected by a PE insulation.


For instance, cesium produces these.
Maybe this is the reason why even pics shot from points with supposedly substantially less than 100mSv/h from the Fukushima plant area show many, way too many "pixel defects".
Just keep in mind that at least some of these photos probably were taken with conventional consumer cameras made from plastics or light metal, not with heavy industrial use cameras.


This is very important to keep in mind, too.
You could think of the camera sensor as a sort of radiation film, working like a quite insensitive Geiger counter.

Regarding real gamma cameras: here some images from Tepco's gamma cameras: http://www.tepco.co.jp/tepconews/pressroom/110311/index-j.html

See also: http://en.wikipedia.org/wiki/Gamma_camera

Maybe such massings of "temporary pixel defects" in your camera can at least help to find out if your location is definitely unsafe, in case there is a nuclear accident in your vicinity.

Not sure that there is even a camera for radiation.
Afaik, the alpha and beta radiation is blocked by the lens, so no sensor impact at all from them.
The gamma radiation just goes right through the camera and the lens, without getting focused or imaged, so any sensor impact is incidental. The sensor would not see hot spots because the lens does not work for the radiation.
There are only very coarse gamma ray sensors, with ultra low resolution. Look up the Fermi astronomical gamma ray telescope, it is probably the state of the art for gamma ray science and it does well to locate the gamma ray source within 10 degrees. TEPCO may be using a pinhole camera, with lots of shielding, but really I have no idea if that would even work given the sensors that are available.
The conventional camera mounted on the cart was surely just to give a visual image of what the gamma ray sensor was looking at.

 

[biggerten]

That is a thoughtful post, jlduh. It must have been the mother-of-all water hammers.

I wonder if they couldn't have some back-up cisterns, although I have no idea of the scale involved, but the ground itself could be a heatsink, maybe this could buy some time.

 

[OmCheeto]

That is a thoughtful post, jlduh. It must have been the mother-of-all water hammers.

I remember water hammer, and the mother of all water hammers, at test depth...

But that was a

 

[dh87]

More detailed analysis of accumulated turbine building water from march sampling finally published:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110522_04-e.pdf

Any comments?

1. The conductivities say that these are 0.5x seawater. Will Areva's precipitation protocols work in seawater? Is this seawater together with all the things that are added to precipitate Cs and Sr what TEPCO claims they'll be using to cool the reactors in perpetuity?

2. Why aren't there any newer measurements of the radioactivity than March 29th?

3. These numbers suggest that every time a number like 30,000 Bq/ml of Cs-137 was reported in the Pacific Ocean that 10,000 Bq/ml of Sr-89+Sr-90 should be understood. I don't think that this is a good thing, but I'll have to read up on the hazards of Sr.

 

[yakiniku]

Please, not a "what this pixel is" again.

Shapes do look "brickish" but if you desaturate the image (making it black and white) they no longer look like bricks, just like a random rubble. It is combination of shape and color that tricks you into thinking about bricks.

Desaturation is one method of numerous color removal methods. See attached picture on how results may not be desired when using simple desaturation (from http://www.inkjetart.com/tips/grayscale/index.html).

I disagree that making the image black and white disproves that the rubble contains brick like shapes. Care must be taken because depending on the algorithm used, detail in different channels can be emphasized or de-emphasized. Also see http://www.cambridgeincolour.com/tutorials/color-black-white.htm

 

[jmelson]

If the EDG can in a way be installed at a much higher level from sea level (if we want to secure them), the problem of the pumps is i think even more problematic to solve. By definition, a seawater pump has to be at sea level, at list the turbine part. Then, of course, the electrical part can be installed at a much higher level, with a long shaft linking the motor and the impeller. I'm not sure that in the Daichi plant, and even at Daini, this is sufficient to secure them though in case of tsunami.

we have a municipal well field that is in a flood plain. They have well pumps somewhere below the water table, and the motors are up on towers above the highest flood expected. I assume they have to have several sets of bearings to prevent the drive shaft from whipping.

Jon

 

[AntonL]

Meltdowns also at No.2, No.3 reactors
http://www3.nhk.or.jp/daily/english/24_16.html

Most of the fuel is thought to have melted down and collected at the bottom of the reactor pressure vessel by 8 PM on March 15th. That's about 101 hours, or 4 days, after the earthquake.

At the No.3 reactor, TEPCO says the fuel could have reached a state of meltdown at around 3 AM on March 14th, about 60 hours after the quake.

However, TEPCO says there is still a chance the damage to the fuel rods is limited.

It says if the water gauges inside the 2 reactors are accurate, their readings show there were sufficient levels of water in the pressure vessels to prevent a total meltdown.
Tuesday, May 24, 2011 11:38 +0900 (JST)

Regarding the cooling of reactor 3: The 21 m³/h cooling water showing no added benefit was soon reduced to 18 m³/h being pumped into unit 3 and temperatures remaining well above 100^oC proves that most of the water does not even touch the molten core at the bottom of the reactor.

[PLAIN]http://k.min.us/ic1VA0.JPG

The huge amount of cooling water flowing past the core and the onwards to the environment (outside containment) adds to a further problem, Tepco have given notice that pumping away the trench water may soon stop as they have nowhere to store this water. They have pumped this water into the basements of the radioactive waste treatment buildings - but these basements are now nearly full. http://www3.nhk.or.jp/daily/english/23_25.html

 

[Jorge Stolfi]

I see I have a reputation which is following me , and it's not a good reputation :grumpy:

Actually it is those telephoto images that have a bad reputation here. They have been used by some posters to argue that Unit #4 is leaning --- a claim that is highly unlikely given the structure of the building, and seems to be negated by all other pictures of the building.

 

[Jorge Stolfi]

Still, what I see on my monitor doesn't look like iodine.

There are two other arguments against that color being due to iodine. Most of the iodine at Fukushima would be byproduct of nuclear fission, so most of it would be the radioactive isotope. A quantity of iodine large enough to be visible would be much more radioactive than what is reported for that pile of rubble. Isn' t that so?

Moreover, that pile has been bulldozed, so any material that was originally on the ground should be all mixed up with other rubble (see the green " plastic" pieces for example). The fact that the red tint is all in one place at the top of the rubble argues for it having been sprayed after the bulldozing.

 

[zapperzero]

Actually it is those telephoto images that have a bad reputation here. They have been used by some posters to argue that Unit #4 is leaning --- a claim that is highly unlikely given the structure of the building, and seems to be negated by all other pictures of the building.

Umm... I'm afraid I was the first to raise such a possibility here :D

 

[htf]

The gamma radiation just goes right through the camera and the lens, without getting focused or imaged, so any sensor impact is incidental. The sensor would not see hot spots because the lens does not work for the radiation.

That's the point. Pixel errors would be randomly distributed all over the picture. But since bright spots will stand out in dark areas of a picture we could get the impression of a resolution.

But what about the memory of the camera? Or are the radiation levels far too low to cause as significant number of bit flips? But again this wouid only produce randomly distributed pixel errors.

 

[~kujala~]

TEPCO says that based on hearing from workers, it has confirmed that the system was manually shut down at 3:03 PM.
It said this step was made based on a manual, in order to prevent damage to the reactor, because the temperature of the water to cool the No.1 reactor had dropped sharply.

http://www3.nhk.or.jp/daily/english/24_18.html

Has it been discussed here what might be the reason for this sudden decline in cooling water temperature of unit #1 on March 11th 3:03 PM?

From wikipedia:
Earthquake occurred at 2:46 PM.
Tsunami hit 41 minutes later, that's 3:27 PM.
The diesel generators were disabled at approximately 3:41 PM.

So it's not a tsunami-related thing. That's something to begin with...

 

[elektrownik]

http://www3.nhk.or.jp/daily/english/24_18.html

Has it been discussed here what might be the reason for this sudden decline in cooling water temperature of unit #1 on March 11th 3:03 PM?

From wikipedia:
Earthquake occurred at 2:46 PM.
Tsunami hit 41 minutes later, that's 3:27 PM.
The diesel generators were disabled at approximately 3:41 PM.

So it's not a tsunami-related thing. That's something to begin with...

Maybe cooling ? There are different reports about generator's cooling, some that generators were oil cooled, some that water, someone write here that they were sea water cooled and after tsunami they lost water source, or different option which was also described in some articles that tsunami damaged oil tanks, or another (which was posted a long time ago on tepco worker blog) that tsunami damaged fuel tanks, if it is cooling problem then it is possible that they shut down generators because they were overheating

 

[Cire]

Meltdowns also at No.2, No.3 reactors
http://www3.nhk.or.jp/daily/english/24_16.html


Regarding the cooling of reactor 3: The 21 m³/h cooling water showing no added benefit was soon reduced to 18 m³/h being pumped into unit 3 and temperatures remaining well above 100^oC proves that most of the water does not even touch the molten core at the bottom of the reactor.

That's quite the jump from questionable temperature data to absolute proof. How do you see the lower pressure vessel sitting at ~100C (bold red) with a "molten core" only a few inches away?

The RPV mounting flange is 100C hotter then the bottom of the pressure vessel? The temperature data isn't trustworthy. The calibration and offsets where changed when the sensors exceeded their rated temperatures early in the accident.

 

[Borek]

<shrug> My bottle of Iodine crystals is approaching 50 years old and has regularly been exposed to 100F+ in summer for months where it's stored. It's all still as crystals at the bottom of the bottle with no visible layer coating the inside of the brown glass bottle. The crystals all still have all the sharp fracture edges too and don't appear eroded.

I am afraid it doesn't mean much. Bottle is always full of saturated iodine vapor and mass transfer occurs between crystals all the time. Large crystals are more stable, so even if the smaller ones are created on the glass surface when the bottle is cooling, later they will slowly disappear at the cost of the larger ones growing back. (This is not different from precipitate aging used in gravimetric analysis to make filtration easier - same process, just in solution.)

 

[Borek]

what about the memory of the camera? Or are the radiation levels far too low to cause as significant number of bit flips? But again this would only produce randomly distributed pixel errors.

That's not that simple. Images are stored in compressed formats, so bit flips will change not just single pixels, they will break huge parts of the image (assuming file will be still readable). These are two jpg images - original, and one that has 10 random bits flipped:

Effects don't have to be that dramatic, sometimes they are difficult to spot, but as you see it is not a matter of single pixels changing their color.

Edit: note that the bottom image is rendered differently in different browsers - my guess is that some abort rendering after it is apparent that the data stream is broken.

 

[tsutsuji]

A nice computer animation of the Ocean pollution data from March 11th to May 21st :

 

[clrcdd]

i apologize if this has been posted earlier. below links to 3 presentations from the icapp meeting special japan session.

https://www.sfen.fr/content/download/30655/1616957/file/1-ICAPP_Omoto2.pdf
https://www.sfen.fr/content/download/30419/1606950/file/2-ICAPP Fukushima Accident_Masui.pdf
https://www.sfen.fr/content/download/30420/1606953/file/3-ICAPP-0503P_Sato.pdf

source:
https://www.sfen.fr/ICAPP-11

 

[MiceAndMen]

i apologize if this has been posted earlier. below links to 3 presentations from the icapp meeting special japan session.

https://www.sfen.fr/content/download/30655/1616957/file/1-ICAPP_Omoto2.pdf
https://www.sfen.fr/content/download/30419/1606950/file/2-ICAPP Fukushima Accident_Masui.pdf
https://www.sfen.fr/content/download/30420/1606953/file/3-ICAPP-0503P_Sato.pdf

source:
https://www.sfen.fr/ICAPP-11

Interesting even if they're a little out of date. 3 weeks ago they hadn't yet concluded that unit 1's RPV was badly damaged, and none of the PDFs show that. On page 16 of the first link there is a mistake: Unit 2's blowout panel was opened prior to the explosion of Unit 3, whereas the PDF says Unit 3's explosion caused the panel to open. Maybe I'll find some time soon to look them over a little further. There doesn't appear to be any really new information at first glance, but thanks for the links.

 

[clancy688]

https://www.sfen.fr/content/download/30420/1606953/file/3-ICAPP-0503P_Sato.pdf

Page 17...

Tsunami - Initial Design Basis 3.1 m, Revised Design Basis 5.7 m.

We already crucified them for only building a 5.7 m tsunami wall in a region where 10+ m tsunamis are common. Don't tell me now the initial tsunami safety was even below that...

 

[tsutsuji]

i apologize if this has been posted earlier. below links to 3 presentations from the icapp meeting special japan session.

https://www.sfen.fr/content/download/30655/1616957/file/1-ICAPP_Omoto2.pdf
https://www.sfen.fr/content/download/30419/1606950/file/2-ICAPP Fukushima Accident_Masui.pdf
https://www.sfen.fr/content/download/30420/1606953/file/3-ICAPP-0503P_Sato.pdf

source:
https://www.sfen.fr/ICAPP-11

Thanks.

I need help reading the acronyms page 9 of https://www.sfen.fr/content/download/30655/1616957/file/1-ICAPP_Omoto2.pdf :

EE ?
SAM ?
AMG ?
Rx ?

I find strange that the seawater pumps, while being pointed out in yellow circles page 7, are no longer mentioned page 9. I miss a "saved Tokai NPP" line on page 9.

It is aslo a bit strange that although the conclusion on page 9 was "Availability of UHS (ultimate heat sink) (...) does not seem to be a decisive factor", the conclusion on page 29 is the need for "diversified" UHS and diversified power with air-cooled diesel generators.

Page 15/41 (14) of https://www.sfen.fr/content/download/30419/1606950/file/2-ICAPP Fukushima Accident_Masui.pdf is interesting with a few details about the "Additional Facility" (water purification unit).
Page 31/41 (30) of https://www.sfen.fr/content/download/30419/1606950/file/2-ICAPP Fukushima Accident_Masui.pdf is interesting with a few details on the seismic isolated building.

 

[clancy688]

http://ex-skf.blogspot.com/2011/05/mainichi-english-agency-gears-up-to.html

Wait... what? Oo

Monju is a fast breeder reactor that uses sodium as coolant, which catches on fire on contact with air. It uses MOX-fuel.

3.3-tonne, 12-meter "In‐Vessel Transfer Machine" fell into the reactor vessel on August 26, 2010. The manager at the plant in charge of fuel exchange committed suicide in February this year.