Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[AntonL]

Broken pipes discovered at Hamaoka's No. 5 nuclear reactor
http://www.asahi.com/english/TKY201105210146.html

[PLAIN]http://www.asahicom.jp/english/images/TKY201105210310.jpg

At least 20 of the approximately 21,000 titanium pipes, which are 0.5 millimeters thick and have a diameter of 3 centimeters, had cracks or holes in them.

The damage appears to have been caused by the end cap of a nearby pipe, which came off and was found on the ground. It possibly became dislodged due to worn welds, but the details are yet to be confirmed, according to a Chubu Electric official

 

[zapperzero]

radiation measurement live from Japan
μSv/h

Iitate village, Fukushima pref
39.5 km away from Fukushima Daiichi
http://www.ustream.tv/channel/8000164

Thanks! This one in Iitate is on a 30-second average mode, varying wildly between 0.4 and 0.9 uSv/h

Many seem uncalibrated, though :(. One is dead, no battery :P.

 

[Atomfritz]

Yeah, I kind-of ignored that subject because those white dots are definitely an image artifact that I have never seen before. The color white comes when the bayer-filter registers all three color channels as fully saturated. The only artifact that comes close is hot pixels when shooting with high ISOs and long exposure, but they aren't white, or very rarely are.

The "funny" pixels are not always white. It looks like impulse noise affecting one or more color components to me. I've seen artifacts like these when the CCD power source had noise or when there was some RF interference. There can be several places where the noise could be introduced: in CCD, in ADC converter or when transfering digital data from imager to the processing system. Sometimes the data transfers are done using YUV data channels, so a single bit off could change the overall luminance or color. It's not at all certain that radiation is causing this.

Maybe it's not certain, but it is very probable that the suspicious "bad pixels" are caused by radiation.

Some background to this: Dynamic circuitry, like DRAMs and many processors is very sensitive to radiation from structure micron size about short before the megachips' era.

About 25 years ago, DRAM chips producers began commonly to provide the chips with a thin dense coating directly on the finished die to protect the small charges of the data storage capacitors from getting altered by particles and photons emitted just by the plastic casing of the chips.
This is reflected in the soft error specifications of the DRAM manufacturers.

However, little proven facts are available regarding modern consumer digital cameras and the effects of radiation.

Here an interesting article of a Cambridge University team working on a radiation-hardened camera sensor, explaining some of the radiation effect in the semiconductor: http://iopscience.iop.org/1748-0221/6/03/C03003/pdf/1748-0221_6_03_C03003.pdf

I found another report on evaluating CCD camera sensors for use in highly irradiated accelerator areas, regarding both durability and temporary image distortions.

They used a TRIGA research reactor as radiation source to find out if a CCD camera can survive usage in an accelerator.

They found out that some camera sensors can survive up to 100 Gy, but also that temporary image distortions ("pixels" for those who hate this word ;) ) definitely show up very clearly at 100 mSv/h.

http://img852.imageshack.us/img852/3290/hotspotcamera.jpg

For the detailed report please see here: http://www.isprs.org/proceedings/XXXVI/part5/paper/MARB_645.pdf

So I think that the strange spots you can very clearly see in the high-resolution picture linked here ( http://www.tepco.co.jp/en/news/110311/images/110519_3_4.jpg ) are still quite interesting.

We have to consider that the men walked in areas up to around 2 Sv/h!

Maybe it is just that we just don't get shown the really disturbing images completely speckled with radiation noise that one could expect at 2 Sv?

 

[Bodge]

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

Btw.: Can such values be reached without recriticality?

Not according to TEPCO.

http://www.tepco.co.jp/en/press/corp-com/release/11042713-e.html"

So it's either:

a.) Sensor malfunction
or
b.) A "transient criticality".

What does the supporting evidence suggest?

 

[Grumalg]

Iodine is too volatile to stay in open place for that long. Besides this is not an iodine color.

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.

I've handled Iodine crystals a fair bit, and they don't evaporate away at normal temperatures. I've melted/sublimated it into purple vapors and seen what surfaces the vapor deposits on look like and how such deposits persist for extended periods.

The resulting deposits from those vapors have often appeared similar in color to what shows in the picture depending on the nature of the surface and how heavy the deposit. The resulting colors I've seen have ranged from light red/brown through dark bluish purple (almost dark enough to look black).

Not saying it has to be Iodine, but I don't think it's all that far fetched that Iodine deposits could discolor things that were exposed to it as a vapor, nor that such deposits could persist at temperatures below 100C.

The real question is whether the Iodine vapor was present in sufficient concentration to form a visible deposit. That I'm not so sure about.

 

[etudiant]

Maybe it's not certain, but it is very probable that the suspicious "bad pixels" are caused by radiation.

Some background to this: Dynamic circuitry, like DRAMs and many processors is very sensitive to radiation from structure micron size about short before the megachips' era.

About 25 years ago, DRAM chips producers began commonly to provide the chips with a thin dense coating directly on the finished die to protect the small charges of the data storage capacitors from getting altered by particles and photons emitted just by the plastic casing of the chips.
This is reflected in the soft error specifications of the DRAM manufacturers.

However, little proven facts are available regarding modern consumer digital cameras and the effects of radiation.

Here an interesting article of a Cambridge University team working on a radiation-hardened camera sensor, explaining some of the radiation effect in the semiconductor: http://iopscience.iop.org/1748-0221/6/03/C03003/pdf/1748-0221_6_03_C03003.pdf

I found another report on evaluating CCD camera sensors for use in highly irradiated accelerator areas, regarding both durability and temporary image distortions.

They used a TRIGA research reactor as radiation source to find out if a CCD camera can survive usage in an accelerator.

They found out that some camera sensors can survive up to 100 Gy, but also that temporary image distortions ("pixels" for those who hate this word ;) ) definitely show up very clearly at 100 mSv/h.

http://img852.imageshack.us/img852/3290/hotspotcamera.jpg

For the detailed report please see here: http://www.isprs.org/proceedings/XXXVI/part5/paper/MARB_645.pdf

So I think that the strange spots you can very clearly see in the high-resolution picture linked here ( http://www.tepco.co.jp/en/news/110311/images/110519_3_4.jpg ) are still quite interesting.

We have to consider that the men walked in areas up to around 2 Sv/h!

Maybe it is just that we just don't get shown the really disturbing images completely speckled with radiation noise that one could expect at 2 Sv?

Afaik, the radiation tests on sensors were done with the sensor directly exposed to the radiation.
That is quite different from the situation when taking a photo. The sensor then is behind a massive lens, which is opaque to all but visible and near IR light. Alpha and beta radiation is excluded therefore, plus 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.
There may be extreme radiation hot spots on the site, but they will not be found using conventional photographs. A scanning radioactive source meter would be more promising, but these are pretty primitive designs and not especially easy to deploy.

 

[StrangeBeauty]

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

Btw.: Can such values be reached without recriticality?

Not according to TEPCO.

http://www.tepco.co.jp/en/press/corp-com/release/11042713-e.html"

So it's either:

a.) Sensor malfunction
or
b.) A "transient criticality".

What does the supporting evidence suggest?

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

 

[jlduh]

Thanks! This one in Iitate is on a 30-second average mode, varying wildly between 0.4 and 0.9 uSv/h

Many seem uncalibrated, though :(. One is dead, no battery :P.

Well, now in Iitate i read more than 4,2 (I guess microSievert/h)... Which is much more.

 

[SteveElbows]

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

Where in each plant are those outrageous Sieverts per Hour readings coming from? Is it in the control centers? Is there something wrong with the data? Does Sv/hr in Japan mean something different from what I think it means. The readings from Unit Five and Unit Six are frightening considering that they were in cold shutdown at the time of the Tsunami.

The graphs on that site are not good, plenty of errors.

For a start for unit 1 they say that one CAMS reading is from D/W and other from S/C. Its not true, both the sets of data they are showing are for D/W, and they are not showing any S/C readings. TEPCO publish 2 D/W readings and 2 S/C readings, and it is important to note that the unit 1 D/W readings were unavailable for many days due to presumed sensor problems, 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.

As for Units 5 and 6, the site is complete rubbish, it is using wrong data. There are no CAMS readings for reactors 5 and 6, and I have worked out what data it is using by mistake. These numbers are the reported temperatures of the spent fuel pools at units 5 & 6 and should certainly not be in Sv/h. Here is the raw data that I can get to match up, eg look at pool temps at 12:00 on 21st and they match the bogus Sv/h readings on that graph site:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11052306_temp_data_56u-e.pdf

So I would not recommend using that atmc.jp site, use TEPCOs data.

http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html

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.

 

[Bodge]

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

If I'm understanding it correctly, the TEPCO doc I linked to precludes the possibility of anything in the drywell being *that* radioactive after ~1600 hours.

 

[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