Japan Earthquake: Nuclear Plants at Fukushima Daiichi

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The Fukushima Daiichi nuclear plant is facing significant challenges following the earthquake, with reports indicating that reactor pressure has reached dangerous levels, potentially 2.1 times capacity. TEPCO has lost control of pressure at a second unit, raising concerns about safety and management accountability. The reactor is currently off but continues to produce decay heat, necessitating cooling to prevent a meltdown. There are conflicting reports about an explosion, with indications that it may have originated from a buildup of hydrogen around the containment vessel. The situation remains serious, and TEPCO plans to flood the containment vessel with seawater as a cooling measure.
  • #8,071
zapperzero said:
I see I have a reputation which is following me , and it's not a good reputation

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.
 
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  • #8,072
Borek said:
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.
 
  • #8,073
Jorge Stolfi said:
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
 
  • #8,074
etudiant said:
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.
 
  • #8,075
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...
 
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  • #8,076
~kujala~ said:
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
 
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  • #8,077
AntonL said:
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 100oC 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.
 
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  • #8,078
Grumalg said:
<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.)
 
  • #8,079
htf said:
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:

chalwa01_1.jpg


chalwa01_1a.jpg


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.
 
  • #8,080
A nice computer animation of the Ocean pollution data from March 11th to May 21st :
 
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  • #8,082
clrcdd said:
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.
 
  • #8,083
  • #8,084
clrcdd said:
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.
 
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  • #8,085
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.
 
  • #8,086
tsutsuji said:
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 ?
SAM = Severe Accident Mitigation
AMG probably = Accident Mitigation Guide/Guideline/Guidance

Rx = Reactor, R/B = Reactor Building

EE could be emergency electrical or emergency equipment.

Acronyms can have multiple meanings, so context is important.
 
  • #8,087
SteveElbows said:
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.

there is more data here (until 4/24): http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_1u.pdf (download as csv as well from this page: http://www.tepco.co.jp/nu/fukushima-np/)

i have attached a diagram of the D/W CAMS values (x is hours after scram, y is Sv/h).

EDIT: same diagrams for unit 2 and 3 look much 'smoother'
 

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  • #8,088
bytepirate said:
there is more data here (until 4/24): http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_1u.pdf (download as csv as well from this page: http://www.tepco.co.jp/nu/fukushima-np/)

i have attached a diagram of the D/W CAMS values (x is hours after scram, y is Sv/h).

EDIT: same diagrams for unit 2 and 3 look much 'smoother'

Thanks. I had seen that data before, but I forgot to compare it to the original data that I had been recording manually from each status update.

By looking at both sets of data, it seems highly likely that the reason they originally stopped publishing unit 1 CAMS for the drywell after April 8th is not just because it spiked upwards and then wobbled all over the place, but because they got the 2nd sensor working at this time and it completely disagrees with what the other sensor was saying, by quite some orders of magnitude. I am not really sure why they started showing it on the overall status updates again as of may 17th, because the 2 sensors still disagree a lot.
 
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  • #8,090
clrcdd said:
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

Hi, thanks for the infos. I just wanted to mention that SFEN is acronym for Société Française d'Energie Nucleaire and is a french association which is a pro nuclear lobby . I know that because I've been personnally a member of this association... a long time ago!

I just wanted to let you know this because some of the conclusions may be not only "scientifically neutral" :smile:
 
  • #8,091
AntonL said:
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 100oC 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

As i said earlier, I'm afraid that the ultimate containment will be... the ocean.

Time is running...
Contaminated water is flowing...
 
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  • #8,092
Borek said:
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).
You are right! So we should ask Tepco whether they observed any corrupted pictures.
 
  • #8,093
I just wanted to mention here this post from andybwell on an other thread:

https://www.physicsforums.com/showpost.php?p=3317685&postcount=106

Well, at the beginning of Gunderson's video above, he is saying :we know that n°1 reactor was already in course of meltdown and the containment was leaking before tsunami hit...

Is this supported by some statements or data or facts?

By the way, how would you describe the defects he is showing (holes, cracks, etc.)?

Personnaly, threatening may be an adequate word.
 
  • #8,094
AntonL said:
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

However, if they study the CAMS data http://k.min.us/ilrLwi.pdf" then they would note a spike in the readings between 13:00 and 15:25 on 15 March which would make the event even a couple of hours earlier, - a nice correlation between a theoretical study and actual field readings.
 
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  • #8,095
jlduh said:
I just wanted to mention here this post from andybwell on an other thread:

https://www.physicsforums.com/showpost.php?p=3317685&postcount=106

Well, at the beginning of Gunderson's video above, he is saying :we know that n°1 reactor was already in course of meltdown and the containment was leaking before tsunami hit...

Is this supported by some statements or data or facts?

some facts:
1. Reactor http://search.japantimes.co.jp/cgi-bin/nn20110517x1.html" after the quake and before the tsunami (Tepco should publish their official findings regarding this soon as instructed by NISA)

2. http://search.japantimes.co.jp/cgi-bin/nn20110516a3.html" at unit 1 well before the explosion indicating a possible breach in containment caused by earthquake.

So for a change, Gunderson statements are (part) true.
 
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  • #8,096
Borek said:
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).

Indeed, I get a sample of that from my satellite TV whenever a storm gets between the sat and the antenna.

Penetrating radiation should flip bits at random in every consumer-grade digital circuir --- not just in the image sensor, but also in the compression chips and in the interfacing processor.

In the first T-hawk videos, whenever the drone was getting too close to interesting spots --- such as the #4 SFP, or the service floor of #3 --- the image would dissolve into compression chaos, and I had the impression that the drone would then back away. I thought it could be bad reception perhaps due to all that rebar shielding the signal. But perhaps radiation was to blame?
 
  • #8,097
I have two questions.

A few weeks ago we saw estimations of total amount av radioactive materials emitted to the atmosphere made by NSC and I think Tepco. Should these estimations be updated now since we since then now know there has been a meltdown in #1, #2, and #3?

Has anyone made an estimation yet of the total amount of radioactive material emitted directly to the sea?

Thanks.
 
  • #8,098
Giordano said:
A few weeks ago we saw estimations of total amount av radioactive materials emitted to the atmosphere made by NSC and I think Tepco. Should these estimations be updated now since we since then now know there has been a meltdown in #1, #2, and #3?

AFAIK these estimates didn't care the slightest about what was going on in the NPP. Whether there was a core melting down or Osama bin Laden throwing with spent fuel, it wasn't of concern.
They only measured the radiocativity in the air and made estimates with spread and dilution how much was probably released during the course of the accident.

Has anyone made an estimation yet of the total amount of radioactive material emitted directly to the sea?

TEPCO did it for one leak.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e2.pdf

But nobody has any idea how much contaminated water really escaped.
 
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  • #8,100
ascot317 said:
Exactly my thought... and... "How?"

How is it technically possible to let this happen??

And... "Let's cool it with seawater" (yes, that's sarcasm).

Sarcasm seems uncalled for.
When that decision was made, quite reluctantly and perhaps too late, there was no other way to try to cool the reactors.
We should always remember the site is in the middle of a disaster zone, with 25,000 people dead and many times that number homeless.
 

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