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.
  • #3,391
bytepirate said:
you can see the cerenkov light on the webcam pics (http://www.tepco.co.jp/nu/f1-np/camera/index-j.html only at night of course). a couple of days ago it was not directly visible, but you could make it visible with photoshop. no idea, if it grew stronger, or if the webcam is adjusted.

someone monitored the spot since march 21st:
http://www.abovetopsecret.com/forum/thread672665/pg433 (3rd post on that page)

in the current webcam pic, there is no cherenkov visible anymore.
i really hope, that the crack in the SFP (#4) has not been enlarged by the recent earthquake(s).
 
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Engineering news on Phys.org
  • #3,393
Good demonstration of how Zircaloy is embrittled by dry heat PLUS water:

http://www.fairewinds.com/content/nuclear-engineer-arnie-gundersen-demonstrates-how-fukushimas-fuel-rods-melted-and-shattered"

Yes it is Gundersen :rolleyes:
 
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  • #3,394
Steam, Nitrogen Leak

Radioactive steam and nitrogen is escaping from the containment vessel at the No. 1 reactor and the company is checking radiation levels around the reactor, spokeswoman Megumi Iwagarbagea said by phone today.

Tepco started injecting nitrogen into the vessel to reduce the risk of a hydrogen explosion. The pressure inside the vessel is rising more slowly than expected, indicating a leak, Iwagarbagea said. Work continues at the reactor and other parts of the Fukushima Dai-Ichi power station, she said. http://www.bloomberg.com/news/2011-04-11/tepco-chief-rebuffed-in-fukushima-as-crisis-enters-second-month.html
 
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  • #3,395
MadderDoc said:
Well, I am a chemist, and I can't see how the chloride from the seawater could be chemically changed to Cl2 in the reactor environment -- and even less how it could accumulate there.

I was thinking something like described in the following paper: http://www.wmsym.org/archives/2002/Proceedings/28E/73.pdf
Alpha-particle irradiation of 5 M NaCl results in the formation of transitory equilibrium system of Cl3-, Cl2, HClO, ClO-, Cl- [9]. According to Büppelmann K., Kim J.I., and Lierse Ch., at pH<7, the formation of chlorine gas is favored. At 4<pH<7, the formation of hypochlorous acid (HClO) is observed while at pH>7, the formation of hypochlorite (ClO-) is preferential [10]. This change may be easily explained by H+ + ClO- \leftrightarrow -HClO equilibrium (pKa =7.23 in pure water).

But as I said, I have no idea of the relevance of such a reaction to the situation at hand, and as you point out:
Cl2 is a strong oxidant species and -- if generated -- it would quickly react with e.g. metal and in turn revert to chloride ion.
 
  • #3,396
Here is another good overview of the Fukushima event.
www.vgb.org/vgbmultimedia/News/Fukushimav15VGB.pdf


Regarding the chemistry - it's complicated. The introduction of seawater into a core of stainless steel (SS304) and Zircaloy-2 complicates an already complicated situation. Radiolysis is a factor not normally considered in chemistry. One the fuel breaches it becomes even more complicated.

The Zr-liner on the inside of the cladding will react readily with steam. Zr-2 is normally resistant to corrosion, but high temperatures reduce the corrosion resistance, and the presence of ferric chloride also significant reduces corrosion resistance of Zr-2.

Some reactor accident analyses indicate the presence of I2. Iodine is a fission product in the fuel, as is cesium. If elemental iodine can be formed, then possibly elemental Cl2 could also form from similar reactions. On the other hand, chlorine is very reactive. Should the Cl2 react with steam, Zr-2, or stainless steel, or any of the metal oxides? If the core is dry (in steam, without water), what is the environment in the steam? Hydrogen is certainly generated because we now that significant hydrogent was generated at Units 1 and 3, and that hydrogen subsequently detonated.
 
  • #3,397
I have no idea how Gundersen sourced this NRC report (from 26 March) but it discusses ejected fuel being bulldozed twice:
"...fuel may have been ejected from the pool (based on information from TEPCO of neutron sources found up to 1 mile from the units, and very high dose rate material that had to be bulldozed over between Units 3 and 4. It is also possible the material could have come from Unit 4.)"

"Fuel particulates may have been ejected from the pool (based on information of neutron emitters found up to 1 mile from the units, and very high dose rate material that had to be bulldozed over between Units 3 and 4. It is also possible the material could have come from Unit 3.)"http://www.fairewinds.com/content/nrc-report-official-use-only-fukushima-assessment-march-26th-2011"

How can ejected fuel be a neutron source without fission taking place?
 
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  • #3,398
AntonL said:
There is no tsunami wall around the nuclear power plant I can only see a breakwater to protect the harbour and the intakes from wave action.

I still maintain that ground floor elevation of the nuclear reactors is determined by basic sizing constraints to keep the basement above sea water level.

The tsunami study of 2007 that is cited earlier in this forum and proudly presented by Tepco that it calculated a tsunami of 5.7metres for design, was an afterthought and not a original design parameter. (If they looked at historical data they should have been extremely worried since the study which they preferred to ignore) The model for the Tsunami was developed in 2002 but the reactor was built in the sixties. If Tsunami was an consideration for design back in the sixties they would have fallen back on historic records.

In http://k.min.us/ikGIkI.JPG (your excerpt of http://www.meti.go.jp/press/2011/04/20110409007/20110409007-3.pdf at https://www.physicsforums.com/showthread.php?p=3237632#post3237632) we can see that there is a difference in the design of Reactors 5 & 6, where the ground floor elevation is 13 m instead of 10 m at Reactors 1, 2, 3 & 4. I wonder how Tepco explains that difference. If they say that this 13 m is intended to make reactors 5 & 6 safer, this would amount to admit that, conversely, the design of reactors 1, 2, 3, & 4 was unsafe. In that sense, the 13 m design at reactors 5 & 6 is a good candidate for the "later study" NUCENG is imagining :

NUCENG said:
Once the plant was built, it is tough to move it to higher ground. If a later study indicated a bigger threat existed, it would be up to the regulators to insist on additional precautions, because plant owners might be reluctant to pay for the new work. That kind of thing has happened repeatedly here in the US. Japanese Industry/Government relationships are reputedly somewhat backwards by the US model.

NUCENG said:
If the Japanese didn't consider tsunamis during initial plant siting and design I would be floored - after all tsunami is Japanese for harbor wave.

Please have a look at the following Asahi Shinbun article (previously mentioned by Shogun338 at https://www.physicsforums.com/showthread.php?p=3233994#post3233994 ) which compares the Daiichi (No. 1) and Daini (No. 2) plants :

When the Fukushima No. 1 plant was being built, Japan was importing technology from the United States and learning from a more advanced nuclear power nation.

[...]

According to sources, the locations of emergency generators and the seawater pump structure were also based on a GE design.

[...]

After Toshiba and Hitachi gained experience in constructing nuclear plants, they located emergency generators and seawater pumps within buildings. Yet those safety improvements were never reflected in changes at the Fukushima No. 1 plant.
http://www.asahi.com/english/TKY201104060126.html

I am also wondering whether the following scenario in NUREG-1150 is not more or less similar with what happened at Fukushima :

Peach Bottom seismic analysis : [...] Peach Bottom has four emergency diesel generators, all shared between the two units and four station batteries per unit. Thus, there is a high degree of redundancy. However all diesels require cooling provided by the emergency service water system, and failure to provide this cooling will result in failure of all four diesels.

NUREG-1150 pages 8/16 - 8/17 :
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1150/v1/sr1150v1part-3.pdf

This sounds close enough to the "D/G Inoperable due to Tsunami flood" analysis on page 12 of http://www.nisa.meti.go.jp/english/files/en20110406-1-1.pdf and professor Yoshiaki Oka's analysis :

Emergency DGs started at the earthquake. But Tsunami damaged ultimate heat sinks (sea water pumping and cooling system) of units 1F1-4. caused common cause failure

page 5 at http://www.f.waseda.jp/okay/news_en...ower_Plants_suffered_big_eart_quake110331.pdf

Some mysterious Mitsubishi emplyee, Haruki, is also being quoted as saying :

the sea water pump systems of all the NPPs used for cooling of diesel generator and ultimate heat sink were completely lost by the tsunami.
http://www.it-ru.de/forum/viewtopic.php?t=196992&start=630

Erick Krock, who is probably not a nuclear specialist concludes :

It is possible that if the designers had placed two or three of the backup diesel generators at a higher elevation with secure, flexible, earthquake-resistant underground power cable connections to the reactors, we wouldn’t be having any problems with these reactors right now.
http://www.voximate.com/blog/article/1058/failover-backup-systems-redundant/

But you would still need to cool these higher elevated Diesel Generators with a distinct and secure cooling system.

The relevance of NUREG-1150 (albeit with a link to part 2 : http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1150/v1/sr1150v1part-2.pdf ) was suggested in http://www.bloomberg.co.jp/apps/news?pid=90920000&sid=aQkgwhzUb4pI (18 March 2011)

The following part of NUREG-1150 is also being quoted by Joseph E. Shepherd :

The total probability of losing AC power long enough to induce core damage is relatively high, although still low for a plant with Peach Bottom's design.

p 37 of http://www.galcit.caltech.edu/~jeshep/fukushima/ShepherdFukushima9April2011.pdf
 
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  • #3,399
NUCENG said:
Tsunamis, seiches, hurricane storm surges, and external flooding have been considered in reactor site licensing in the US since the 1960s. If the Japanese didn't consider tsunamis during initial plant siting and design I would be floored - after all tsunami is Japanese for harbor wave.

Once the plant was built, it is tough to move it to higher ground. If a later study indicated a bigger threat existed, it would be up to the regulators to insist on additional precautions, because plant owners might be reluctant to pay for the new work. That kind of thing has happened repeatedly here in the US. Japanese Industry/Government relationships are reputedly somewhat backwards by the US model.

Yet, we have San Onofre in San Diego County which is sitting east of San Clemente island. There is an earthquake fault running just up the eastern coast line of San Clemente with a very large and sharp depression off shore and an unstable island above. Somehow I sincerely doubt that they considered this when they built San Onofre. I am not and have not been impressed with site engineers. Fukushima is just a reconfirmation of that lack of confidence.
 
  • #3,400
Astronuc said:
Here is another good overview of the Fukushima event.
www.vgb.org/vgbmultimedia/News/Fukushimav15VGB.pdf

If I've understood page 20 of the linked report correctly it suggests that the majority of the zircaloy tubing in reactors 1 & 3 has oxidised and no longer retains structural integrity.

"Estimated Hydrogen production (Recalculation)
- Service floor volume: ≈ 8000 m3
- Within flammable range: ≈ 320 kg H2
=> Extent of core oxidation: ≈ 60 to 70 %"

The calculation is based on the lower flammability limit of hydrogen in air (4%). I could do the calculation myself if I knew the mass of zircaloy in RPVs 1 & 3.

(I think they've made an error. The density of H2 at STP is about 0.09 kg/m3, so a 4% concentration in 8000 m3 is only about 29 kg.)
 
  • #3,401
tsutsuji said:
...
I am also wondering whether the following scenario in NUREG-1150 is not more or less similar with what happened at Fukushima :



This sounds close enough to the "D/G Inoperable due to Tsunami flood" analysis on page 12 of http://www.nisa.meti.go.jp/english/files/en20110406-1-1.pdf and professor Yoshiaki Oka's analysis :



Some mysterious Mitsubishi emplyee, Haruki, is also being quoted as saying :



Erick Krock, who is probably not a nuclear specialist concludes :



But you would still need to cool these higher elevated Diesel Generators with a distinct and secure cooling system.

The relevance of NUREG-1150 (albeit with a link to part 2 : http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1150/v1/sr1150v1part-2.pdf ) was suggested in http://www.bloomberg.co.jp/apps/news?pid=90920000&sid=aQkgwhzUb4pI (18 March 2011)

The following part of NUREG-1150 is also being quoted by Joseph E. Shepherd :

And to think that they had a lake up beyond those hills that could have been used for cooling water for Diesels in an emergency.
 
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  • #3,402
Joe Neubarth said:
And to think that they had a lake up beyond those hills that could have been used for cooling water for Diesels in an emergency.

How big are the backup diesels they use in these plants? We install generators up to 3MW with fan-driven air-cooled radiators.
 
  • #3,403
Actually there's a lake just outside the perimiter fence of the site, about 1km from the reactor buildings themselves!.
 
  • #3,404
artax said:
Actually there's a lake just outside the perimiter fence of the site, about 1km from the reactor buildings themselves!.

Why would we assume 1km of cooling pipe would survive an earthquake?
 
  • #3,405
No, they could have used that water for emergency cooling of the reactors AFTER the damage instead of sea water. Sorru... hadn't followed the previous threads very comprehensively!
Some images just released... mostly terrible resolution!
http://cryptome.org/eyeball/daiichi-npp6/daiichi-photos6.htm
 
  • #3,406
WhoWee said:
Why would we assume 1km of cooling pipe would survive an earthquake?
As long as a fault line does not cross the channel to the lake, there should have been no problem. The actual earthquake site was a long distance away.
 
  • #3,407
I don't think it has been posted yet, especially considering they are useless..
http://www.meti.go.jp/press/2011/04/20110411007/20110411007-6.pdf
that's some of the famous T Hawk picture .. but the dumb down version they release is ...

edit .. artax posted faster... so they got posted b4...
 
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  • #3,408
http://www.meti.go.jp/press/2011/04/20110411007/20110411007-5.pdf

ok this has not (bellow the legend of the squared items)
-Transit vehicles (unmanned)
-Camera car (unattended six in total)
-Cables
-Debris collection area
-Remote control range of movement of heavy equipment
-Movement range Kuroradanpu
 
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  • #3,409
It just shows they're hiding stuff, they must have collected really good images of inside the buildings by now. I mean to make decisions on what to do next you would get much better resolution, and why doesn't the drone get any closer?... is the radiation THAT high they're worried about electronics damage?
 
  • #3,410
any word on restoring power to control centers? or are they given up on this?
 
  • #3,411
Joe Neubarth said:
As long as a fault line does not cross the channel to the lake, there should have been no problem. The actual earthquake site was a long distance away.

Given the level of second-guessing as to the design of these facilities - "should have been" doesn't seem to meet the level of future expectations?
 
  • #3,412
WhoWee said:
Given the level of second-guessing as to the design of these facilities - "should have been" doesn't seem to meet the level of future expectations?
Should have been, because the poster (ME) is not a geologist. I don't know if there is even a little fault line between the lake and the bluffs where the diesels should have been built in the original design. It seems totally impossible to me that any design engineer would have put the diesel generators down at sea level if he knew that they were to be used in case of a loss of electricity accident (which almost certainly would have been caused by an earthquake and tsunami.) Engineers when millions of lives are at stake are supposed to plan for a worst case scenario. I know there are accounts of Tsunamis that were as large as the one that hit Fukushima. Something was very wrong with the planning, and in forty years nobody took corrective measures. The degree of culpability for this horrific mess is going to be massive considering the time span.
 
  • #3,413
|Fred said:
any word on restoring power to control centers? or are they given up on this?

Right now, the control centers are not a desirable place to spend long periods of time.
 
  • #3,414
Joe Neubarth said:
Should have been, because the poster (ME) is not a geologist. I don't know if there is even a little fault line between the lake and the bluffs where the diesels should have been built in the original design. It seems totally impossible to me that any design engineer would have put the diesel generators down at sea level if he knew that they were to be used in case of a loss of electricity accident (which almost certainly would have been caused by an earthquake and tsunami.) Engineers when millions of lives are at stake are supposed to plan for a worst case scenario. I know there are accounts of Tsunamis that were as large as the one that hit Fukushima. Something was very wrong with the planning, and in forty years nobody took corrective measures. The degree of culpability for this horrific mess is going to be massive considering the time span.

I'm not a geologist either, but when considering the island itself moved about 8' - a 1km run of pipe just doesn't seem like the answer?
 
  • #3,415
Will silt fences really make a difference in reducing the Iodine and Cesium contamination of the ocean, or is this just good PR?

My chemistry is limited to what I read in wikipedia, and to my limited understanding the Iodine and Cesium will be in some form of a salt and a such dissolved in the water and thus pass straight through the silt fences. Could a more knowledgeable contributer please correct me.


[PLAIN]http://k.min.us/ikouag.JPG
[PLAIN]http://k.min.us/iksAqg.JPG
 
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  • #3,416
Michio Kaku (26 March 2011) on plant design :

They should have had a tsunami wall much greater than 15 ft ; They should not have put the generators in the basement.
6:25 - 6:37 at
 
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  • #3,417
INES 7 on the way ?
"NEWS ADVISORY: Japan eyes raising level of nuke crisis to most severe"
 
  • #3,418
So soon we reach to level 8
 
  • #3,419
Joe Neubarth said:
Yet, we have San Onofre in San Diego County which is sitting east of San Clemente island. There is an earthquake fault running just up the eastern coast line of San Clemente with a very large and sharp depression off shore and an unstable island above. Somehow I sincerely doubt that they considered this when they built San Onofre. I am not and have not been impressed with site engineers. Fukushima is just a reconfirmation of that lack of confidence.

I just drove by San Onofre yesterday. It has a 30foot sea wall and you can see what looks like new tertiary off-sight backup power above and slightly inland from the plant itself.

As for fault lines, you can't build in California without being next to a fault line. I'm not sure what island you think is unstable or why.
 
  • #3,420
Demidrol said:
So soon we reach to level 8

There is no level 8 in INES, they will need to create it ;) this could be good idea, before fukushima there wasnt case in INES for >1 reactor disaster in one time...
 

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