Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[SteveElbows]

The same source:

According to TEPCO, based on the records, the Reactors 1, 2 and 3 stopped automatically after the quake, and there was no sign of any physical damage to the reactor. Emergency diesel power generators were working. TEPCO concluded that all the equipments were working normally after the quake and there was no major damage to the plant until the tsunami hit.Well, this last bit is highly questionable. Other reports say that the emergency core cooling system stopped working even before the tsunami hit, and that a very high level of radiation was detected at the reactor building of Reactor 1 on the night of March 11, too high unless the RPV and the Containment Vessel were breached by the earthquake, not by tsunami.

http://ex-skf.blogspot.com/2011/05/asahi-shinbun-core-meltdown-in-reactors.html

We should be able to learn more about the using the data that was released today, including the hard to grasp documentation that I have been describing as a treasure trove here today.

http://www.tepco.co.jp/nu/fukushima-np/index10-j.html

Ive been working backwards through that page seeing what the documents are. In addition to the useful sections I mentioned earlier, section 3 contains a number of raw logs and a lot of detail about the control rods and their status once the earthquake hit.

 

[zapperzero]

not showing off here, just trying to help non-boiler folks get a handle on what it means.

Thanks, I don't see it as showing off but rather as good, useful info. Just one question, if you have the time to answer:

Say you're running a 700 MW(e) plant. 400 tons of sea water (that is, about a swimming pool's worth, I liked your comparison a lot) suddenly show up in the condenser, some of it even makes it into the boiler before you realize something's wrong.

Is this a "corroded pipe bust a leak" or a "turbine blade sliced open the condenser" kind of event?

 

[Uagrepus]

This helicopterfootage shows (at 5:30) some piping next to reactor 4 that has been ruptured and seems to be coming from the exhaust stack between units 3 and 4.
http://img716.imageshack.us/img716/8693/reactor4piping2.jpg

I don't think, it is ruptured. Just a matter of perspective:

 

[~kujala~]

Did you notice this one?

The company says it took steps to make the waste facility more watertight, and received approval from the government's Nuclear and Industrial Safety Agency.

http://www3.nhk.or.jp/daily/english/16_25.html

If a building is designed to be watertight you cannot make it any "more" watertight. It's either watertight or not. If there is even one leakage path, it's not a watertight building. And because this is a nuclear plant the general assumption is also that the watertight systems are still working if a building was designed to be watertight.

I am afraid that the waste facility was not designed to be watertight and now they are trying to fix this design flaw. Or alternatively, it has lost its watertight capabilities during years and now they are trying to fix leaks. Either way, now it seems that the waste facility is a potential leak source into the ground/groundwater because even if they try to fix it they might fail as they have to do it in a short time frame, I presume.

 

[etudiant]

Did you notice this one?


http://www3.nhk.or.jp/daily/english/16_25.html

If a building is designed to be watertight you cannot make it any "more" watertight. It's either watertight or not. If there is even one leakage path, it's not a watertight building. And because this is a nuclear plant the general assumption is also that the watertight systems are still working if a building was designed to be watertight.

I am afraid that the waste facility was not designed to be watertight and now they are trying to fix this design flaw. Or alternatively, it has lost its watertight cabapilities during years and now they are trying to fix leaks. Either way, now it seems that the waste facility is a potential leak source into the ground/groundwater because even if they try to fix it they might fail as they have to do it in a short time frame, I presume.

Maybe the earthquake damaged the plant enough for it to leak?
It just seems implausible that anyone would design a leaky nuclear waste water treatment plant.

 

[razzz]

It was a 9.0 earthquake, can't be to surprised something broke or got loose. Then there is the tsunami where the sea reportedly receded leaving 300 feet of the sea floor exposed before the tsunami arrived. No intake for the water cooling system during that period and a gusher heading into any unprotected channels and pipes leading back into the plant during the peak of the tsunami.

 

[zapperzero]

(off topic)
What else here is yellow ( not yellowcake I presume ?)

Going further off topic. Rock wool is yellow. It is found in roofs, for purposes of insulation.

I cannot imagine a kind of explosion that would smash that cap into tiny little pieces. Not even a nuke could do that, the cap would vaporize first.

Small explosions might rock it a bit off its seat or maybe bust a hole clean through if there was something small and heavy inside that got propelled real fast by a high speed blast (another thing I don't believe in, because the horrible amount of damage suggests low speed, long pulse, plenty of time for concrete to realize what's happening and start to crack).

Big explosions could make it fly off as a whole or maybe (maybe!) crack at a seam and open up like a can of sardines, IF it has any seams, IF it was too well anchored.

I do not believe in many small chunks of high-grade steel, all of them falling painted side up and not scorched/blackened by soot in the aftermath of the explosion that made them part company.

 

[SteveElbows]

Here is TEPCOs english description of the document treasure trove:

http://www.tepco.co.jp/en/press/corp-com/release/11051610-e.html

So they have not translated the data to english yet (im not surprised given the form it takes), but at least we have more context for why this data is suddenly with us. It is the report containing data that NISA demanded TEPCO hand over about various parameters of the plant at the time of the quake and the hours immediately afterwards, TEPCO finally delivered it.

I still would not be surprised if this is what that newspaper got their hands on very recently.

 

[bill-green]

First post, not a journo or troll, being an engineer just interested, please bear with me I have one question
I remember that in the Chernobyl incident that they tunnelled under the reactor core. Initially to install a large air conditioning unit. Then decided to fill it with concrete.To stop the corium core hitting water below which would have caused a very large explosion. How do this relate to this incident ?
God bless the miners that dug that "room"
tia

 

[~kujala~]

Maybe the earthquake damaged the plant enough for it to leak?
It just seems implausible that anyone would design a leaky nuclear waste water treatment plant.

Sorry, I forgot that damn quake!
(It is the third alternative, of course.)

 

[PietKuip]

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110516e12.pdf

After the tsunami, the paper records of reactor pressures stopped in units 1 and 2.

"We assume that because of Tsunami, electricity for instruments was lost, the pressure transmitter’s signal became abnormal and the chart stopped."

So immediately after loss of power, the operators were blind? How can crucial equipment be allwed to be so dependent on mains power?

Unit 3 has data of the water level after the tsunami. Within about an hour, it goes of scale. After two hours it comes back, and oscillates a few times with a huge amplitude. Difficult to understand what is going on there.

 

[PietKuip]

Here are 60 pages of data plots: http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_8_Parameter_graph.pdf

Page 30 shows CAMS readings from the Unit 2 suppression chamber (B) from the middle of April till now. I cannot really pinpoint dates, but there are large peaks (up to 160 Sv/h) with a valley of about 40 Sv/h.

There seems to be a correlation with drywell temperature RPV (C):
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/plot-un3-full.png

Is this where the corium is, in the middle of the torus? Is it going critical some weeks?

 

[MadderDoc]

None of the CAMS readings seem to do anything different at that point on the 21st at reactor 3, so I am still not really sure what to think. When reading the wikipedia entry it sounds like they blamed the fuel pool for the smoke on the 21st, and it was the darker smoke of the 23rd that caused more reactor suspicion at the time?

Of the March 23 smoke event there seems no trace of in the data.

Using the tabular data reveals that the high pressure event on 21 March was already early during the night hours, so the smoke event we have seen on daylight photos from that date might well also not have anything to with each other.

Concomitant with the 21 March high pressure measured by the RPV A sensor, the B sensor went the other way and measured a drop to atmospheric pressure, also unstable water level was registered around at that time. The event was followed by the CVs dropping to atmospheric pressure during the morning, it has stayed at atmospheric ever since The wet-well pressure appears to have been critically high, about 0.5 MPa, in the evening on March 20 before the high pressure event past midnight on March 21. Pressure data for the wet-well is absent, from late March 20 until early March 24.

I've no idea what went on, but there seems to me too many indications of changes going on concurrently to dismiss it easily as just a data fluke.

 

[razzz]

From the http://ex-skf.blogspot.com/2011/05/asahi-shinbun-core-meltdown-in-reactors.html" Posted by arevamirpal::laprimavera, his interpretations...

The data disclosed on May 16 was the data right after the earthquake on March 11. It took TEPCO some time to retrieve the data from the central control room of the plant because of the long period of power outage and the radioactive materials on the recorded printout. The data in 4 large binders includes graphs on the printout and operation diaries kept for each shift.

With pin-feed printouts and notes caught in the fallout which had to be de-contaminated and not being sent electronically using battery backup to an offsite network server via satellite, kinda funny...okay maybe not.

 

[ernal_student]

Did you notice this one?


http://www3.nhk.or.jp/daily/english/16_25.html

If a building is designed to be watertight you cannot make it any "more" watertight. It's either watertight or not.

I have noticed that sometimes discussion focuses on one word. Although that may be very important, I would like to suggest that in such cases you need to consult the original text!

I am not a native speaker of English, but even to me it looks like the translations you find in our media are not provided by native speakers of English. Am I mistaken? Do you find the English reports from Kyoudou News and NHK are proper sounding English?

For exact analysis you need at least a translator who is a native speaker and who can correct errors in the translation. This is just my opinion.

 

[MadderDoc]

This huge piece comes probably from N°4 "1st floor visible" (actually it is i think second floor) broken wall.

Look at this picture:

http://www.netimago.com/image_200874.html

The hole just behind the big chunk on the rightmost side of the wall is IMHO where it comes from.

Looking at how thick this piece of concrete is, we can imagine the force of the explosion at this place to break such a piece in a place which seems a little far from the attic SFPs where H2 "could" have originated (the only place in fact where there was fuel). Did the explosion at N°4 originated in the lowest floors in this area? The only place where the roof has disappeared is above this place and the north wall is heavily dislocated.

I think perhaps this chunk might be from the top level of panels. From the low position it would seem a big ventilator thing have miraculously escaped the collision. Against this thought speaks the apparent low grade damage to the pipe on which the chunk fell.

The more I look at unit 4, the more an impression forms of a building thoroughly filled with a mixture of hydrogen and air enough to cause a widespread deflagration, if not an explosion.

I've attached a frame from the THawk trip along the turbine buildings showing the chunk.

 

[bytepirate]

i have played a little bit with the new data.
no big conclusions yet (except that the CAMS data of #1 was definitely invalid after that 100Sv peak in early april)

but maybe it's a starting point for someone else (i have converted the date to hours after scram and the exponential [text]values of the CAMS data into real numbers. bonustrack: double logarithmic diagram time/CAMS ;-))

as this forum does not allow openoffice uploads, and no excel larger than 100kb, i have put them on my server:

http://bytepirates.com/fuku/unit1data.ods
http://bytepirates.com/fuku/unit2data.ods
http://bytepirates.com/fuku/unit3data.ods

or excel, if you need it

http://bytepirates.com/fuku/unit1data.xls
http://bytepirates.com/fuku/unit2data.xls
http://bytepirates.com/fuku/unit3data.xls

 

[yakiniku]

Am I mistaken? Do you find the English reports from Kyoudou News and NHK are proper sounding English?

For exact analysis you need at least a translator who is a native speaker and who can correct errors in the translation. This is just my opinion.

The English in the news from Kyodo and NHK is proper English. Perhaps a little bit awkward but difficulties in keeping literality of meaning and tone between the two languages is obvious.

Very interesting but OT - semiotics:

http://www.amazon.com/dp/0297830015/?tag=pfamazon01-20

Note: I am native English with so-so Japanese.

 

[rowmag]

I have noticed that sometimes discussion focuses on one word. Although that may be very important, I would like to suggest that in such cases you need to consult the original text!

I agree. Here is the original article:

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110516/1655_3gouki.html

wherein the phrase used is "水漏れ対策," or "water leak counter-measures" -- i.e., they fixed a leak (or some leaks).

I am not a native speaker of English, but even to me it looks like the translations you find in our media are not provided by native speakers of English. Am I mistaken? Do you find the English reports from Kyoudou News and NHK are proper sounding English?

NHK's written English is pretty good, actually. In the referenced article only one error jumped out at me: "there is about 22,000 tons of [...] water" instead of "there are about 22,000 tons of [...] water." But that is an error a native speaker might make, if distracted by "water" being an uncountable noun.

For exact analysis you need at least a translator who is a native speaker and who can correct errors in the translation. This is just my opinion.

Yes, that is also my opinion. Some organizations use non-native translators, and then have native English speakers simply correct the grammar. But that will not catch translation errors, unless the native English speaker can check against the original Japanese (in which case they might as well have done the translating in the first place). The result is then polished-sounding, but incorrect. Which may be more dangerous than an obviously flawed translation, which should at least alert readers not to over-interpret.

(I don't know what NHK's policy is.)

 

[MadderDoc]

<..> could it be possible that they were doing some maintenance on the vent at this place, so the pipe was disconnected at this point when explosion happened?

A photo taken right after the tsunami shows the pipe connected and in fine shape, one can also glean from the photo how it was then supported, see attachment.

Of interest, on later pictures, we can see that the curved tubing that was intact after the explosion in now... bent towards the ground!

Well seen. It has also now gotten a new interim support.
Edit: on further consideration, this is not a new support, it is the original support now just bent with the pipe. The existence of the support could be why this part stands back unscathed while the connecting pipes to the reactor building were snapped off and crunched on the ground by falling debris.

See it:
http://www.netimago.com/image_200769.html

Do you think they bent it purposely in between? Why? For the crane to go maybe?

It does not look to like an intentional damage, and it would also not make much sense for anyone to bother making it. A possibility is the fallen concrete structure from the service floor SW corner, it might have hit the pipe. The structure was aloft after the explosion, but in this photo series it is up there no more.

 

[ernal_student]

I agree. Here is the original article:

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110516/1655_3gouki.html

wherein the phrase used is "水漏れ対策," or "water leak counter-measures" -- i.e., they fixed a leak (or some leaks).

The sentence where this appears could also mean something like "... TEPCO performed water leak countermeasures at a different building" - which, from what is written before that, could mean that the current facility is overburdened and they need to prepare another place.
In any case, whether it means fixing leaks, in my opinion "more watertight" is not a good translation. It is also logically wrong (someone already said that).

Even if you think the translations are good English (something I can probably not judge), I think we should look at the original text when there is some strange sounding information.

Thank you also for correcting my impression.

 

[mikefj40]

The NRC is winding things down in Japan...

"The United States Nuclear Regulatory Commission said on Monday that its 24-hour operations center had stopped monitoring the nuclear reactors at the Fukushima Daiichi plant because the situation there had improved. “The conditions at the Japanese reactors are slowly stabilizing,” said William Borchardt, the agency’s chief staff official."

http://www.nytimes.com/2011/05/17/world/asia/17briefs-Fukushima.html?_r=1

Sayonara!

 

[SteveElbows]

Here is one of the stories that emerges with the early data:

http://www3.nhk.or.jp/daily/english/17_04.html

An emergency condenser system at the Number 1 reactor functioned for less than 10 minutes after the earthquake. The failure lasted for 3 hours.

The utility suspects that workers manually shut down the system as pressure inside the reactor became so low that they were afraid of damage.

 

[pdObq]

Looking at that webpage, it says "built on solid bedrock" explicitly only for Daiichi. So, should I interpret that as Daini and Kashiwazaki Kariwa are not?

I tried to locate a Japanese page with the related information on the TEPCO website, but many pages have been replaced by a note concerning the emergency since the earthquake, and I have been unable to find such information in Japanese. I would not argue about the English text until you have seen the Japanese original. That is just my opinion.

Yes, I fully agree with you. My comment above was intended to be somewhat ironical.

 

[MadderDoc]

Find attached photos from two angles of a cylindrical oject lying leaned to the roof wall of turbine building 3. Seen from the THawk angle, one can well interpret the object as being connected to the piping there, i.e part of the original installation, albeit somewhat damaged. However, seen from the west in a zoom from one of the herostratic high resolution photos, it can be seen that it is not mounted, but has crashed on top of the original pipe. It has not been possible for me to find any satellite photo from before the unit3 explosion showing this object. So, I am led to believe that this object could be one of the ballistic objects. I have no idea what it could be, and where it sat in the building before the explosion. No high hopes that anybody can identify it, there are few clues except shape and a peculiar coat it appears to have been lined with.

 

[pdObq]

I have used this link to check the Japanese text.

It is not a document from TEPCO (maybe nobody has ever claimed that it was, but I want to mention this just to make sure there are no misunderstandings).

The text is a critical (no, condemning) description of how TEPCO, 40 years ago, after realizing that the weak clay and sandstone in the upper 25m of the building site would have made it necessary to drive foundations as far down as the layer of relatively firm mudstone (泥岩層) below, removed the top portion of the building site, which made for easier access to cooling water and loading facilities for fuel easier. The current design is based on the assumption that a tsunami would at most have a height of 5.7m. The included drawing is self-explanatory.

Respectfully submitted for your consideration, but it seems that none of this is new information or a revelation.

Thank you very much for looking at the Japanese original and for your summary of its contents. Judging from other posts following yours, it seem to be useful additional information, in general.

 

[rowmag]

The sentence where this appears could also mean something like "... TEPCO performed water leak countermeasures at a different building" - which, from what is written before that, could mean that the current facility is overburdened and they need to prepare another place. In any case, whether it means fixing leaks, in my opinion "more watertight" is not a good translation. It is also logically wrong (someone already said that).

In slightly more detail, I interpreted the original to mean they were fixing another building (than the one used to receive Unit 2's water) within the Centralized Waste Treatment Facility. Which, yes, I guess I can agree is another inaccuracy in the translation that might have contributed to the original poster's complaint.

(For that matter, I suspect it was not a "building" (建物) that they were concerned about, but rather some holding tank or piping within a building. But that may have been an issue with the original terminology -- or my own mis- or over-interpretation. And I issue the caveat that I am not a professional translator.)

Even if you think the translations are good English (something I can probably not judge), I think we should look at the original text when there is some strange sounding information.

Yes, I definitely agree.

 

[pdObq]

Thanks for following up on this issue, NUCENG.

But if terrorists are looking to rival 9/11, dirty bombs or attacks on nuclear plants are much less of a risk than other targets in terms of body counts.

In terms of body counts you might be right, but I guess a successful attack on a NPP would possibly have much greater symbolic value (that doesn't seem the right word, but no better one is coming to mind right now), and due to the general fear of radiation in the public (that also doesn't sound quite right..) it would achieve a much higher degree of "terror", IMHO.

The idea of covers is actually the second physical change suggestion I have seen on this forum that needs to be considered seriously.

I am glad to hear that from someone who has worked in that field. I hope other people in the industry think the same.

OK, the pool shield plugs referenced are interlocking stacked shield blocks that fill in the area where the fuel transfer chute connects to the reactor cavity. They aren't part of the fuel pool per se. They just fill in the area aroung the drywell cap to provide biological shielding during normal operation. Once these plugs are in place the hemispheric shield plugs are added to top off the reactor cavity above the drywell cap up to ffloor level.

So, the reactor well/cavity is separated from the SFP by 4 pool shield plugs + 2 cattle chute shield plugs + 2 gates? Just to make sure I understand you correctly.

 

[pdObq]

So, we now have two facts:
1. having a spent fuel pool on the topmost floor is stupid risky and
2. it is unavoidable in this reactor design.

The conclusion must be that this reactor design is stupid risky. Which means they all should have been scrapped a long time ago or at least not allowed to go on operating past their design lives (but I'm politicizing again, aren't I? At which point does engineering fact become subject to political debate?).

I guess, it's not only the SFPs on the top floor that would make it quite desirable that those kinds of BWRs get retired as quickly as possible, but also the possibility of direct contact between water that was in contact with the fuel with the cooling water coming from the sea or from a river, which that drawing illustrates nicely.

Are there any existing BWR designs that have an additional cooling loop in between the water from the environment and the water/steam from the reactor as a safety feature?

 

[mscharisma]

I have noticed that sometimes discussion focuses on one word. Although that may be very important, I would like to suggest that in such cases you need to consult the original text!

I am not a native speaker of English, but even to me it looks like the translations you find in our media are not provided by native speakers of English. Am I mistaken? Do you find the English reports from Kyoudou News and NHK are proper sounding English?

For exact analysis you need at least a translator who is a native speaker and who can correct errors in the translation. This is just my opinion.

I would say you are correct in your observations. Kyodo's and other Japanese media reports often contain minor grammar issues that suggest that also translation inaccuracies may come into play. Assuming that individual words are the best possible/correct translation may be a fallacy.