Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[swl]

On to food testing when they will 'discover' that a good chunk of radioactivity is in samples hundreds times above limit, which are rare, and aren't stopped effectively by traditional random sampling.

Good point. I live near Fukushima and I'm wondering if there is any way I can test for radiation on my own. My spouse and I are particularly concerned about the health of our young children.

We want to know if we can test food, water, ground surfaces and background radiation on our own, or if we can only trust the government to keep us safe.

 

[AntonL]

To contribute to the mud stone / bed rock discussion, I would imagine the the soil beneath the NPP to be very much the same as that what has been evacuated from the mountan, and judging by the steep unprotected slopes it is a fairly solid geological structure, no soil with bolders but a tending towards a homogeneous structure. So ground water leakage would be slow in cracks and layers within this mud stone massif I presume.

 

[Astronuc]

So there might not be so much value in having a cover on the pool. I doubt the prompt criticality thing is legitimate concern, but I'm no physicist. I'm not sure what a cover is going to do to protect the spent fuel from terrorist attack either.

A cover would only serve to keep foreign material or debris out of the pool. The Mk I containment is really to keep the weather/storms/high winds away from the reactor service floor.

I'm guess the fuel pool is located there out of necessity. They can't get the hot fuel out any other way. The location near the reactor allows refueling without removing the fuel from the boric acid. Otherwise there would be an extended shutdown while waiting for the spent fuel to 'cool down.'

Irradiated fuel must be moved under water in order to protect the workers from radation. That is the main reason for the location of the spent fuel pool. The Mk III containment design has the SFP in a separate building and an improved containment structure.

The spent fuel pools are normally cooled. They must accommodate a full core offload which would have significant decay heat compared to fuel which has been permanently discharged.

 

[AntonL]

If you run a windows XP operating system you can simulate and watch the plant parameters unfolding. Download for free PCTRAN pre-configured for Fukushima, or other reactor types, from this site http://www.microsimtech.com/ (It does not work for Vista and above!)

(I think Tepco might have used this for their latest unit 1 meltdown simulation.)

Hers are the studies for unit 1 and 3

http://www.microsimtech.com/Fukushima.html
http://www.microsimtech.com/downloads/Fuku3.htm

and SFP-4 simulation
http://www.microsimtech.com/downloads/Fuku4.html
however it has a mistake, they assumed the unloaded core to be 15 days old instead of 90+days (unit 4 was shut down end November If my memory serves me right)

 

[default.user]

Good point. I live near Fukushima and I'm wondering if there is any way I can test for radiation on my own. My spouse and I are particularly concerned about the health of our young children.

We want to know if we can test food, water, ground surfaces and background radiation on our own, or if we can only trust the government to keep us safe.

Establishes purchasing groups, and tests everything that counts as food.
We did that in Germany in 1986.
The state will not help.
You need an expensive instrument. This can be paid only in communities.
Draws conclusions from the measurements.

regards from germany and sorry my bad english.

 

[Astronuc]

Good point. I live near Fukushima and I'm wondering if there is any way I can test for radiation on my own. My spouse and I are particularly concerned about the health of our young children.

We want to know if we can test food, water, ground surfaces and background radiation on our own, or if we can only trust the government to keep us safe.

One would need to have a Geiger counter with which one could monitor radioactivity, but it will not indicate which isotopes. To discern which isotopes are present requires a gamma spectrometer, which might be available at some universities. Gamma spectrometers are rather expensive.

http://en.wikipedia.org/wiki/Gamma_spectroscopy

One must also have experience in using a gamma spectrometer including how to set it up, calibrate it and use it. A Na-I type would be sufficient.

 

[default.user]

Maybe this site can bring some help.
Calibrated regularly leave.

http://www.chetan.homepage.t-online.de/sonstig/ram63.htm

 

[rowmag]

Well again, even if this a slightly different subject from the Daichi plant, I have a hard time understanding how seawater can enter so easily (i say "easily" just because it just happened...) into a BWR reactor. But I understand that unlike a PWR, in a BWR there is no real secondary circuit (i mean closed loop), so the steam is condensed into water in the condenser (which is cooled by seawater if my understanding is ok) and goes back into the reactor right?

So any leak between the two (the sea water/the steam or condensed water) can theoretically (and practially in this case) lead to either seawater entering the reactor or contaminated water going back to the sea?

This article from Asahi gives an explanation of how the leakage could be one-way:

http://www.asahi.com/special/10005/NGY201105150003.html

According to the article, the seawater is used to cool steam. So a leak in the barrier would lead to water going into the steam side, but not vice versa. The article includes a speculative leakage path sketch:

They mention that the leak was detected by noticing a rise in saline concentration in the re-condensed water. Then they switched to a different cooling system. No explanation of where the 400 ton estimate came from.

 

[jlduh]

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?).

That's also one of the main subjects the documentary from Adam Curtis cited above is considering:

https://www.physicsforums.com/showpost.php?p=3304718&postcount=7448

 

[etudiant]

Good point. I live near Fukushima and I'm wondering if there is any way I can test for radiation on my own. My spouse and I are particularly concerned about the health of our young children.

We want to know if we can test food, water, ground surfaces and background radiation on our own, or if we can only trust the government to keep us safe.

Default_user has it entirely right.
This is not a problem that is effectively addressed at the individual family level, because even if you check the food with a geiger counter, it gives no insight regarding the outside exposure levels.
This is very much a community issue, particularly as the contamination will be patchy, with local hot spots, something the central government with its need for simple measures cannot easily adapt to.
There may be a role for the central government to help localities to add monitoring equipment, but the real work will have to be done locally, to make sure playgrounds and public sites are adequately clean.
The food supply will inescapably be more radioactive than before. Expect maximum permissible levels to be raised, perhaps substantially. Unless Japan is willing to import much more of its food and to shut down farming in a large part of Honshu, the margin of safety will be less.

 

[jim hardy]

Rowmag

that's a nice graphiic you put up to show how seawater gets in.

I used to work in a power plant.
For non power plant folks,
The box under the turbine where the color fades from pink (steam) to blue(water) is the "Condenser".
Of course that's because it condenses the steam coming out of the turbine back into water so you can pump it back into the boiler, in this case a reactor.
It's a lot of water - in my plant we boiled water at the rate of a residential swimming pool every twenty seconds. (~ten million pounds per hour)
The condenser is a huge sealed shoebox affair box maybe twenty feet square by forty or fifty feet long. Thousands of tubes traverse its length , seawater is pumped through the tubes to carry away the latent heat of condensing steam in the box.

I have been in condensers to pick the seaweed and dead eels out of the tubes - when a lot of them get plugged you got to manually clean 'em out. Stinky job.

Well, if even one of those tubes develops a crack or pinhole it'll let seawater into the shoebox where the steam is condensing.
That shows up almost immediately on analyzers that sample the water on its way back to boiler. There are ion exchange type purifiers in that pipe to take care of a small leak, but it's something you monitor for and shut down right away to fix. Men go in, find the leaky tube and plug it at both ends.

If a turbine throws a blade it can sling it down into the tubes and cut a lot of them and that's a LOT bigger leak than usual.

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

old jim

 

[etudiant]

Rowmag

that's a nice graphiic you put up to show how seawater gets in.

I used to work in a power plant.
For non power plant folks,
The box under the turbine where the color fades from pink (steam) to blue(water) is the "Condenser".
Of course that's because it condenses the steam coming out of the turbine back into water so you can pump it back into the boiler, in this case a reactor.
It's a lot of water - in my plant we boiled water at the rate of a residential swimming pool every twenty seconds. (~ten million pounds per hour)
The condenser is a huge sealed shoebox affair box maybe twenty feet square by forty or fifty feet long. Thousands of tubes traverse its length , seawater is pumped through the tubes to carry away the latent heat of condensing steam in the box.

I have been in condensers to pick the seaweed and dead eels out of the tubes - when a lot of them get plugged you got to manually clean 'em out. Stinky job.

Well, if even one of those tubes develops a crack or pinhole it'll let seawater into the shoebox where the steam is condensing.
That shows up almost immediately on analyzers that sample the water on its way back to boiler. There are ion exchange type purifiers in that pipe to take care of a small leak, but it's something you monitor for and shut down right away to fix. Men go in, find the leaky tube and plug it at both ends.

If a turbine throws a blade it can sling it down into the tubes and cut a lot of them and that's a LOT bigger leak than usual.

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

old jim

Weird, the sea water is just pumped in as is?
Is there a reason that there is no prefilter to keep the eels and seaweed out other than cost?

 

[Jorge Stolfi]

Thanks for finding those. They don't look conclusive to me whether the pipe was damaged or not. I'll keep looking.

IIRC, a previous poster observed that the big venting exhaust pipes of each reactor are separate all the way to the tower tops. So if TEPCO's (?) theory is correct, the "gas treatment system" that supposedly carried hydrogen from #3 to #4 must be something else. Perhaps a system to remove the normal (small) amounts of hydrogen from the steam in the primary cooling loop?

While it seems evident that the explosion happened also in the 4th and perhaps 3rd floor of #4, one should note that the only place in #4 where the main concrete pilars were competely blasted away was on the 5th (service) floor, on the east side of the south wall, right next to the spent-fuel pool. That is rather remarkable because the fuel handling machine and the overhead crane should have protected that corner. Also also the pillars that were snapped away were more closely spaced there and included one extra-wide pillar (which, at lower levels, provides support for the SFP wall and FHM rail).

Finally the bending of the "hockey sticks" on the east side of the FHM could be explained by the latter being briefly lifted by the explosion and hitting the crane rail support on the nearby pillar.

Thus I would wait a little more before buying TEPCO's explanation. The underwater video of the #4 SFP may exclude criticality and an explosion *in* the pool, but in my head it does not yet exclude the SFP as the source of the hydrogen.

If the water level got low enough for the zirconium to get over 800C, but water was restored to the SFP before the zirconium tubes punctured, would the racks or the assembly heads show visible damage?

 

[jim hardy]

"Weird, the sea water is just pumped in as is?
Is there a reason that there is no prefilter to keep the eels and seaweed out other than cost?"

There are screens to act as strainers with maybe 1/2 inch mesh ahead of the big seawater pumps. They get 99% of the stuff. The seaweed in our area was long leafy grass which when it turns sideways oops edit make that endways can get through the screen.

The screens are an endless belt driven by a motor so the stuff comes up, gets washed off them and the screen continues on around on its track.
The doggone eels for some reason want to swim downstream not into the current and a lot of them get around the screens by the track, or squeeze through.
The fish are smarter - they come in near the screens to catch shrimp and then go on their way. Big fish come into eat the little ones - it's an interesting nature show there. And good fishing.

It's a lot of seawater - we had eight seawater pumps each about 175,000 gpm if i remember right.

old jim

 

[elektrownik]

Tepco released many important data: http://www.tepco.co.jp/nu/fukushima-np/

 

[pdObq]

Weird, the sea water is just pumped in as is?
Is there a reason that there is no prefilter to keep the eels and seaweed out other than cost?

Compromise beteen possible flow-rate and size of objects being filtered out?
Also, finer filters would probably have to be replaced more often?

EDIT: Jim was faster... Interesting that the screens are continuously cleaned. I guess that would be a solution for my second point. But probably that gets harder as the filters get finer.

PS: I probably wouldn't go fishing around the outlets...

 

[~kujala~]

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.

Thanks for the source!
http://ziphilia.net/bbs.cgi/economy/1304793715/detailview#A_DEFAULT

Even though mudstone may be "relatively firm" it is still a different thing than bedrock.

First there is (or was) a 25 meter layer of clay and sandstone.
Below that is mudstone.
And below that is bedrock (-46 meters from the current ground level).
http://mdn.mainichi.jp/mdnnews/news/20110427p2g00m0dm091000c.html

As jlduh https://www.physicsforums.com/showpost.php?p=3304601&postcount=7428" TEPCO is lying again when they state in their web-page that "the plants are built on solid bedrock".
http://www.tepco.co.jp/en/challenge/energy/nuclear/plants-e.html

BTW: Does anybody want to translate the texts in this picture from Japanese to English?
http://gbleez.myhome.cx/uploader/src/up7713.jpg
I could make a bigger version of it, with English texts.

 

[Curium]

There is that stem flow from under the top cover of the reactor...

Yeah, seems possible that stuff ejected from the reactor could have gone into the pool when the building blew up, if that is what happened. Question is how much is "high levels of I-131", what does that mean quantitatively? Then extrapolate that amount back two months, equals about 8 half-lives, meaning 'quantity x' to the eighth power was present at the beginning.

The only source about all this 'MOX fuel piece found far away' thing is Gundersen himself. Or at least I could not find anything else, and please inform me if anybody could.

The original source is an NRC document about the Fukushima crisis

http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=1"[A] confidential assessment prepared by the Nuclear Regulatory Commission... The document, which was obtained by The New York Times, provides a more detailed technical assessment than Japanese officials have provided ... The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed. "

So, NY Times says they have this NRC document and quote it verbatim as "up to one mile from the units". Is this "confidential assessment" NRC document now publicly available somewhere? It was either voluntarily provided, or leaked, to NY Times 5 weeks ago, according to the article.

If the 2-kilometer ejection radius is true, in some sense it doesn't matter whether the explosion was a transient criticality or hydrogen or some other detonation. Still a big mess.

 

[artax]

this stuff is still on the TEPCO site too!... guess removing it isn't top of their list of priorities!

1. Measures to prevent unexpected events

* All designs provide margins of safety capable of withstanding even natural disasters.
* Strict quality control at every stage, from design to construction to operation.
* In addition to the elaborate regular inspections that take place every year, interlock and fail-safe systems are incorporated at every turn to prevent erroneous operations or actions.2. Measures to prevent the escalation of unexpected events

* Detection devices to detect abnormalities immediately
* Equipment that automatically and safely shuts the reactor down3. In the extremely unlikely event of an accident
[to prevent release of radioactive substances]

* Emergency Core Cooling System (ECCS)
* Airtight structure of the primary containment vessel and the reactor buildingAnti-Earthquake Measures
img01

Designed for the Largest Conceivable Earthquake
Before constructing a nuclear power plant, the site is carefully studied for previous earthquake records and geological features. This study establishes that there is no active fault under the site. Then, the building, the equipment, the piping, and other equipment are all designed to withstand the strongest possible earthquake in the area.

Hard-to-Shake Structure
Reactor buildings are built directly on solid bedrock after all soil has been removed. Furthermore, the reinforced concrete walls are far thicker than those used in other buildings. The building itself is a strong dice-like structure. Therefore, in the event of an earthquake, reactor buildings shake far less than an ordinary building.

Automatic Shutdown
Seismic detecting devices in the reactor building are designed to automatically shut the reactor down if they sense an earthquake of level 5 or greater.

 

[jlduh]

I repost here this film in two parts (already posted i think) about the construction of Daichi plant, unfortunately it is in japanese but there are some interesting images of the construction.

Could a japanese language member here view it and try to catch some useful infos from the commentary (don't know if they say something about the preparation on the ground...)?



http://www.youtube.com/watch?v=cTshYXmN1AY&feature=related

There is a part concerning construction of the building starting at around 9'30 (part I) and there is a nice helicopter view at 10'42 over the all plant, showing on the left the concrete foundation of what will become N°2 reactor and turbine buildings besides the N°1.

I attached a capture of the screen at 10'46 (see below)

You can get a bigger image size clicking here:
http://www.netimago.com/image_200707.html

 

[StrangeBeauty]

Tepco released many important data: http://www.tepco.co.jp/nu/fukushima-np/

Thank you elektrownik. Out of those docs, imo here is the biggest problem atm:
http://www.tepco.co.jp/nu/fukushima-np/f1/images/temp_data_3u-j.pdf

Barring all these temp readings being wrong, core material must still be inside the #3 RPV doing something.

 

[zapperzero]

They mention that the leak was detected by noticing a rise in saline concentration in the re-condensed water. Then they switched to a different cooling system. No explanation of where the 400 ton estimate came from.

So, they detected ions that shouldn't have been there, measured concentration, did a quick napkin-based calculation and stated "hmm, we must have taken on an additional 400 tons of seawater for the concentration to be what we found".

They are assuming the best-case scenario. Stuff is coming in, stuff may have been getting out as well.

Where is the coolant mass calculation? They should know to the liter, or at least to the ton, what they put in. It should NOT have been going anywhere. Somewhere, there are volume measurements (for water), pressure and temp readings (for steam plenums, all of which are of known volume, RPV included as the plant is in "cold shutdown" so the water is barely boiling).

Also, the different cooling system must be one of those available for emergency use. The primary cooling has been shut down. The plant is thus in the same situation as Fukushima Dai-ni, post-tsunami, only this time they have chlorine in the RPV. Dai-ni was serious enough to rate a 10 km exclusion zone.

 

[bytepirate]

Tepco released many important data: http://www.tepco.co.jp/nu/fukushima-np/

and many not so interesting as well ;-)

what is new to me, are the documents, that seem to contain *all* data (or at least much more, than i have seen before), that they have for the early days:
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_1u.pdf
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_2u.pdf
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_3u.pdf

have i missed them before, or have they been published only recently?

 

[pdObq]

I repost here this film in two parts (already posted i think) about the construction of Daichi plant, unfortunately it is in japanese but there are some interesting images of the construction.

Could a japanese language member here view it and try to catch some useful infos from the commentary (don't know if they say something about the preparation on the ground...)?



http://www.youtube.com/watch?v=cTshYXmN1AY&feature=related

These have been posted here or at least on houseoffoust a few weeks back. A version with English subtitles has been around for quite a while too (over a month), see the video responses, here for part 1, .

 

[jlduh]

These have been posted here or at least on houseoffoust a few weeks back. A version with English subtitles has been around for quite a while too (over a month), see the video responses, here for part 1, .

Great! Thanks, i didn't see the english subtitled one!

 

[Curium]

[PLAIN]http://galeon.com/saboten7/fukushima3.jpg

Some massive solid debris reaches an apex of more than 200 meters, then falls back to earth. Those parts end up fairly close to the building site.

Something found in the 1000 - 2000 meter range from the building would have to be on a low initial trajectory, or thrown higher than the "mushroom cloud" and maybe carried by wind

 

[MadderDoc]

Thanks for finding those. They don't look conclusive to me whether the pipe was damaged or not. I'll keep looking.

You can arrive at a stronger conclusion by looking at another and later photo which shows where the part of the pipe that came off the wall ended up on the ground. In that way you will have two corroborating pieces of information from this photo you are looking at:

a) the pipe does appear to broken (although some would not like to say so conclusively)
b) the part of the pipe that came off does appear to be lying under it, in the same spot, and angled similarly to how we find that part on later photos.

Added together, this would seem to me sufficient evidence to force us to reject the hypothesis that the pipe remained intact after the unit 3 explosion.

Edit: By 'later photo' I mean any photo showing this area and _taken in the period March 14 through March 20._
We know from the photos that Tepco in order to make access for spraying to the pool had moved the part of the pipe that fell to the ground by March 24th, but had not done so on March 20th.

 

[Rive]

Yeah, seems possible that stuff ejected from the reactor could have gone into the pool when the building blew up, if that is what happened. Question is how much is "high levels of I-131", what does that mean quantitatively? Then extrapolate that amount back two months, equals about 8 half-lives, meaning 'quantity x' to the eighth power was present at the beginning.

With the steam flowing continuously (nighttime pictures) we have a possibly continuous, unpredictable source of I-131 with unknown volume. So with only one sample (I know about only one sample) any deep 'analysis' is just guessing.

The original source is an NRC document about the Fukushima crisis

It'll be this one I think: http://cryptome.org/0003/daiichi-assess.pdf

All it has is:

Fuel pool is heating up but is adequately cooled, and 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 material had to be bulldozed over between Unit 3 and 4. It is also possible the material could have come from Unit 4.)

What's only a 'may have been'.

IMHO it's unlikely that fuel ejected, and found only a mile away and right near the reactor, and nowhere else around the site (it's quite easy to notice ejected fuel by the alarming dosimeters :-) ). So that early 'may have been' actually is a 'not likely' and should not be taken as a fact and used as backup for wild speculations.

PS.: of course: IMO.

 

[Azby]

Good point. I live near Fukushima and I'm wondering if there is any way I can test for radiation on my own. My spouse and I are particularly concerned about the health of our young children.

We want to know if we can test food, water, ground surfaces and background radiation on our own, or if we can only trust the government to keep us safe.

I've heard of a farming community in Nasu, Tochigi Prefecture, that pooled funds to buy 50 geiger counters, and made an agreement with a local lab to use scintillation counters and other more expensive equipment to measure produce, milk, etc.. By all means buy yourself a geiger counter, but please try to organize your community to do the same, and collaborate in order to produce more reliable and meaningful data.

<http://www.safecast.org/> has a program to put geiger counters in the hand of communites that need them.

 

[SteveElbows]

and many not so interesting as well ;-)

what is new to me, are the documents, that seem to contain *all* data (or at least much more, than i have seen before), that they have for the early days:
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_1u.pdf
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_2u.pdf
http://www.tepco.co.jp/nu/fukushima-np/f1/images/syusei_level_pr_data_3u.pdf

have i missed them before, or have they been published only recently?

The original uncorrected ones were published at some point in the past because a user of this forum managed to find cached copies on the internet and posted them here. I was using these originals as the basis for several posts I made yesterday in response to people questioning the timing of events in light of the reactor 1 meltdown news.

The republished data certainly contains a lot more data points, though I have not had time to notice whether there are any really significant new bits of data yet.