Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[|Fred]

idiots..

That's the spirit! they used i-robot http://www.irobot.com/

 

[htf]

But I think there are more factors contributing. First, it has not been 6 but 5 months or less since shutdown. And second, the pool is totally full AND there's probably debris inside, plus it's probably not filled up to the top. So if I double your 24 Bq/cm³ three times (three half times, less then one month) I get ~200 Bq/cm³. And because of the fill status /debris / water height there's probably not 900 billion cm³ water inside, but less.

But what if it is leaking? There was also a lot of steam generated, so a significant fraction of the Iodine could have been released to the atmosphere. They had to fill it many times. You can find good reasons why the 24 Bq/cm^3 are an overestimation.

There is a lot of uncertainty. The observed Iodine could be produced by reactor 4 during normal operation 6 month ago. But the estimated 24 Bq/cm^3 are less convincing then the much higher figures posted by NUCENG. My calculation may be wrong, though.

Anyway - the explanation given by TEPCO gives a deep insight. What are they operating? Windmills?

 

[NUCENG]

Thanks for the tip, serching by title worked fine. From the first ref:



If I read correctly, the report also says that about 35% of the iodine and 25% of the cesium present in the fuel will be released with the coolant leak, in the early stages at least. is this correct?

The second ref (summary) says



If the seawater was treated with sodium borate, it should probably be alkaline. If they used boric acid, I don't know. B(OH)3 seems to be a weak acid; will it be enough to lower the pH below 7? In hot water?

(My greatest achievement as a teenage chemist was distilling ethanol with boric acid to obtain something which I fancied to be ethyl borate. At least, it burned with a nice lemon-green flame, as theory said it would. Presumably that would mean that B(OH)3 does act like an acid? )

The last report you cited seems to have a more limited scope than the first. But its main conclusion, again, seems to be



My conclusion is that, given the unknown/messy chemistry and the unusual physical conditions of the pool, a low concentration of radiogenic iodine in the pool water, a month after the accident, may not imply low level of fuel damage, since an unknown amount may have escaped as I2 or HI with the steam. The level of radioactive cesium in the water may be a better indicator. What does the latter say?

The larger releases come from inital fuel melting in the "early in-vessel" phase of a severe accident. I used only the 5% release for a gap release and that was more than enough to result in the measured concentrations of Cs and I in the fuel pool.

If pH became acidic it would result in increased airborne I-131 on site and downwind. The sample trends don't show that.

In earliers posts I calculated Cs concentrations from the gap release could produce sample concentrations up to 1E6 Bq/cm³. The measured results are very small compared to that in both SFP2 and SFP4.

Yes seawater chemistry and other contaminants in debris dumped into the pool can complicate matters, but this is the best I have found. I am open to a better explanation.

 

[bytepirate]

about unit #4 explosion: "IF" there would be fuel in core then this explosion wouldn't be simpler to explain ?

if we consider the RPV and the SFP (more or less) connected, and i think we have to, that would not make a difference, imho.

one might make up a scenario, where a core is in the RPV. RPV and SFP are not connected. RPV water boils off - explosion - water from the SFP floods the RPV...

but this is of the same likeliness as this: https://www.physicsforums.com/showpost.php?p=3245053&postcount=3653

not likely at all.

 

[cphoenix]

I agree with everything you say but if you eliminate hydrogen from SFP4 what is left? However improbable, and to date unproveable, it had to come from an external explosion. The initial report of the explosion talked of "an explosion inside the facility" and then they found damage to unit 4. It doesn't sound to me like they knew for certain that the explosion was inside unit 4. Your guess is as good as mine.

Stagnant, near-boiling-hot water at the bottom of the pool would contain 24 kg TNT equivalent per cubic meter. 125 C, 4 J/gC, 1E6 g/m^3. Do the arithmetic. 1E8 J = 24 kg TNT.

There are at least three ways that convection could be stopped, and hot water accumulate:

1) Rack falls over.
2) Something flat falls on rack, covers top.
3) Rack knocked off supports, sitting on pool bottom.

How many cubic meters of water could be trapped? 1E2? 1E3? We could easily be talking tons of TNT. Thousands of cubic meters of steam.

If hot water accumulated, then sufficient perturbation (not necessarily much of a disturbance) would create a geyser. Release hundreds, thousands, maybe hundreds of thousands of cubic meters of steam indoors in less than a second... and you lose your roof and walls.

Chris

 

[MiceAndMen]

TCups, you may continue on your puzzle hunt, which has often been interesting -- but I'm just trying to keep you from wasting time on bad information. Yes, I'm suggesting fakery/fraud to gain viewers. It was obvious to me from the first time I heard it that was concocted since I've concocted such things myself for various purposes (e.g. foley work). Not only did I think this was concocted, but it was badly done - an obvious fake for the reasons I listed above. An actual, large explosion at that distance sounds nothing like that track. If a real soundtrack for the explosion became available why wouldn't the more reputable news organizations cover that? The bottom line, as an investigator, you need to prove your source is legitimate and that has not been done.

We need to get some information from the horse's mouth, so to speak. Whose camera recorded the explosion? Where was it located? Did it also record audio? If the released video shown on TV - I would heavily, heavily discount anything found on YouTube - had an audio track, where was the microphone that recorded the audio?

As bad as the press is in the US, I'm sure all those questions would have been asked and answered already if a reactor building exploded here. Maybe they are asking those questions in Japan and we're just not aware of it due to the language barrier that keeps us from really following the Japanese news coverage, blogs and other websites there.

EDIT:

Original video is from NTV/NNN , I was not able to find any Japanese version with a sound track. It does not imply that there was not one. I recall that those picture were taken from a helicopter, but can not source it.

Thanks, Fred. I replied above before seeing your post. It's a start. I, too, remember hearing initially that a helicopter recorded the video, but I don't remember where I heard that.

 

[Dmytry]

Stagnant, near-boiling-hot water at the bottom of the pool would contain 24 kg TNT equivalent per cubic meter. 125 C, 4 J/gC, 1E6 g/m^3. Do the arithmetic. 1E8 J = 24 kg TNT.

There are at least three ways that convection could be stopped, and hot water accumulate:

1) Rack falls over.
2) Something flat falls on rack, covers top.
3) Rack knocked off supports, sitting on pool bottom.

How many cubic meters of water could be trapped? 1E2? 1E3? We could easily be talking tons of TNT. Thousands of cubic meters of steam.

If hot water accumulated, then sufficient perturbation (not necessarily much of a disturbance) would create a geyser. Release hundreds, thousands, maybe hundreds of thousands of cubic meters of steam indoors in less than a second... and you lose your roof and walls.

Chris

scary. Now i think your hypothesis is VERY plausible.

 

[cphoenix]

looking at the sources (digitalglobe pics, drone video) already posted, i can not imagine any outside source for the damage in #4.

I agree.

what exploded in #4?

(trimmed by cphoenix)

steam explosion?
i have not found any reference to this possible risk anywhere in the literature. were all the engineers that did the risk analysis wrong? rather not -> quite unlikely

Thanks for doing the literature search.

I disagree that "they didn't think of it ahead of time" means "it's likely impossible." Very simple mechanics and arithmetic says it is possible. Human nature says it's easy to miss.

I knew about water under pressure - A couple of years ago, I happened to heat a glass of water under oil in the microwave, and I saw it blow liquid all over the place quite suddenly. And yet, knowing that the building 4 explosion happened with no obvious source, it took me a week and several wrong guesses to think of the steam explosion mechanism.

When I did the arithmetic, I was shocked at the amount of energy that could be held in the water.

And then, despite knowing how geysers work, I didn't think of geysers until someone else used the word several days later.

And even now, lots of people on the list dismiss the idea out of hand, for no better reason than "I don't see what would trap the water." After a 9.0 earthquake!

Bottom line, it would have required creativity and luck to think of this mechanism at all. Once they thought of it, it would be pretty easy to verify.

Can we agree that, if they had thought of it, they would at least have said, "If a metal plate falls into the pool and settles on top of the racks, get it off of there damn quick before the water has time to heat up even a few degrees." To me, the absence of that caution indicates that they did not consider the geyser effect.

So take your pick:
1) Geysers don't happen.
2) They didn't think of geysers.
3) They decided there was no way to set up the required conditions - which means, no way to block convection.

I'm going with "2," but I could also go with "3, and they were wrong." It's way too early to say "3, and they were right."

Chris

 

[TCups]

TCups, you may continue on your puzzle hunt, which has often been interesting -- but I'm just trying to keep you from wasting time on bad information. Yes, I'm suggesting fakery/fraud to gain viewers. It was obvious to me from the first time I heard it that was concocted since I've concocted such things myself for various purposes (e.g. foley work). Not only did I think this was concocted, but it was badly done - an obvious fake for the reasons I listed above. An actual, large explosion at that distance sounds nothing like that track. If a real soundtrack for the explosion became available why wouldn't the more reputable news organizations cover that? The bottom line, as an investigator, you need to prove your source is legitimate and that has not been done.

Heck, SB, this is the internet, and I am not writing a PhD dissertation. We are all just "out there" on the net, trying to figure out what has happened, digging for whatever information is available -- videos, pictures, and links -- just fanning our mental puds, so to speak, and trying to figure out what has happened. I didn't weight the audio track as "key" to any of my free wheeling concoctions about what may have happened at Fukushima, but neither did I dismiss it as absolute fraud, particularly after getting what I took to be a pretty "sound" opinion from another of my online friends here at this thread. I confess that my talents (which may be too strong a word), such as they are, are more in tune to the visual than the audio puzzle. And I do love a good puzzle.

 

[M. Bachmeier]

We need to get some information from the horse's mouth, so to speak. Whose camera recorded the explosion? Where was it located? Did it also record audio? If the released video shown on TV - I would heavily, heavily discount anything found on YouTube - had an audio track, where was the microphone that recorded the audio?

As bad as the press is in the US, I'm sure all those questions would have been asked and answered already if a reactor building exploded here. Maybe they are asking those questions in Japan and we're just not aware of it due to the language barrier that keeps us from really following the Japanese news coverage, blogs and other websites there.

I strongly agree with you. Even if someone is holding on to a larger video for resale, a few details would be helpful. Camera distance. Audio source. Video length. Audio length if different from camera. Distance of audio source if different from camera.

Contrary to previous opinions, it would not be that easy to fake the audio for the video in question, not with the kind of visual synchronization I found.

Note: if the audio was a fake, it would have been the same length as the video... all part of post processing... *video* 13.25 sec. approx. *audio* 12.77 sec. ?

 

[TCups]

That's the spirit! they used i-robot http://www.irobot.com/

domo arigato, Mr. Roboto.

 

[NUCENG]

I think there's the problem. 33% is multiply by 0.33, not divide. Or divide by 3.


But I'm not sure as to what those 33% efficiency apply to in the calculations.


Edit: Screw that - you're right... ^^;

33% = the 760 MWe, 100% = total MWt

Hm, I also get your results...


But I think there are more factors contributing. First, it has not been 6 but 5 months or less since shutdown. And second, the pool is totally full AND there's probably debris inside, plus it's probably not filled up to the top. So if I double your 24 Bq/cm³ three times (three half times, less then one month) I get ~200 Bq/cm³. And because of the fill status /debris / water height there's probably not 900 billion cm³ water inside, but less.

Yep there was an error in my spreadsheet. Thanks for the second check. The source term is expressed in Ci per MW thermal. To produce 760 MW electric the reactor must produce abut 2280 MW thermal for the 33% efficiency. I am now coming up with about 11 Bq/cm³. with 6 months of decay. Backing that up to 5 months would give about 176 Bq/cm³. That is close to the value of 220 Bq/cm³ found in SFP4.

 

[clancy688]

domo arigato, Mr. Roboto.

Domo arigatoooo, Mr Robotooo

(sry, but you're responsible for having this song stuck in my head again...)NUCENG, did you read my notification? :)

 

[M. Bachmeier]

domo arigato, Mr. Roboto.

You forgot the link...

 

[Dmytry]

I disagree that "they didn't think of it ahead of time" means "it's likely impossible." Very simple mechanics and arithmetic says it is possible.

Strongly agreed. Even if there's some circulation, there has to be a lot of circulation to avoid geyser effect. I was sceptical but now I am convinced that your hypothesis is plausible. I still doubt it's the full picture, but it can happen, and if we're to discuss criticality in SPF we need to also think of geyser effect.

 

[TCups]

Speaking of fact checking and posting the correct references

The original video from the BBC without sound that I first viewed:


This is the explosion at Unit 1, StrangeBeatuy


The same video from Sky News without sound:


...and this is the explosion at Unit 3 -- hardly the same video, SB


Same video from Japanese TV again, without sound:


... and this is the explosion at Unit 3

The oztvwatcher version (who's that?) with sound:


...ah ha! Now you have it. The video and audio from the explosion at Bldg 3


Another video from Indian TV (?guessing here) with completely different sound:


Yes, indeed, the explosion at Bldg 1 does have a completely different sound than the explosion at Bldg 3! Amazing. I had probably missed that.

Which ones have been faked? They can't all be the original.

TCups, you may continue on your puzzle hunt, which has often been interesting -- but I'm just trying to keep you from wasting time on bad information. Yes, I'm suggesting fakery/fraud to gain viewers. It was obvious to me from the first time I heard it that was concocted since I've concocted such things myself for various purposes (e.g. foley work). Not only did I think this was concocted, but it was badly done - an obvious fake for the reasons I listed above. An actual, large explosion at that distance sounds nothing like that track. If a real soundtrack for the explosion became available why wouldn't the more reputable news organizations cover that? The bottom line, as an investigator, you need to prove your source is legitimate and that has not been done.

 

[StrangeBeauty]

Speaking of fact checking and posting the correct references

I sincerely apologize to the members for inadvertently including two videos of the #1 explosion.

Interestingly enough, one has sound and the other doesn't. Gee, I wonder how that could have possibly happened just like with the #3 videos...?

That said, my error does nothing to help you prove that the video of the #3 explosion with sound is legitimate. MiceAndMen asked good questions.

 

[Dmytry]

That was over 2 weeks ago - didn't they accept?

Last I heard they were considering it. Also last I heard they were offered this stuff in first few days. But by Areva and KHG rather than by Sarkozy and Merkel.
Does US have robotics equivalent to KHG?

 

[hbjon]

on topic of chemistry... in what form would the Cs exist? Wouldn't it take away O from UO2 becoming Cs2O ? Then in water, CsOH ?
Cs is far more reactive than U. I'd expect any Cs to immediately grab the oxygen from UO2

Since there is speculation here, let me say that I think Ba takes the O2 and quickly disintegrates and that is where the Cs gets a hold of it.

 

[M. Bachmeier]

I sincerely apologize to the members for inadvertently including two videos of the #1 explosion.

Interestingly enough, one has sound and the other doesn't. Gee, I wonder how that could have possibly happened just like with the #3 videos...?

That said, my error does nothing to help you prove that the video of the #3 explosion with sound is legitimate. MiceAndMen asked good questions.

I don't think anybodies trying to prove anything. In fact when I looked at the audio track my first objective was to try and determine if it was a fake (re: null hypothesis).

Having no strong reason to disbelieve, I tried to fit it together nicely. It did... So, I'm strongly inclined to believe the sound track I've presented to be legitimate.

 

[TCups]

I sincerely apologize to the members for inadvertently including two videos of the #1 explosion.

Interestingly enough, one has sound and the other doesn't. Gee, I wonder how that could have possibly happened just like with the #3 videos...?

That said, my error does nothing to help you prove that the video of the #3 explosion with sound is legitimate. MiceAndMen asked good questions.

StrangeBeauty:

No apologies needed and no worries, sir. That Steinbeckian skeptic does indeed ask some penetrating questions doesn't he?

It wasn't my intent to prove authenticity of the soundtrack or disprove it, and if I err, it is perhaps on the gullible side, as I usually presume something is authentic until it has been proven not to be. But if I erred on this one, it certainly wasn't because I hadn't considered the possibility or made some rudimentary effort to confirm it was authentic.

 

[ian_scotland]

RE Unit 4 roof slice theory...

I've been following this thread closely since 2nd week or so, but have mainly kept my mouth shut as I struggle to comprehend the "science bits". However, as an architect I grasp the "construction bits" reasonably well (thankfully!)

I have however been bowled over by the minds (an due thought processes) of several forum members here. Thank you for providing an insight into the Fukushima situation for me.

I have serious doubts that anything fell onto the roof of unit 4 or sliced through it. The north side of unit 4 is seriously out of shape. It is bulging out around the service deck level significantly. Together with dislocated columns and beams to the top-most NE corner, may I suggest that what we see in the photos is a structure that came within a hair's-breadth of looking like it's neighbour, unit 3. I shall attempt to find a photo and overlay a straight line tomorrow if I have time.)

As the main north wall ballooned outwards, its (possibly un-restrained) top has caved inwards, buckling the steel roof cross-bracing in the NW corner. Whether this significant blast removed the cross-bracing from the rest of that roof bay or it simply collapsed under the roof covering I haven't looked at in detail yet.

(Having now been able to look over the Oyster Creek constructional drawings -many thanks for the links - it is clear that large conduit voids, general services penetrations,varying wall masses etc would have a great effect on how the energy from any explosion would be channeled throughout any given level of the building.)

Commercial roof structures/coverings such as initially apparent in these reactor buildings tend to be corrugated uluminium (aluminum for USA folks) or steel sheets. These are what we can see scattered all around. They are fixed together with just enough bolts/nails to prevent uplift from the negative pressure above the building from gales. On top of these (as TCups has correctly researched) is typically a lightweight foam topped with approx 2-10mm of built-up waterproofing layers (usually rubber, bitumen or plastic based).

I've seen quite a few cases of building/roof failure, and would suggest that such a roof as discussed here would have neither the mass nor the rigidity to slice through/impact/bend the heavily reinforced concrete wall frame of unit 4.

Also to be discounted is any other flying debris (from unit 3). I'm pretty certain that one of the main posters on this forum has already posted an image of unit 3 post-BOOM, with unit 4 apparently intact. I shall try to dig it out and attach here too.

Sorry I've not gone into more depth just here - its not far from midnight and I've had a chaotic day of chasing my wee boy around, nappy (diaper) changing and general mayhem.

ps. The other good thing about following all the posts on this thread is that I've saved a fortune by not frequenting a certain on-line auction site over the past weeks, and am now in my wife's good books

 

[dh87]

In a previous post (#4111) I calculated the concentration of a 5% gap release of Iodine-131 into the pool from just the last core offloaded. Unfortunately I only accounted for a 30 day decay. Mr. Gunderson correctly indicated that the unit was shutdown 4 months before the accident. It has been a month since. So I repeated my calculation accounting for 180 days (6 months) of decay.

From an ORIGEN2 calculation of a BWR the core inventory of I-131 at 6months after shutdown is 5.03E-3 Ci per MW. Assuming 760 MW Electric and a 33% efficiency for Unit 4 leaves a total I-131 at the time of the accident of 5.23E5 Ci. In Taking 5% (gap release) and converting to Bq leaves 9.67E14 Bq.

I assumed a Fuel Pool of 40' by 20' by 40' deep. That converts to 1.81E9 cm^3.

Possible concentratiion of I-131 after 6 months in the fuel pool with only 5% of the source term released is up to 5.34E5 Bq/cm^3.

Personally I think Mr. Gunderson is absolutely correct when he ridicules TEPCO's explanation of Iodine deposition. But you do not need criticality to explain the concentration of I-131 they reported.

I try to keep reminding people that just because an isotope has a short half life does not mean it disappears in a few half lives. Half of a big number is still a big number. I-131 will likely be detectable beyond a year after shutdown.

In my first post, I'll try not to say anything too foolish, although I will be answering a post from 6 pages ago. I don't see that TEPCO's explanation is necessarily wrong. The volatilized iodine or iodide salts will stick to dust or other small particles. These may land on surfaces from which they can be blown elsewhere. When they land in water, the ions are permanently trapped. All the ions and the iodide dissolve in the water. Hence, Gunderson's calculation of how much I/I- had to be released to get 200 Bq/ml in SFP#4 isn't right. The SFP will concentrate the iodine from everywhere. Also, TEPCO added seawater from around the plant to cool the SFP. This seawater had radioactive iodine in it, and it's been concentrated by evaporation.

Some posters were wondering about the temperature of SFP#4. TEPCO reported 90 °C (http://www3.nhk.or.jp/daily/english/13_35.html ) when they measured the radioisotopes.

Two chemistry points. 1. The boiling point of I2 is 184 °C. It's hard to boil it out of water. 2. Iodine (I2) is pretty soluble in the water, and its solubility is increased by iodide in the water. In this case, there's probably enough iodide in the seawater.

 

[Borek]

1. The boiling point of I2 is 184 °C. It's hard to boil it out of water.

Boiling is not that important - iodine easily sublimes, so it doesn't have to go through liquid phase to become airborne.

 

[TCups]

HAPPY EYES WILL FOOL YOU EVERY TIME.

Well, once again, I fear my eyes are happy when they see what I expect them to see. But if I go brain dead and start from scratch, it is a lot easier to discover the obvious!

Take another look at the "undamaged" shot of Bldg 4 after the Bldg 3 explosion. . .

https://www.physicsforums.com/attachment.php?attachmentid=34633&d=1303253626

Now take a look at the attached hi-res photo "after" Bldg 4 has been damaged . . .

Does anyone else see what I now see??!

No hints. You have to find it yourself.

 

[Astronuc]

Boiling is not that important - iodine easily sublimes, so it doesn't have to go through liquid phase to become airborne.

and as far as I know, most iodine compounds are unstable, i.e., they tend to readily decompose in favor of other compounds + I₂.

 

[NUCENG]

Well, you could zip and upload them to a sharehoster... ^^

This would be very nice. :)

https://rapidshare.com/files/458267452/Upload_Refs.zip

let me know if I did this right.

 

[Dmytry]

and as far as I know, most iodine compounds are unstable, i.e., they tend to readily decompose in favor of other compounds + I₂.

hmm mmm. Iodine is a strong oxidizer and tends to readily react with a lot of compounds, oxidizing them or even replacing something.

 

[ian_scotland]

HAPPY EYES WILL FOOL YOU EVERY TIME.


No hints. You have to find it yourself.

Come on, just a small hint, the suspense is killing me here. Its way past my bed time and I can't wait another 6 hours!

 

[razzz]

HAPPY EYES WILL FOOL YOU EVERY TIME.

Well, once again, I fear my eyes are happy when they see what I expect them to see. But if I go brain dead and start from scratch, it is a lot easier to discover the obvious!

Take another look at the "undamaged" shot of Bldg 4 after the Bldg 3 explosion. . .

https://www.physicsforums.com/attachment.php?attachmentid=34633&d=1303253626

Now take a look at the attached hi-res photo "after" Bldg 4 has been damaged . . .

Does anyone else see what I now see??!

No hints. You have to find it yourself.

That was a bad link for me.

Guessing as always, but as been noted before Unit 4 appears to have exploded from the lower portions of the building causing the bottom to flare out and push the top inward and apparently no flight time for that roof section that remains fairly intact (per our newest architect poster) more like pushed and slid inward.
As you look at the picture, ground level or lower, a couple of venting areas bottom of pic and on the right side of building esp. underneath the piping that travels away passing between the next two buildings where there appears to be blast damage again coming from Unit 4 near or at ground level, one building taking the brunt of blast.

Also, sound tracks can be uploaded to YouTube if you just put in a dummy video (still shots, graphics, etc.)