Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[AtomicWombat]

It seems to me that it is fundamentally important in situations like this for the public to have complete confidence that the government is acting in its interests.

This is concerning:
http://www3.nhk.or.jp/daily/english/04_10.html"

 

[mantrogo]

Since the Gundersen thing has come up again, if I may I'll just repeat an earlier post. Looking at the I131 Cs137 ratios that have been confirmed there is no evidence of recent criticality. Given the production yields for I131 and Cs137 from fission reactions (ratio of about 1:2) and given their respective half lives you can model the ratio of one to another as a fuel rod ages and convert that to activity ratio (ie Becquerels). What TEPCO is reporting is consistent with spent fuel.

In the same post I also included a reference to an IEEJ paper looking at what happened in Kashiwazaki-Karima after the 2007 Niigata earthquake. I know it's a different design but they saw leakage of water from spent fuel pond (basically waves splashing up onto the floor) that then escaped out of cable ducting. How much do you want to bet that TEPCO hadn't got around to fixing that particular problem elsewhere in the nuclear fleet?

 

[AntonL]

Have we ever discussed any additional containment on the top floor of Unit 4
IR image of 23 March - what could this containment be - fuel casks?
or is this simply residue warmth from the reactor containment ,
huge amount of concrete will store lots of heat
but then I expect it to be circular, hex but not rectangular - anythoughts

 

[orndorf]

What TEPCO is reporting is consistent with spent fuel.

What TEPCO is reporting...there should be an independent company monitoring the levels.

Talk about a conflict of interest,its like presiding over your own trial.

 

[TCups]

Have we ever discussed any additional containment on the top floor of Unit 4
IR image of 23 March - what could this containment be - fuel casks?
or is this simply residue warmth from the reactor containment ,
huge amount of concrete will store lots of heat
but then I expect it to be circular, hex but not rectangular - anythoughts

There was an earlier picture that showed (and I am speaking from memory here) that the open containment at the level of the access floor on one of the reactors was square, and that the opening through the removed drywell cap was round.

If Reactor 4 were shut down and if water that is being added to replenish SFP4 traverses the open transfer chute, then the top layer of water over the containment might be relatively warm.

The arrow pointing to "containment" appears to be the opening to the primary containment and appears to be a square or rectangular area, not a round opening. But then, IR pictures are never high spatial resolution. The bar-like defect over the larger SFP4 is, IMO, the FHM and overhead crane. What is absent is any activity in a smaller pool west of the larger SFP, though it is possible it might be obscured by the overhead crane.

No answer has been posted to my earlier questions about the process of putting spent fuel rods in casks for transport. With two trucks out back for that purpose, one sans cask, and Unit 4 in shutdown mode, it would seem possible if not likely that cask transfer was in progress, though at what stage, we don't know.

 

[|Fred]

Why the lack of? Given the low IR temps recorded wouldn't it make sense for the round plug to be in place but slightly warm from the very hot (melting?) fuel rods inside?

The slab is about 2 meters thick (If I recall it was stated on page around #40) and made of reinforced concrete, I don't think concrete is a good heat conductor (may be mistaken) considering the crane (metalic) on top is enough to shield the thermal image . The only logical conclusion I could make is that the heat emitter is water )

Having said that it is far from a perfect fit..
First of where is the concrete slab ? Second how come is the crane on top of the reactor if the slab blew ? Third the utility pool is destroyed If it was water that we are seeing for heat emitter . I assumed SFP and slab communication door broken . One could assume the same on the utility pool...

Something does not fit right..



edit: futher more http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/2011-04-04-060000/plot-un3-full.png does not tell the same story at 0,4 plus Mpa the drywell sould not have leaked all that much

 

[|Fred]

The arrow pointing to "containment" appears to be the opening to the primary containment and appears to be a square or rectangular area, not a round opening. But then, IR pictures are never high spatial resolution.

Yes it is a rectangular area , it looks square because there is part of the roof shielding the heat
(grr.. I wish I was home..using a laptop with those image is ... grr) Anyhow, this rectangular area is the utility pool.

Is there a procedure in NPP refueling or inspection that lead to put rods in the utility pool ?

 

[TCups]

Yes it is a rectangular area , it looks square because there is part of the roof shielding the heat
(grr.. I wish I was home..using a laptop with those image is ... grr) Anyhow, this rectangular area is the utility pool.

Is there a procedure in NPP refueling or inspection that lead to put rods in the utility pool ?

Here's the higher resolution view of Bldg 4 again, without the arrowheads obscuring what is supposed to be illustrated.

http://i306.photobucket.com/albums/nn270/tcups/Picture41.png

I take the left hand "bar" defect to be the FHM, the "H bar" defect to be the overhead crane and both to be over the SFP4. That means the rectangular opening is the opening to the reactor access with the top removed and the equipment pool is cold. I believe that the transfer chute between the SFP and reactor containment opening is visible.

Remember, also, that steam and even warm water vapor could leave a signature. I think either steam or hot water vapor is escaping along the south edge of SFP 4 from under the FHM.

We have seen steam venting from the region of the reactor containment of unit 3 for some days. A loose plug with steam escaping might also leave a circular heat signal. In any case, it is deep doo doo, because the reactor containment of unit 3 is almost certainly breeched -- we are just debating the fine points, I believe, eg. "What caliber bullet was used to shoot President Lincoln in the head?", right?

 

[AntonL]

No answer has been posted to my earlier questions about the process of putting spent fuel rods in casks for transport. With two trucks out back for that purpose, one sans cask, and Unit 4 in shutdown mode, it would seem possible if not likely that cask transfer was in progress, though at what stage, we don't know.

Cask transfer was taking place at Unit 4 , even though the vehicles were parked outside unit 3

Look at the high res pics of unit 4 loading tunnel and you see a truck peeking its head out,
so in my opinion we can confirm fuel transfer (in or out) at Unit 4 was in progress

 

[TCups]

MECHANISM FOR CASK TRANSFER OF NEW AND SPENT FUEL RODS?

Cask transfer was taking place at Unit 4 , even though the vehicles were parked outside unit 3

Look at the high res pics of unit 4 loading tunnel and you see a truck peeking its head out,
so in my opinion we can confirm fuel transfer (in or out) at Unit 4 was in progress

Maybe at both 3 and 4? Or maybe new fuel was going in and old fuel was going out? It would be interesting to know the exact procedure for both transfer of new fuel rods into the building, and spent fuel rods out of the building. It would seem logical to me that there might be a small accessory pool for cask transfer, as I have suggested earlier. At some point, the overhead crane has to hand off the dry cask to the wet operations of the FHM, and I doubt that means plopping a dry cask with new fuel rods into the SFP.

It would make more sense to put the dry cask in a small pool, pumped dry, then flood the small pool, then open the cask underwater, then transfer the new rods directly to the reactor core underwater. It would also seem logical to transfer the spent rods under water to a flooded small pool, containing an open cask, then to close and decontaminate the exterior of the cask before the crane takes it back for loading on the truck. Just guessing.

They would probably take every precaution to keep the overhead crane from being contaminated, whereas the FHM, or at least its mast, is designed to live with the high levels of radioactivity in the lower depths of the SFP and reactor core. I bet the mast rarely if ever comes completely out of the water.

It is pretty darned sure that the new fuel rods get nowhere near the spent fuel rods in the deep part of the SFP. The only time that proximity would occur is in the core of the reactor.

It sure would answer a lot of important questions if accurate drawings of the floor plans of the Fukushima Units 1-4 were available.

Addendum:
http://www.chicagotribune.com/news/nationworld/sns-graphic-transfer-cask-gx,0,4629408.graphic

http://www.simutechgroup.com/images/Brochures/Industry/Nuclear/EX219.pdf

Here are drawing of the casks and temperature profiles of the inside of the casks.

 

[artax]

no plans found of floor layout, but I have been searching. there'ssome useful annotaded photographs here:-

http://allthingsnuclear.org/post/4261422055/annotated-photos-of-fukushima

http://cryptome.org/eyeball/daiichi-npp2/daiichi-photos2.htm

Good image this one:-

http://cryptome.org/eyeball/daiichi-npp2/pict59.jpg

 

[bytepirate]

Since the Gundersen thing has come up again, if I may I'll just repeat an earlier post. Looking at the I131 Cs137 ratios that have been confirmed there is no evidence of recent criticality. Given the production yields for I131 and Cs137 from fission reactions (ratio of about 1:2) and given their respective half lives you can model the ratio of one to another as a fuel rod ages and convert that to activity ratio (ie Becquerels). What TEPCO is reporting is consistent with spent fuel.

please check my calculations, derived from http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110331e18.pdf":

activity:
3.25 * 10^12 Bq/g caesium-137
4.8 * 10^15 Bq/g iodine-131

values (unit 1):
5.9*10^0 Bq/cm^3 caesium-137
4.3*10^2 Bq/cm^3 iodine-131

leads to:
1.8 * 10^-12 g/cm^3 caesium-137
0.9 * 10^-13 g/cm^3 iodine-137

thus a I/Cs ratio of 1:20 which is pretty much, what i would expect from the core almost 3 weeks after shutdown.

the ratio for unit 3 of 1:650 looks more like spent fuel to me.

(assuming, that both elements are represented in the subdrain in the same ratio as they are in the rods)

i might be *completely* wrong, but as nobody has answered to a previous post of mine, i tried the calculation on my own ;-)

 

[artax]

the reasuring thing is this water is only 100 times the ALLOWED limit. I assume the limit they talk about is for continued release, and this will hopefully just be a (relatively) small volume compared to Nuclear power routine effluent.
However when they quote these allowed limits, I wish they would specify exactly what is stated in the document, whether it's a limit for brief releases, or continued emissions. And whether allowed releases and concentrations are isotope/half life dependent, or just activity dependent.

 

[tsutsuji]

http://www.yomiuri.co.jp/national/news/20110404-OYT1T00580.htm has a diagram showing how they plan to connect the various water tanks to eventually dispose of the water.

 

[mantrogo]

Hi bytepirate - here's the way I did it.

given atomic mass + half life you can deduce the ratio of the number of particles of I 131 and Cs 137 that give rise to the TEPCO readings of 25th March (the ones I used where they said that while Technetium etc might be wrong, I and Cs were right).

Comes out to approx 12,000 (Cs) to 1 (I). The production yield is 2.5 (Cs) to 1 (I) [NB only source is Wikipedia - anyone got anything definite?].

There are two further things to bear in mind: 1) the reading was taken 14 days from accident - since we know the half lives you can allow for that and work out what the relative particle numbers would have been at the time of accident and (2) more importantly, consider what the fuel would have looked like when burnt.

Since Cs 137 has a half life >>> I 131 and >> the life span of a fuel rod then as fuel gets burnt the Cs particles build up while the I 131 will peak and then decline in number. This relationship depends on the number of uranium decays that occur over the life of the rod as (i) the number of uranium atoms declines with burn up and (ii) neutron poisoning occurs. I assumed that there was a simple linear relationship for the number of reactions with age of rod and it declines to zero at end of rod life. This may be unrealistic - but it will do and looking at graphs of Pu enrichment with burnup, it's not a million miles off!

Do the maths and you see ratios of 12,000:1 in and around the last days of a rod. According to the IAEA the reactor has been running more or less continuously over the last few years - hence there is every reason to suppose that the rods in a live core have an average life at about half the life span of a rod.

I don't know what that life span is, but whether it be 4, 5 or 6 years (different numbers from different web sites), the average rod ratio Cs:I would be somewhere in the low hundreds. No way to get to 12,000:1 after 14 days.

 

[Joe Neubarth]

the reasuring thing is this water is only 100 times the ALLOWED limit. I assume the limit they talk about is for continued release, and this will hopefully just be a (relatively) small volume compared to Nuclear power routine effluent.
However when they quote these allowed limits, I wish they would specify exactly what is stated in the document, whether it's a limit for brief releases, or continued emissions. And whether allowed releases and concentrations are isotope/half life dependent, or just activity dependent.

Years ago, the ALLOWED LIMIT was for normal operations. The limits were very restrictive. If any detected release exceeded the allowed limits, the Power Plant had to report itself to the Regulatory Agency along with recommendations to correct the problem that caused the high reading. Seeing how TEPCO was taking sea water samples where the readings would be low, (Incoming currents as opposed to outgoing currents from the shore near the effluent release) I can only guess that they had very little reporting to do in the past.

I do not know if the requirements have changed in the recent past.

 

[NUCENG]

please check my calculations, derived from http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110331e18.pdf":

activity:
3.25 * 10^12 Bq/g caesium-137
4.8 * 10^15 Bq/g iodine-131

values (unit 1):
5.9*10^0 Bq/cm^3 caesium-137
4.3*10^2 Bq/cm^3 iodine-131

leads to:
1.8 * 10^-12 g/cm^3 caesium-137
0.9 * 10^-13 g/cm^3 iodine-137

thus a I/Cs ratio of 1:20 which is pretty much, what i would expect from the core almost 3 weeks after shutdown.

the ratio for unit 3 of 1:650 looks more like spent fuel to me.

(assuming, that both elements are represented in the subdrain in the same ratio as they are in the rods)

i might be *completely* wrong, but as nobody has answered to a previous post of mine, i tried the calculation on my own ;-)

I was working on an answer to your first question. Here is what I found.

The equilibrium core at time of shutdown in a BWR analysis based on the ORIGEN-2 code predicts an initial I/Cs ratio of about 8. At 30 days it is down to 0.6. So the theory is that this could be used to evaluate a time of last fission. However, this is complicated by the fact that Cs and iodine are different chemically as well at half lives. Some iodine is released as gaseous Iodine. Others chemically combine to form particulates. The most common particulate is actually cesium iodide CsI. Transport of gaseous, and particulates are different.

If you look at the ratios of samples in the seawater, airborne gas samples, airborne particulates, and in the leakinbg trench, I fount I/Cs ratios ranging from 120 down to 0.2. Clearly release paths and sample locationns make a difference. In other words the only legitimate use of this method may require an assumption that release paths remain unchanged over time and that a trend for a specific sample point may then produce useable data.

 

[artax]

Years ago, the ALLOWED LIMIT was for normal operations. The limits were very restrictive. If any detected release exceeded the allowed limits, the Power Plant had to report itself to the Regulatory Agency along with recommendations to correct the problem that caused the high reading. Seeing how TEPCO was taking sea water samples where the readings would be low, (Incoming currents as opposed to outgoing currents from the shore near the effluent release) I can only guess that they had very little reporting to do in the past.

I do not know if the requirements have changed in the recent past.

Thanks,

"the power plant had to report itself"

that just cracks me up that does!

 

[mantrogo]

"ALLOWED LIMITS" - may be like the allowed limits for food and driking water - remember that scare a few days ago? The allowed limits (in bq) are set by reference to a level where incidence of cancer would not increase assuming consumption over _an_entire_year_.

 

[Giordano]

Very useful plots but data don't seem updated since Apr 02. And I think latest release from NISA is 70 (at least in English).

----

Pressure in RPV 1 is increasing. Here is the latest update from JAIF (61) : http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301899872P.pdf

Is that a big concern? Is there a greater risk of H2 explosion if the pressure increases? Or do they have to release pressure?

We have been informed about that they we were planning to inject N2 in unit 1 to reduce risk for explosion. Does anyone know if this has been successful?

No comment on this!?

Still rising:
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301918121P.pdf (update 62)

 

[hbjon]

It seems to me that it is fundamentally important in situations like this for the public to have complete confidence that the government is acting in its interests.

This is concerning:
http://www3.nhk.or.jp/daily/english/04_10.html"

One can't help but wonder if dead peasent insurance has not been taken out on these poor souls. In some countries they would assemble a panel to investigate into this. Make sure no one benefits by a tragedy. That would be very disturbing. Fearlessly go wherever your research takes you gentlemen. If it is true for you, it is true.

 

[Giordano]

the reasuring thing is this water is only 100 times the ALLOWED limit. I assume the limit they talk about is for continued release, and this will hopefully just be a (relatively) small volume compared to Nuclear power routine effluent.
However when they quote these allowed limits, I wish they would specify exactly what is stated in the document, whether it's a limit for brief releases, or continued emissions. And whether allowed releases and concentrations are isotope/half life dependent, or just activity dependent.

When Kyodo has been stating something times "the limit" before, it has turned out to be the limits mentioned in this document (which specifies a limit per nuclide):

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110331e13.pdf

----

Tepco hasn't reported this type of nuclide analysis of sea water since Mar 30. They used to report once per day before.

 

[artax]

Isotope detection explained,

http://www.washingtonpost.com/natio...t-it-for-clues/2011/03/30/AFfnQBHC_story.html

And just to cheer you up!

 

[wallu]

The strong evidence says reactor 3's primary containment was breeched at the time of the blast (as was Unit 2's). Fred and I agree on that I am pretty certain. I can understand a blast from the primary containment loosening the plug -- maybe even leaving it completely askew, or fragmenting its sections, if it is in multiple sections. But I still believe it was the FHM that went ballistic, and that most of the blast diverted through the transfer chute. I am not sure it makes a lot of difference either way at this point. The biggest problem is and will continue to be the hottest thing in the thermal images of B3 and B4 -- the spent fuel pools, which were never "contained" from the beginning, and this has been my greatest worry from the onset of the first explosion. What a mess . . .

Hello!
My first post after reading this thread for last couple of weeks. I couldn't not to register after I looked at this photo.
http://www.reuters.com/news/pictures/slideshow?articleId=USRTR2KAAL#a=25"

Doesn't it look like whole top floor of reactor level is gone? Compare to this pic for reference where top floor should be.
http://www.reuters.com/news/pictures/slideshow?articleId=USRTR2KAAL#a=27"

In the first picture I don't see DW cap at all where it should be. Only big hole with steam coming out of it.

Also workers had some time after loosing all electrical power except batteries before things got dangerous. Couldn't they moved that big crane on top of reactor plug as precoution? If I'm looking correctly, east end of crane is still on floor it should be but west end has dropped one floor lower, becouse whole floor is gone.

I hope I'm helping...

 

[elektrownik]

And WFT is that ? How temp of empty core can be bigger than SFP with fuel ?
(This is reactor 4)
[PLAIN]http://img854.imageshack.us/img854/1787/38415578.jpg

 

[|Fred]

[PLAIN]http://i.min.us/imQ6vm.jpg

 

[wallu]

[PLAIN]http://i.min.us/imQ6vm.jpg[/QUOTE]

I think your perspective is a bit off. If you move location of SFP more east where it's steam comes, then the red circle also moves east, right over the second steam source.

 

[TCups]

As before, but I may be wrong.

http://i306.photobucket.com/albums/nn270/tcups/aerial-floorplan.gif

I believe the photo is an AP Photo from the unmanned drone flyover, but I am uncertain of the original credit. Her is the unaltered original, as first posted here:

 

[|Fred]

the original picture is shot with a weird angle...
I made it more clear here.

the steam come from the utilitypool or the fringe between the utility pool and the slab hole
http://i.min.us/imMhCM.jpg

 

[|Fred]

reminder
https://www.physicsforums.com/attachment.php?attachmentid=33951&d=1301823916
https://www.physicsforums.com/attachment.php?attachmentid=33950&d=1301823916