Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[fluutekies]

The recent data from the analysis of water from SFP4 would seem to me to be strong evidence of leaking. Taking account of the decay of iodine-131, the data for all three measured isotopes indicates that the pool has lost half of the content of soluble matter it had 14 days ago.
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110429e13.pdf

Agree. Here my try for quantification of the leak of SFP4 based on Cs-isotopes:
L 12.2 m
W 9.9 m
D 11.8 m
V 1425.2 m3
m fuel 264.0 kg U
V net 1200 m3

Cs-137
93 Bq Cs-137/cm3 on 2011-04-28
55 Bq Cs-137/cm3 on 2011-04-13

Cs+ ion is non-volatile & can only leave by leaks or decay, decay is negligible (15 days/30 years).

59% Cs-137 remains in SFP after 15 days. Assuming homogeneous distribution by convection and diffusion.

710 m3 remaining volume with original 93 Bq Cs+
490 m3 lost volume with 93 Bq Cs+
15 days
23 L/min
1.4 m3/h
32.7 m3/day ~ -30cm level/day

This simple model assumes that the total volume is lost once, refilled & homogenized again.
In reality the loss will be continuous & refilled periodically.
The calculated loss by leaking of about 23 L/min therefore is the lower limit. Under the real conditions (periodic refill & continuous homogenization), therefore the leak is probably a factor of 3 -5 higher (my guess). But this quantity (75 - 150 L/min) is still small enough to get undetected somewhere in or outside the building.

4.4E+11 Bq Cs-137 leaked in this period from SFP4. Not a small amount. At least as it is expressed in Bq/L instead of /cm3 and multplied with the volume for the absolute inventory.
Same calculation with Cs-134 gives comparable result.
Edit: Read some remarks after posting: both volumes are assumed equal which seems reasonable due to the fact that TEPCO is refilling daily.

 

[razzz]

I thought I read TEPCO was doing a balancing act for SFP #4, trying to keep the weigh factor down with less water and their figures of re-watering were inline with boil off losses. So they allow the pond to get so hot but not to hot and still keep coverage over the fuel assemblies. In the meantime, they try to figure out if there is a leak or not. First there is then there isn't.

 

[MadderDoc]

The measurements on the diagram are not consistent. When scaled appropriately along the Y axis (I used Autocad), the distances between the X coordinates are way off. And vice versa. I would trust the XY numerical values given, but simply tracing the outlines of things will not yield accurate shapes or positions.

Allright. I took a wrestle with that map, and I do see what you mean, it's not that easy using this map which surely could be better. Now, one should not let 'better' be the worst enemy of 'good enough' , and how much precision do I actually need. I quickly found out that a pair of extra assumptions, the reasonability of which you may not be aware, would make things a lot easier.

a) it is a fair assumption that the basefloors of the reactors are quadratic.
b) it is a fair assumption that units 2-4 have closely the same dimensions.

Using those assumptions, and a ruler measurement of a marked up 125.000 m distance in the NS direction of the map, I get estimates that the basefloors of Unit 2-4 are 46.4 x 46.4 meter (topfloors 46.3 x 33.4 m). Unit 1 is smaller, the estimate for that using the map gave me 40.6 x 40.6 m, impressively close to the data we have in diagrams of sections of the generic sort of reactor, which unit 1 is one of,

I am sure some luck was involved there but I took it, that the method was kinda working. I should add that there is no markup of the topfloor in unit 1 in the map, so the only recourse for that is the generic section diagram, the estimate for the topfloors of unit 1 becomes 40.6 x 30.4 m.

 

[bytepirate]

therefore the leak is probably a factor of 3 -5 higher (my guess).

no need to guess ;-) the factor is ~1.5 (http://en.wikipedia.org/wiki/Compound_interest: e^0.41)

 

[Jorge Stolfi]

[Could you confirm] the depth of the floor basement in the reactor building, below the line of the platflorm ground? (probably n°1 is different because it is a different reactor, but 2 to 4 should be similar). It should be something like 11 meters i think but maybe you can confirm this. The depth of the basement of T/B seems aligned with the one of the R/B so this info could help me to check and scale the sketch i captured on the NHK.

These are the only blueprints that I have which seem to match the photographs of exploded buildings:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un3_cut_N_1.png (E-W cut)
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un3_cut_W_1.png (N-S cut)
http://www.ic.unicamp.br/~stolfi/EX...a/povray/blueprint/good/un3_service_floor.png (service floor plan)

The first one (E-W cut, looking towards north) seems to be a hurried sketch by someone who had at least some technical drafting experience.

The second one (N-S cut) is rather amateurish: the circles seem to be drawn with templates rather than compass, the sides of the building are not parallel, the midline is not exactly in the middle, etc. More importantly, the spacing of floors in the drawing does not match the numbers on the side. Also the N-S size of the SFP does not match the photos.

The third one (service flor plan) is also rather amateurish, just a a sketch done with some common illustrator program (rather than Autocad or such). The original was visibly stretched N-S. I fixed the image to match the true(?) aspect ratio of the building, but then the reactor opening ended up slightly squashed the other way. Still, the positions and sizes of pillars and other details seem to match the photos quite well.

As you can see, the only numbers explicitly given in those drawings are the floor heights (in meters) above the local standard reference level ("O.P."). The external ground surface is at OP+10.000 meters, and the floor of storey 1 ("ground floor") is at OP+10.020 meters (i.e only 2 cm above the external ground). CORRECTION: OP+10.200 , i.e 20 cm above external ground. The basement floor is at OP-2.060 meters (not counting the trench where the torus sits), and the bottom of the concrete base is at OP-6.060 meters. The buried wing on the West side is an extension of the basement, and that on the East side is an extension of basement plus storeys 1 and 2. The terrace roof seems to be at the same level as floor 3 inside the building.

The following file contains the measurements of units 2-4 that I am using in my POV-Ray models. Note that many of the numbers are my estimates ("E") obtained by measuring distances on the drawings and doing the appropriate scaling. Many others are just guesses, still to be confirmed ("TBC").

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/un4_dimensions.inc

2) seen from the top, and also for scaling purposes, the exact outside dimensions of the R/B 1 to 4 (1 is a little bit smaller maybe)? .

If the N-S and E-W cut drawings can be trusted, the middle part of buildings 2--4 (storeys 1 and 2) seems to be approximately square, 47.5 meters on each side (give or take 1 meter, perhaps). The top part (storeys 3 to 5) is about 8 m narrower: 35.5 meters E-W by 47.5 N-S. The basement extension on the West side is about 10.0 meters wide.

Unit 1 is indeed smaller. For that one we have actual engineering blueprints (with the original caption "Fukushima Daiichi Unit 1" at the corner) with hundreds of accurate measurements. Unfortunately, only for the N-S and W-E cuts thrugh the reactor axis:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un1_cut_N_1.png (E-W cut)
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un1_cut_W_1.png (N-S cut)
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/misc/un1_blueprint_big.jpg (both, hi-res, big file)
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/un1_dimensions.inc (dimensions I am using)

All these blueprints were uncovered by other contributors to this thread, and the original documents are available through previous posts.

I hope it helps...

 

[MJRacer]

Ongoing criticalities at Unit 2?

http://www.glgroup.com/News/TEPCO-D...e-Leaking-Fukushima-Daiichi-Unit-2-53751.html

 

[Jorge Stolfi]

Hey Jorge Stolfi, you seem to know your building elevations so...if the RPV cap at the join to the vessel leaks and vents, what level or plane would it be projecting or slicing through in relation to Unit 3? Or if you cut the Unit 3 down to the elevation level with the RPV flange (like cap removed), what would it look like on your modeling?

Here is the current version of my model:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/out/fig_un4_building_cut_NW.png

If I understood the blueprints correctly, there is a washer-like steel plate connecting the drywell neck (yellow) to the reactor pressure vessel (gray). That plate separates the bulb-like drywell proper from the refueling pool --- the cavity on the service floor where the shroud is located. That partition is supposed to be water-tight; AFAIK, in normal operation and most core maintenance work the refueling pool is filled with water, while the drywell is, well, dry. So if the drywell is overpressured and the shroud joint gives way, the gases should blast sideways into the refueling pool.

However, the flanges connecting shroud and drywell seem to be rather massive things held together with a zillion heavy bolts. So I would expect that the walls of the drywell will rupture at some weld somewhere else, well before the bolts do. Is that correct?

 

[jlduh]

Ongoing criticalities at Unit 2?

http://www.glgroup.com/News/TEPCO-D...e-Leaking-Fukushima-Daiichi-Unit-2-53751.html

I repost the graphs for clarity:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110428e14.pdf

As i got no answer on my question i ask it again: don't you find these numbers globally high comparing them to the water samples of SFP 4?

 

[Jorge Stolfi]

Re Jorge's estimate of the SFP cavity dimensions, yielding a volume ~1690 m³

The NISA number is given as the water volume of the pool. It may be the equivalent of the SFP concrete cavity minus volume of steel liner minus volume of equipment installed inside the pool (e.g. heat exchangers).

Moreover, some sketches and phtographs seem to suggest that part of the raw SFP space is taken up by the cask loading(?) pool (not shown in my models). That would be a block of concrete about 3.8 m x 3.8 m, with a cylindrical well down the middle, flush against the NW corner of the SFP and spanning its whole depth. The well in this block seems to be about 3m in diameter, and is connected to the SFP by a narrow gate of unknown depth. If that thing really exists, presumably it serves to hold the "dry" casks under water while the fuel is loaded and unloaded. In that case, from the ~1690 m³ you should subtract ~95 m³ to get the free volume of the SFP.

Also note that the water level in the pool is normally at some distance below the service floor.

 

[default.user]

I repost the graphs for clarity:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110428e14.pdf

As i got no answer on my question i ask it again: don't you find these numbers globally high comparing them to the water samples of SFP 4?

Excuse my bad English.

We talk about criticality in Germany for 4 weeks.
German physicist from very unpleasant conditions in the reactors.
I can give you, unfortunately only German interviews, if you like.

There are no more news to Fukushima Daiichi.

 

[Jorge Stolfi]

Some of those handles (and the caps of the bundles themselves) seem melted, in particular those in the rack that is partly visible in the bottom right corner, while others are simply not visible above the tops of the racks. I believe they call that "total meltdown"?.

Beware that a lot of roof debris rained down on the SFP after the explosion. The top edges of the rack walls sem to be higher than the top of the assemblies. If so, it is expected that the debris have collected over the latter. Only the larger pieces remained atop the walls. So what seem like damaged assemblies may be just assemblies covered by debris.

By the way, those tech reports on convective cooling of fuel in the SFP seem to ignore the possibility that the water flow up through the assemblies could get blocked by a layer of concrete rubble...

 

[default.user]

http://de.wikipedia.org/wiki/Edmund_Lengfelder

He said four weeks ago:

There is no way to cool a meltdown.
He says that a meltdown is to stop only by its own momentum.

All work at the reactor are unnecessary.
Are only means to avoid the radiation exposure of people and staff.

Humanity before ecology.

 

[Jorge Stolfi]

The video taken on March 11th shortly after the tsunami shows a large portion of the staircase to be still on the building, except the uppermost part of the staircase which is missing. The video does not give a view to the lowermost part of the staircase close to the ground level to see whether is has sustained any damage, but it would be reasonable to expect at least some damage to it since this part of the staircase was inundated by tsunami water with floating debris.

My comments were based on the right half of this image from a previous post, allegedly a photo taken after the earthquake (and tsunami?) but before the #4 explosion:

[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/reactor4-S-7.png

In this photo the staircase seem to be still there, whereas the Mysterious Green Box has been replaced by the Mysterious Hole With Mickey Mouse Ears.

Note that the "Dark Goo Flowing Down From The Terrace" is already there.

If [by the Big Greenish Closet] you mean the apparent green box standing at the _foot_ of the wall, I think it is about the right size (I estimate the dimensions of the green box to be about 4 x 4 x 2 m).

The Mysterious Green Box should be at least 6--7 m tall to match the height of the Mickey Mouse Ears. On the other hand, judging by the ground-level photo below, the Big Green Closet may be quite a bit taller than that. (The terrace is 17 meters above ground level.)

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/reactor4-S-6.png

If the scenario of earthquake damage making the box come off is assumed, this is one of the places it could have ended up. It might initially have fallen down more or less vertically during the earthquake, taking with it the upper part of the staircase.

The photo above seems to indicate that the staircase was still there after the Mysterious Green Box disappeared.

The tsunami waters could then have made the box end up in this corner, behind other debris.

No need to invoke the tsunami. See:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/reactor4-S-5.png

The Big Green Closet either was attached to the wall all along (covering part of the window?) , or is hanging from the terrace by cables/pipes/whatever (the true nature of the "Dark Goo Flowing Down from the Terrace").

 

[default.user]

To put it together.

Both scientists believe that a particular [edit] nuclear fusion can not be controlled.

Both scientists have exquisite experience through Chernobyl.
Both scientists are not particularly popular in Germany.
Neither in East nor in West Germany.

So, how can you cool a core melt with water, without the danger of a steam explosion?

 

[Jorge Stolfi]

Someone posted this map of Fukushima I plant:

http://gyldengrisgaard.dk/fuku_docs/plant/

The overall layout may be correct, but the outlines of reactor buildings 3 and 4 are somewhat misleading. Apparently the drawing shows the outline of the ground floor of each reactor (which is indeed square). The conspicuous top part of the building has actually a rectangular floorplan. The 3rd floor terrace on the east side, between the top part of the reactor building and the turbine building, is about 12 meters wide.

 

[hbjon]

Ongoing criticalities at Unit 2?

http://www.glgroup.com/News/TEPCO-D...e-Leaking-Fukushima-Daiichi-Unit-2-53751.html

I think I can safely say that that would be very distubing if that was indeed the case. I don't know if it is impossible, but getting control rods inserted into a blob of molten corium that is distilling within the rpv seems quite unlikely. Splashing borated water on it isn't going to do anything immho.

 

[Jorge Stolfi]

I get estimates that the basefloors of Unit 2-4 are 46.4 x 46.4 meter (topfloors 46.3 x 33.4 m).

My estimates, from the blueprints and sketches shown in my pevious post, are 47.8 x 47.8 m for the ground floor, 35.8 x 47.8 for the service floors (at the external wall surfaces). Total height (from ground floor to upper side of roof, no counting the parapet) is given as 45.520 m.

Unit 1 is smaller, the estimate for that using the map gave me 40.6 x 40.6 m, impressively close to the data we have in diagrams of sections of the generic sort of reactor, which unit 1 is one of.

By adding numbers from the blueprint I got 41.560 x 41.560 for the ground floor, 31.420 x 41.560 for the service floor (at the external wall surfaces). For the total height (from ground floor to upper side of roof, not counting the parapet) I get 44.400 m.

 

[Jorge Stolfi]

CORRECTION: In a previous post I gave the ground floor height of reactor #3 (and presumably #4) as OP+10.020. Per the blueprints/sketches, it should be OP+10.200 , i.e 20 cm above external ground level (OP+10.000)

 

[MiceAndMen]

Ongoing criticalities at Unit 2?

http://www.glgroup.com/News/TEPCO-D...e-Leaking-Fukushima-Daiichi-Unit-2-53751.html

GL Group seems to be legit, but...

When Units 1-3 were all scrammed on March 11, 2011 from earthquake-caused station blackout

I thought the reactors scrammed when the first tremors of the earthquake were felt and the station blackout occurred later. The unnamed source also says control rods are "dropped in", but in a BWR they are pushed up from below by a hydraulic system.

Maybe he's right about what conclusions can be drawn from the data, but two sloppy mistakes in a very short analysis are like red flags for me.

 

[razzz]

Here is the current version of my model:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/out/fig_un4_building_cut_NW.png

If I understood the blueprints correctly, there is a washer-like steel plate connecting the drywell neck (yellow) to the reactor pressure vessel (gray). That plate separates the bulb-like drywell proper from the refueling pool --- the cavity on the service floor where the shroud is located. That partition is supposed to be water-tight; AFAIK, in normal operation and most core maintenance work the refueling pool is filled with water, while the drywell is, well, dry. So if the drywell is overpressured and the shroud joint gives way, the gases should blast sideways into the refueling pool.

However, the flanges connecting shroud and drywell seem to be rather massive things held together with a zillion heavy bolts. So I would expect that the walls of the drywell will rupture at some weld somewhere else, well before the bolts do. Is that correct?

I can't find the report and I am still looking for it but was reading where a GE Mark 1 RPV was tested by overheating and it vented/failed/leaked through at a specific area of the mating surfaces between the cap and vessel flanges. Yes, while bolt and nuts are typically stronger than welds (larger amounts of metal in play) the report I was reading concluded a predicted design flaw or weak area was proven during the test (guide pin areas?? Not sure). So anyway, I was thinking if a leak occur at the cap and flange, high pressure steam and accompanying heat is capable of 'slicing' through reinforced concrete just depends where it's directed. Also, if I read the diagram correctly, there is a gasket or 'O' ring between the two flanges that would be the first thing to fail with overheating.

 

[Dmytry]

How sure are you that there's working 'scram on first tremors'?
Anyways, it really doesn't tell anything we don't already know. The ratio of isotopes is wrong. Ditto for sfp #4 . We know that and we have enough expertise. Of course some can postulate unknown chemical mechanisms that would result in such ratio, and of course normally you test for criticality by checking for shorter lived isotopes, and so on and so forth. So it is still possible to plausibly deny criticality, so what, it's not a plausible denial contest here. The criticality is a big deal and has to be assumed until it is shown that there is no criticality.

edit: also, they could add some crap to cooling water, something that would transmute when absorbing neutrons. Then test for it's products of transmutation. That wouldn't even rely on the leaching of isotopes from the fuel, and with addition of amount of stable isotope of the element that test transmutes into, to be able to know the dilution rate, accurate analysis can be performed and the rate of fissioning calculated. (Of course they're never going to do this. This method I just made up. A lot of methods can be invented for testing for criticality)

 

[thewatcher]

My comments were based on the right half of this image from a previous post, allegedly a photo taken after the earthquake (and tsunami?) but before the #4 explosion:

[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/src/reactor4-S-7.png

In this photo the staircase seem to be still there, whereas the Mysterious Green Box has been replaced by the Mysterious Hole With Mickey Mouse Ears.

Note that the "Dark Goo Flowing Down From The Terrace" is already there.

Just wanted to say thanks for the knowledge and a great thread. Have just been reading for days. The only thing I want to add is a term for that Dark Goo Flowing that is beginning to appear around the net and seems appropriate. That dark goo is being called Poolium. Seems most appropriate.

Thanks again for all the analysis. Back to watching, learning and reading.

Credit goes to an 815 page thread on ATS here by JustMike
http://www.abovetopsecret.com/forum/thread672665/pg681

 

[Jorge Stolfi]

... the report I was reading concluded a predicted design flaw or weak area was proven during the test (guide pin areas?? Not sure). So anyway, I was thinking if a leak occur at the cap and flange, high pressure steam and accompanying heat is capable of 'slicing' through reinforced concrete just depends where it's directed. Also, if I read the diagram correctly, there is a gasket or 'O' ring between the two flanges that would be the first thing to fail with overheating.

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

 

[MiceAndMen]

Starting with Unit 1...

By adding numbers from the blueprint I got 41.560 x 41.560 for the ground floor, 31.420 x 41.560 for the service floor (at the external wall surfaces). For the total height (from ground floor to upper side of roof, not counting the parapet) I get 44.400 m.

Those are the same numbers for length and width I've been using as my yardstick (is there such a thing as a meterstick?). For the height I've been using 44.75 m. which looks to be the level of the main roof on those diagrams. The parapet, which I take to be 500 mm wide, probably adds between 200 and 500 mm to the absolute upper elevation.

As for Units 2-4...

My estimates, from the blueprints and sketches shown in my pevious post, are 47.8 x 47.8 m for the ground floor, 35.8 x 47.8 for the service floors (at the external wall surfaces). Total height (from ground floor to upper side of roof, no counting the parapet) is given as 45.520 m.

I calibrated a couple of the high-resolution images in Autocad using the above measurements for Unit 1. All of the photos available are from oblique angles, however, making it difficult to be precise about anything else. Perspective seems to be present in some pictures while others lack it. I attribute that to different cameras.

My best estimates for length and width of Units 2-4 is 47 m (a square) at the base with the narrow upper floors 35 m wide, but 35.8 x 47.8 is within my margin of error, which is considerable. Tomorrow I plan to see if the site map MadderDoc extracted from the TEPCO radiation reports can help refine my estimates.

 

[Most Curious]

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

I am far from an expert so will happily defer to one if they show up! Hopefully they will correct my errors.

The "washer" or refuel seal does have manholes. I assume they are open except when refueling requires the reactor well to be flooded. I would assume that considerable stress occurs as the reactor "grows" when heated to operating temperature.

The "maintenance door" is also known as an equipment hatch to move stuff into the DW. Obviously needed to service relief valves, recirculation pumps and pump isolation valves, among other things. The picture of Brown's Ferry under construction shows the hatch quite clearly. I understand the DW is a miserable and very crowded work space.

The vent pipes between the SC & DW are always open but do include a vacuum breaker. There is a bellows in the drain or vent lines between the DW & SC. (In my non-expert opinion a bellows may be damaged and leaking on unit 2 as it has the lowest failure pressure of the DW & SC components.)

 

[MiceAndMen]

The "maintenance door" is also known as an equipment hatch to move stuff into the DW. Obviously needed to service relief valves, recirculation pumps and pump isolation valves, among other things. The picture of Brown's Ferry under construction shows the hatch quite clearly. I understand the DW is a miserable and very crowded work space.

The vent pipes between the SC & DW are always open but do include a vacuum breaker. There is a bellows in the drain or vent lines between the DW & SC. (In my non-expert opinion a bellows may be damaged and leaking on unit 2 as it has the lowest failure pressure of the DW & SC components.)

This Mark I photograph is one of my favorites. It's the Browns Ferry 1 unit under construction in 1966. Both drywell and wetwell (torus) are clearly shown.

http://upload.wikimedia.org/wikipedia/commons/3/36/Browns_Ferry_Unit_1_under_construction.jpg

You can get a good sense of scale by looking at the man walking around the upper rim. Front and center there is what looks like an access hatch/airlock that would permit entry after the whole thing is encased in concrete. Further to the right there is a larger diameter hole; not sure whether this would be permanently sealed after construction. No bellows visible on the torus connecting pipes, but I'm sure they are there somewhere.

For what it's worth, anyone of the many drywell penetrations could provide a path for hydrogen to escape into the interior of the containment building if seals/valves/welds break in the wrong time and place.

Construction details differ between Browns Ferry 1 and Fukushima Daiichi. All are GE BWR4 reactors, but Browns Ferry 1 was designed to generate almost 50% more power than Fukushima Daiichi units 2-5. Maybe an expert could say if that means a 50% larger primary containment. I'm no expert but my guess would be 'yes' if only because the torus would need to be larger to accommodate more steam after the larger RPV ruptured. Physical dimensions might not scale linearly with power output, however.

http://www-pub.iaea.org/MTCD/publications/PDF/CNPP2010_CD/pages/AnnexII/tables/table2.htm

 

[razzz]

Perhaps. Also, I woud think that the upper regions of the drywell (around the flanges, under the "washer", and the "washer" itself), being more complicated than the drywell itself, are morelikely to have exceptional stresses and/or weaknesses. For instance, Unit 1 blueprints show manholes in the washer.

The blueprints also show that there is a maintenance door on the drywellnear its equator, located within a room on the ground floor with extra-thick concrete walls.

By the way, a question about the drain pipes between the torus and the drywell: are they permanently open, or can they be closed? if the latter, are the closures currently operable?

If the pipes are open, I suppose that the difference between the torus and drywell pressures should be proportional to the difference in the two water levels, (a) inside the torus, and (b) inside the drywell and pipes. Is that correct?

Jorge: All I know is that heat rises and in this containment concept it is expect that over-pressure contaminates travel down to get scrubbed in water then remaining gas borne contaminates travel through entrapment filters before exposure to the environment (needs electricity to perform this function). This concept is ***-backwards. Due to its massive size, you'll have pressure differentials just from height measured from the torus water level to the upper part of the containment cap. I don't see how or why you would want to gate the 6 foot diameter pipe(s) leading to the torus as the pipe protrusions purposely violate the containment shell. When the system is failed it is measured as ambient.

I'm getting a headache but here is reading material that might answer your questions and a pic. Look and see where the weak points might be and remember just how large these contraptions really are.

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf"

 

[MadderDoc]

The Mysterious Green Box should be at least 6--7 m tall to match the height of the Mickey Mouse Ears. On the other hand, judging by the ground-level photo below, the Big Green Closet may be quite a bit taller than that. (The terrace is 17 meters above ground level.)

But, the Mysterious Green Box does not have to match the height of Mickey Mouse, nor the distance between his ears. Green Box was hung on the wall,
elevated from the base of the east wall, whereas you measure the height of Mickey Mouse from the base of the wall. And, when Green Box came off the wall it appears to have taken bits of the wall panel above it, off with it.

That Big Green Closet you are looking at, I can't see what it is, but I agree that it is much too tall to be the Mysterious Green Box. I thought you were looking at this more humble bit, at the foot of the wall.

 

[MadderDoc]

I thought I read TEPCO was doing a balancing act for SFP #4, trying to keep the weigh factor down with less water and their figures of re-watering were inline with boil off losses. So they allow the pond to get so hot but not to hot and still keep coverage over the fuel assemblies. In the meantime, they try to figure out if there is a leak or not. First there is then there isn't.

I am also not sure what the strategy is with this. Perhaps one cannot have a strategy in such a situation? If I have a kettle boiling on a stove which I cannot turn off, and I don't want it to boil, I may top it with cold water each time it starts boiling -- that cools it down, stops the boiling. But I risk ending up with a full, boiling kettle. After that there's only to pray for it to leak, so I can get to add more cold water and stop its boiling.

 

[mikefj40]

There is a bellows in the drain or vent lines between the DW & SC.

The torus cutaway shows the bellows. Page 35 of this deck. http://fairewinds.com/content/how-did-general-electric-ge-mark-1-bwr-reactors-end-creating-such-world-wide-tragedy