Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Bioengineer01]

Reactor 3 Bldg RadiationSource: TEPCO press conference June 10.

5 TEPCO employees, 4 from affiliate companies entered the reactor building to prepare for nitrogen injection into Containment Vessel. In 30 minutes, surveying ~half the floor, got exposed to 5.88 to 7.98 millisieverts

96 millisieverts/hour radiation at the staircase going down to the basement, at the southwest corner blue print at llink.
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-reactor-3-bldg_10.html

 

[etudiant]

More than warming not heeded, the explanation is different, it is a common regulatory practice, even in the USA of not defining in hard numbers the limits when those are known to be too high due to cost considerations and leaving the decision making to Industry, fully knowing that they will be forced to compromise. The problem with NP is that the final liability is taken by taxpayers, differently from other industries.

Interesting insight into the regulatory system. Illustrates the process of regulatory capture to perfection.
If imposing the proper standard would kill the project, (as well as the need for the regulators), just fuzz the requirement to what is commercially viable.
Also interesting that the final liability is with the taxpayer no matter what the regulatory structure. Japan has no Price-Anderson Act, but the government is paying compensation for the TEPCO accident anyways.

 

[thehammer2]

"TEPCO did the test run of the contaminated water processing facility by Areva at Fukushima I Nuclear Power Plant, and found leaks in more than 10 places."
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-system.html

This story is of precisely zero importance.

In the process and related industries, when a unit is new/repaired/modified/etc., one of the things you do is to run a hydrostatic test with just plain water (or a compatible fluid if water is not compatible with the process going on inside the unit). This test is SUPPOSED to find the leaks and all the little gremlins in the system. You run the test, you fix what you find, and you repeat until you run the test and the system holds. Then, you introduce the process to the system. It's how you ensure that what's supposed to be on the inside stays on the inside and what's supposed to be on the outside stays on the outside.

Nuclear is just a process industry with WAY more rules. This is completely normal in a new unit or process.

 

[Quim]

I would agree so far, except ...the RPV had been breached several hours earlier......

No matter Jorge, as long as we are in agreement that there was a path between the RPV and the drywell we have no differences here.

There may be some confusion here. AFAIK the concrete shield plugs are meant to block radiation only, not pressure. They may be octagonal in other reactors, but in #2--#4 all drawings indicate that the opening of the refueling pit is round and the plugs are three disks, 1--2 feet thick, each cut into two halves (presumably so that they can be more easily moved and stacked on the cramped service floor). AFAIK those plugs are held in place only by their weight.

This is another trivial divergence, but I was under the impression that the original GE design had a round hole at the top and at Fukushima they had used an octagonal design - I probably got this from T-Cups' post #649 on page 41.

There were a number of design considerations for the secondary containment structure; it was meant to shield radiation, but it was also meant to be able to ward off at least medium sized aircraft or debris from tornadoes etc.

Another of it's qualities obviously was to seal the drywell from the rest of the building (which was at a negative pressure.)

In an earlier post it was disclosed that a GE mark I had been subjected to a real life pressure test and it had leaked at something like 60 psi. The report or the post about that implied that it had "failed" at 60 psi.

When I said that the Fukushima design may have held to 125 psi I was trying to avoid that apparently controversial subject, but it appears that I found another aspect to be controversial about.

Sorry for the lack of detail.

At those temperatures and pressures, any oxygen that remained in the drywell from before the breach or that was generated by radiolysis/thermolysys should have been promptly consumed by the excess hydrogen, before it could buid up to an explosive concentration. But maybe not.

This point lies at the heart of the matter IMO and I would love for one of our forum chemists (or physicists) to chime in with an opinion.

When I describe "flashovers" I believe I am describing the exact process described by "(oxygen)should have been promptly consumed by the excess hydrogen"

I did not do the math, but pesumably a massive leak of steam at 60 psi (400 kPa) into the refueling pit could have lifted the shield plugs, enough to let that steam escape into the service storey --- unless it found some easier way out.

What I was attempting to describe is a process whereby hydrogen had been seeping out of containment and was building up in the building above before any "massive leak of (hydrogen laden) steam" occurred.

However, I do not see how a sudden reduction in pressure (which would have cooled the steam) could have caused it to explode. Everything I see in the wreck suggests that the explosion happened some time after the H2 began to escape -- enough time for it to flow down to the 4th and 3rd storeys and mix with the air. I would rather believe that the steam leaked ignited the colder H2+O2 mixture that was already there, just with for being hot.

Hydrogen is lighter than air, it would not flow "down."

According to the floorplans, he "cattle trough" that leads to the SFP (through which steam may be still leaking) is very narrow and short. The gate on the opposite side, to the dryer storage pool (through which steam is definitely still leaking) is as wide as the storage pool. I do not see either as being able to vector the steam significantly upwards.

But steam had been accumulating above the trough also. And I had hoped to be painting a picture of hydrogen accumulating in the trough before the explosion.

The head bolts *of the RPV* probably held fine, since the bottom had already been breached so the RPV was at ~400 kPa instead of its normal ~6500 kPa.

Again, I was just trying to head off what I see as an extraneous argument.
I probably should not have mentioned the headbolts.

But for this scenario we need a path for the steam to get from the drywell to the refueling pit.

I left off before the explosion had progressed that far.

Neither do I. I suppose that both gates (to the SFP and to DSP) were closed, and that there was no water in the SDP or in the refueling pit at the time of the explosion.

Well, we agreed on something!

 

[Atomfritz]

Neither do I. I suppose that both gates (to the SFP and to DSP) were closed, and that there was no water in the SDP or in the refueling pit at the time of the explosion.

Well, we agreed on something!

Maybe you are both wrong?

These seals are not watertight, as Christian Mueller explained in the document Joe linked at in his https://www.physicsforums.com/showpost.php?p=3350807&postcount=9598"?
Unclear yet is, how much water could leak when the inflated rubber seals lost their pressure when the compressor's electric supply failed?

The whole story is puzzling! I don't see any reason why they should have fuel in the RPV. But we see these hot spots. If it is water circulating between the RPV and the SFP why do we these delimited hot spots within the circle. Shouldn't the whole circle be an equally warm area? If it is from irradiated parts of the reactor then I can't believe that there is water in the RPV. How could parts get so hot when covered with water?

Maybe because water cools down in the RPV, compressing/getting more dense, and so the RPV as a heat sink sucks up the hot water circulating over from the SFP?
Sort like the gulf stream going north, being sucked to there by the cooling-down and falling water masses there?

Maybe there are some "interesting water dynamics" in the other reactors' pools also?

(Just the 2 cents of an annoying layman...)

 

[htf]

Well, but why are these spots in the RPV the hottest points on the whole image? If the RPV is full of water this would mean that there are powerful heat sources located at this place that can maintain a temperature gradient. Can irradiated reactor parts generate so much heat? I am not an expert but I hardly can imagine thas.

Or is the explanation quite simple: was the picture taken before the gates started leaking?

 

[jim hardy]

So are we looking down into the vessel with that IR photo, or are we seeing hot water & steam at surface of pool?

 

[triumph61]

http://ex-skf.blogspot.com/


"In the first photo, you can see the pipe that's bent. That was the pipe that TEPCO was counting on to connect the cooling system for the Spent Fuel Pool, according to Jiji News (6/11/2011). The cooling system for the Reactor 4 Spent Fuel Pool won't be operational at least until July, as TEPCO will have to either fix the pipe or come up with alternative connection.

The second photo shows a mess of broken pipes, concrete bits and equipments. Any mechanics, engineers, who want to dissect the photo?

The Reactor 4 was in a scheduled maintenance when the earthquake hit on March 11. All the fuel rods had been moved to the Spent Fuel Pool. The workers were in the process of replacing the stainless-steel shroud of the Reactor Pressure Vessel at the time of the earthquake."

That means: The RPV was empty, no Water in the RPV at the time of the Earthquake

 

[Quim]

Well, but why are these spots in the RPV the hottest points on the whole image? If the RPV is full of water this would mean that there are powerful heat sources located at this place that can maintain a temperature gradient. Can irradiated reactor parts generate so much heat? I am not an expert but I hardly can imagine thas.

Or is the explanation quite simple: was the picture taken before the gates started leaking?

As I understand it, unless you have calibrated the infrared camera to some standard of sensitivity and heat spectrum a photograph like that one is meaningless.

 

[Joe Neubarth]

http://ex-skf.blogspot.com/


"In the first photo, you can see the pipe that's bent. That was the pipe that TEPCO was counting on to connect the cooling system for the Spent Fuel Pool, according to Jiji News (6/11/2011). The cooling system for the Reactor 4 Spent Fuel Pool won't be operational at least until July, as TEPCO will have to either fix the pipe or come up with alternative connection.

The second photo shows a mess of broken pipes, concrete bits and equipments. Any mechanics, engineers, who want to dissect the photo?

The Reactor 4 was in a scheduled maintenance when the earthquake hit on March 11. All the fuel rods had been moved to the Spent Fuel Pool. The workers were in the process of replacing the stainless-steel shroud of the Reactor Pressure Vessel at the time of the earthquake."

That means: The RPV was empty, no Water in the RPV at the time of the Earthquake

But there could be debris in the reactor.

 

[thehammer2]

As I understand it, unless you have calibrated the infrared camera to some standard of sensitivity and heat spectrum a photograph like that one is meaningless.

Well, they will still show that there are temperature differences. You just won't know what those temperatures are or how large the temperature differences between the colors in the photos are.

Think of a piece of iron in a fire. When you pull it out, you can look at it and from the glow you can tell instantly that one end is hotter than the other. However, unless you have some special experience, you probably don't have any clue at all exactly how hot the glowing end is and you don't really know if the non-glowing end is cool or not. All you know is that the glowing part is hotter than the not glowing part.

Same basic idea.

 

[NUCENG]

More than warming not heeded, the explanation is different, it is a common regulatory practice, even in the USA of not defining in hard numbers the limits when those are known to be too high due to cost considerations and leaving the decision making to Industry, fully knowing that they will be forced to compromise. The problem with NP is that the final liability is taken by taxpayers, differently from other industries.

I would appreciate it if you could provide examples or references to that common regulatory practice. Maybe I shouldn't be so hard on Japanese regulators, if that is happening here.

 

[Quim]

Maybe you are both wrong?

Agrrrrrrhhhhh!


I've been trying my best to avoid being sidetracked into peripheral issues, I was just trying to lay the groundwork for a discussion of the #3 explosion.

I guess I need to go back and take some technical writing classes.

 

[NUCENG]

But there could be debris in the reactor.

Where from? the photos of SFP4 don't show that kind of damage. Perhaps through the small opening in the north wall of unit 4 when unit 3 exploded? I suppose that is remotely possible.

 

[robinson]

If only there was some way to get an image of what is inside the ruined buildings. Clearly the radioactivity is so high no camera can taker a picture of what is happening.

Or they would be snaking cameras on tubes inside the wreckage to at least try and find out what is happening.

 

[Quim]

Well, they will still show that there are temperature differences. You just won't know what those temperatures are or how large the temperature differences between the colors in the photos are.

Correct.

So a shift from yellow to red might mean a one degree change in temperature or a 100 degree change in temperature.

Maybe the racoon decided that the #4 RPV was the quietest place to take a nap and left a warm spot behind when he (or she) ran away at the approach of yet another photographer..

 

[Atomfritz]

Well, but why are these spots in the RPV the hottest points on the whole image? If the RPV is full of water this would mean that there are powerful heat sources located at this place that can maintain a temperature gradient. Can irradiated reactor parts generate so much heat? I am not an expert but I hardly can imagine thas.

Imagine the possibility that a bunch of relatively hot rods has been deposited dense-packed in the SFP just where the gate is.
Then water flowing thru this kind of "superheater" directly before the gate could be near steaming point, what could possibly explain the IR red.

Note: As the color/temperature calibration scale is not shown on the pic we cannot even for sure assume that the "red" spots are really "hot".
At least, the reported temperature of the SFP water of around 90 Celsius gives a hint about the probable scale range. Edit-add: Red could even be as low as 20 Celsius, but very probably less than 90 Celsius.

Now, if the gate is directly in front of the reactor hole, then maybe a layer of hot water from the gate accumulates where the reactor tube is, due to suction of falling water, because of cooling down and/or leaks?

Or is the explanation quite simple: was the picture taken before the gates started leaking?

The gates would be no longer watertight when the compressor stopped working (due to blackout) and the pressure in this kind of "tyre" had dissipated.
I don't know how much time it takes to become leaky because pressure got below critical point.

 

[NUCENG]

Correct.

So a shift from yellow to red might mean a one degree change in temperature or a 100 degree change in temperature.

Maybe the racoon decided that the #4 RPV was the quietest place to take a nap and left a warm spot behind when he (or she) ran away at the approach of yet another photographer..

Early on some of the thermal images had scales attached to the photos and full scale was only about 5 degrees. If we can find the source of the photos there may be more information.

 

[htf]

So a shift from yellow to red might mean a one degree change in temperature or a 100 degree change in temperature.

Of course, you can apply any colour scale you want. If Tepco is not totally crazy or intends to fool the rest of the world then they will at lest have applied a scale where "blue" means colder than "red". Even if the camera was not calibrated and the colour scale is unknown we can conclude that there are spots in the RPV that are hotter than the SFP. And we know that the SFP is close to 100°C.

 

[Jorge Stolfi]

Another of it's qualities obviously was to seal the drywell from the rest of the building (which was at a negative pressure.)

There may be some confusion here. The drywell is hermetically closed by the bellows seal (that spans the gap between the drywell's neck and the lower flange at the top of the RPV) and then by the big yellow drywell cap (that is bolted to the drywell's mouth).

I believe that the only purpose of the bellows seal is to allow the refueling pit to be flooded without flooding the drywell. I guess that the bellows seal is the weaker of the two, and that the drywell cap must be in place while the reactor is operating. Is this correct?

AFAIK, the concrete layer around the drywell (including the plugs of the refueling pit) is there only to protect the reactor against external impacts, and to absorb any gamma and neutron radiation that may have got through the drywell walls. It is not meant to contain radioactive gases; these should normally either remain in the drywell+torus or be vented through the external towers. In fact, the concrete enclosure has eight truck-wide openings at the bottom, to accommodate the pipes that connect the drywell to the torus.

In an earlier post it was disclosed that a GE mark I had been subjected to a real life pressure test and it had leaked at something like 60 psi. The report or the post about that implied that it had "failed" at 60 psi.

Again you may be confusing the inner vessel (RPV), that operates at ~7 MPa (70 bar, 1000 psi) and is tested with over 10 MPa (100 bar, 1500 psi); and the outer vessel (drywell + pipes + torus), that is normally at low (negative?) pressure, and is designed to hold only to ~500 kPa (5 bar, 75 psi). IIRC that test you mention was about the latter.

When I describe "flashovers" I believe I am describing the exact process described by "(oxygen)should have been promptly consumed by the excess hydrogen".

What I mean is that the oxygen does not even get to form really. Basically, under the conditions at the time I would expect to have only water+metals --> H2+oxides, with no free oxygen. However the chemistry of corium seems to be incredibly complex, so perhaps the oxides decompose when it gets hot enough.

(BTW, another intersting detail I got from that documentary on the construction of Fukushima Daiichi is that the RPV is not made of stainless steel, but only clad with it. That explains the fuss about saltwater ruining the reactor.)

Hydrogen is lighter than air, it would not flow "down."

But, as a gas, it will readily mix with the air inside the service storey, which must have been anything but still. Whatever the source of the H2, the fresh gas entering that space could have pushed the H2+ais mixture down the many openings on the service floor.

On the other hand, if the source of the H2 was a leak on the drywell's wall, the H2 may have escaped also through the many openings in the concrete enclosure into any other floor including the basement. Hmm.

I had hoped to be painting a picture of hydrogen accumulating in the trough before the explosion.

That was my point: there is practically no space in the SFP trough, and on the opposite side there is no through at all.

Perhaps you are thinking of some pictures of other reactors that were posted here, showing a large separate pool between the refueling pit and the SFP. In all the drawings of #1--#4 that I have seen, there is no such pool; the SFP is right next to the refueling pit, and there is only a very narrow passage, no more than 2m wide and 3-4 m long, connecting the two.

 

[Quim]

we can conclude that there are spots in the RPV that are hotter than the SFP. And we know that the SFP is close to 100°C.

How can you conclude that?
The picture (with the red outline and x pattern) does not have the fuel pond in it.

I'm not trying to be picky, I just don't understand what information you get from that picture that I can't see.

 

[SteveElbows]

English Appendices Up for Japanese Govt Report to IAEA

All the appendices (appendixes?) are also available in English now.

http://www.kantei.go.jp/foreign/kan/topics/201106/iaea_houkokusho_e.html

Good stuff. So far I've been looking at attachments IV-1 and IV-2, as these provide english translation of the analysis that TEPCO did, and that NISA cross checked. These documents were the basis of interesting stories in recent weeks concerning how much fuel was damaged, possible timing and extent of containment damage, estimations of different substances released, and possible steam leak within reactor 3 HPCI. I already spoke of this stuff in the past because it was possible to understand some of the graphs and some paragraphs of the text. But now I can understand more clearly the picture they are painting, not much in the way or surprises so far but I will be picking on a few details for more discussion later.

Fo now I will just say that these documents make it very clear that they don't really know how well their analysis may match reality at the reactors, and they present several different scenarios for reactors in order to try to get a range of theoretical data to line up with the real data of unknown quality taht they have available. So for example with the hypothesis that reactor 3 HPIC may have released steam from the PCV to the outside, they base this on pressure data, they don't actually know if HPIC leaked.

 

[SteveElbows]

That means: The RPV was empty, no Water in the RPV at the time of the Earthquake

Official documentation, such as the recently translated attachments for the Japanese report to IAEA, say the following:

The reactor containment was under periodical inspection, so that all the fuel was removed, the MSIV was closed, and the well was filled with water.

Quote taken from last entry in table on page 20 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_3.pdf

 

[MiceAndMen]

Early on some of the thermal images had scales attached to the photos and full scale was only about 5 degrees. If we can find the source of the photos there may be more information.

They are here: http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/temp.html

 

[clancy688]

MSIV[/url]

What's a MSIV? The reactor cap? And what exactly is the "well" they're talking about?

 

[MiceAndMen]

What's a MSIV? The reactor cap? And what exactly is the "well" they're talking about?

Main Steam Isolation Valve
The hemispherical top of the Reactor Pressure Vessel (RPV)
The opening through the floor extending down into the RPV that is all flooded with water during refueling. My understanding is that there's a watertight bellows that covers the annular opening between the RPV and the Pressure Containment Vessel (PCV) during the times that the well is flooded.

 

[MiceAndMen]

Interesting insight into the regulatory system. Illustrates the process of regulatory capture to perfection.
If imposing the proper standard would kill the project, (as well as the need for the regulators), just fuzz the requirement to what is commercially viable.
Also interesting that the final liability is with the taxpayer no matter what the regulatory structure. Japan has no Price-Anderson Act, but the government is paying compensation for the TEPCO accident anyways.

You have summed up brilliantly the entire crux of the matter. Personally, I believe nuclear power can be built and operated with acceptable safety margins. Unfortunately, what constitutes "acceptable safety" is open to subjective interpretation. One may argue that the cost of appropriate and reliable safety systems is enough to make a NPP uneconomical to build and operate. The nuclear power industry has been making that argument forever, and the regulators try to be acommodating.

As for the Price-Anderson Act, it ensures that General Electric* and the US NPP owners will get to stay in business after a worst-case accident. In TEPCO's case, they will be out of business and the shareholders will be left with nothing of value. Price-Anderson is a potent piece of evidence that the nuclear power industry in the US is economically unable to support itself. It is a key part of government policy - and has been for many decades - that ensures that profits are privatized while the risk is socialized. IMO it should be repealed and then the utilities can make clear decisions about whether or not they wish their shareholders to be wiped out in the event of a major accident. Either way, the taxpayers will remain on the hook. Price-Anderson simply gives the owners a Get Out Of Jail Free card, and I don't trust people to make safety judgement calls when they've got a parachute but nobody else does.

I want this industry to grow and thrive, but Price-Anderson is an impediment to that IMO. It makes decisions to compromise on safety all too easy.

And anything more than that probably belongs in the other thread, so that's all I'll say about it here.

*GE, Westinghouse, Babcock & Wilcox etc

 

[Quim]

There may be some confusion here. The drywell is hermetically closed by the bellows seal (that spans the gap between the drywell's neck and the lower flange at the top of the RPV) and then by the big yellow drywell cap (that is bolted to the drywell's mouth).

I believe that the only purpose of the bellows seal is to allow the refueling pit to be flooded without flooding the drywell. I guess that the bellows seal is the weaker of the two, and that the drywell cap must be in place while the reactor is operating. Is this correct?

AFAIK, the concrete layer around the drywell (including the plugs of the refueling pit) is there only to protect the reactor against external impacts, and to absorb any gamma and neutron radiation that may have got through the drywell walls. It is not meant to contain radioactive gases; these should normally either remain in the drywell+torus or be vented through the external towers. In fact, the concrete enclosure has eight truck-wide openings at the bottom, to accommodate the pipes that connect the drywell to the torus.

Again you may be confusing the inner vessel (RPV), that operates at ~7 MPa (70 bar, 1000 psi) and is tested with over 10 MPa (100 bar, 1500 psi); and the outer vessel (drywell + pipes + torus), that is normally at low (negative?) pressure, and is designed to hold only to ~500 kPa (5 bar, 75 psi). IIRC that test you mention was about the latter.

What I mean is that the oxygen does not even get to form really. Basically, under the conditions at the time I would expect to have only water+metals --> H2+oxides, with no free oxygen. However the chemistry of corium seems to be incredibly complex, so perhaps the oxides decompose when it gets hot enough.

(BTW, another intersting detail I got from that documentary on the construction of Fukushima Daiichi is that the RPV is not made of stainless steel, but only clad with it. That explains the fuss about saltwater ruining the reactor.)

But, as a gas, it will readily mix with the air inside the service storey, which must have been anything but still. Whatever the source of the H2, the fresh gas entering that space could have pushed the H2+ais mixture down the many openings on the service floor.

On the other hand, if the source of the H2 was a leak on the drywell's wall, the H2 may have escaped also through the many openings in the concrete enclosure into any other floor including the basement. Hmm.

That was my point: there is practically no space in the SFP trough, and on the opposite side there is no through at all.

Perhaps you are thinking of some pictures of other reactors that were posted here, showing a large separate pool between the refueling pit and the SFP. In all the drawings of #1--#4 that I have seen, there is no such pool; the SFP is right next to the refueling pit, and there is only a very narrow passage, no more than 2m wide and 3-4 m long, connecting the two.

No I am not confusing the RPV with the drywell. However in looking back at some earlier posts I can see that it was postulated by someone that the bolts holding the drywell cap may have stretched - and at the thought of "stretched bolts" I assumed they were talking about the RPV. But as I look back I see that there really was a hypothesis that the < 125psi pressure had stretched some bolts. I had discarded the bolt stretching hypothesis for the RPV and I certainly wouldn't entertain it for the drywell cap.

Some of this confusion may stem from that, plus the fact that I inappropriately bundled the area above the drywell cap, but under the concrete lid structure as "the drywell" when it is a distinct, yet unnamed (to my knowledge), space.

I saw (and see) that space as being part of the drywell, I assume that it would have been at the same temperature and pressure as the regions below the yellow cap. The cap would not have contained the contents of the drywell , and I have read that the DW cap had a pressure release set at about 150 psi anyway. At the point in time I was attempting to describe, the drywell and the RPV were trying to reach equilibrium.

My OP in this string was meant to set up the probable conditions existing just before the jet of flame exploded out of the south end of building three.

But after this exchange I still have no idea how you see that instant of time and I'm afraid that I've been unable to communicate to you how I visualize it.

Maybe I'll try again later.

 

[htf]

How can you conclude that?
The picture (with the red outline and x pattern) does not have the fuel pond in it.

Now I am completely confused. I compared the image with the blueprints, counted the sections and got the impression that it shows the whole reactor building from the top with the circle marking the RPV. Is this not the case?

 

[SteveElbows]

Now I am completely confused. I compared the image with the blueprints, counted the sections and got the impression that it shows the whole reactor building from the top with the circle marking the RPV. Is this not the case?

It is the case, indeed the entire purpose of that composite image was to illustrate how the thermal image lines up with a picture of the entire building from above, and the reactor area. This includes the area above the fuel pool (although unlike reactor 3, there is a refuelling bridge obscuring much of the surface of the pool from direct overhead view). I've got no idea how Quim interprets the image differently.

In any case reviewing many of the thermal image documents that were linked to very recently is a good idea, gives a bit more of a balanced sense of what this area of reactor building 4 was shown to be like over time.

Personally I don't read too much into these images, the temperatures they suggested for pool 4 were probably not very good match to reality for a start. I find the theory that there is hot water in the reactor area to be quite reasonable, but generally reactor 4 does not interest me all that much at the moment, not compared to the other three anyway.

 

[tsutsuji]

"TEPCO did the test run of the contaminated water processing facility by Areva at Fukushima I Nuclear Power Plant, and found leaks in more than 10 places."
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-system.html

Also some trouble - a software bug ? was found with the automation controlling some 24 pumps pouring water in the cesium absorption facility. This will be repaired by June 12th early morning.

All in all the schedule is delayed for 2 days. The test of the facility that was scheduled on June 10th is planned for June 12th. The launching of the facility is postponed to June 16th or 17th according to Asahi, 17th or 18th according to Mainichi.

http://www.asahi.com/national/update/0611/TKY201106110480.html
http://mainichi.jp/select/weathernews/news/20110612ddm008040075000c.html

 

[etudiant]

Also some trouble - a software bug ? was found with the automation controlling some 24 pumps pouring water in the cesium absorption facility. This will be repaired by June 12th early morning.

All in all the schedule is delayed for 2 days. The test of the facility that was scheduled on June 10th is planned for June 12th. The launching of the facility is postponed to June 16th or 17th according to Asahi, 17th or 18th according to Mainichi.

http://www.asahi.com/national/update/0611/TKY201106110480.html
http://mainichi.jp/select/weathernews/news/20110612ddm008040075000c.html

While furious because of TEPCOs role in creating this disaster, one cannot but have respect for the extraordinary work that this represents, lashed up in a few weeks and expected to perform after a weeks shakedown. Whether the chemistry will work well enough no one knows, but they are trying.
Presumably the desperation alternative would be to create a massive radioactive water tank farm, using the infrastructure now getting set up.

 

[MiceAndMen]

"TEPCO did the test run of the contaminated water processing facility by Areva at Fukushima I Nuclear Power Plant, and found leaks in more than 10 places."
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-system.html

As others have pointed out, this is to be expected in a system like this that moves, literally, tons of water around. I would have been more concerned if they didn't find any leaks.

 

[Quim]

It is the case, indeed the entire purpose of that composite image was to illustrate how the thermal image lines up with a picture of the entire building from above, and the reactor area.

I am completely off today.

My apologies htf, I thought the camera was focused on top of the reactor chamber.

*turns off computer*

 

[tyroman]

The attachment is a diagram of the bellows seal for reference. The drywell cap is not shown for some reason. The "Vent Ducts" shown at the very top of the removable top shields (which cover the "Refueling Pool" during operation) has always been a curiosity to me.

For those who have not read this thread in its entirety, refer to my post on 4/30/2011:
https://www.physicsforums.com/showthread.php?p=3276801#post3276801
and read the DOE-leakage study concerning the BWR Mark I enclosure which is attached there.

The study predicted leakage paths and cross sections for various BWR enclosure types. I assume they concluded the bellows seal would fail first in order for drywell pressure to lift the cap...

I recall a previous post which described a "real life pressure test" wherein the normal PCV pressure test after a refuel failed below drywell design pressure due to unbalanced tourqes on the cap bolts. However, the study above looked at leakage during potential "upset" situations where design pressures are exceeded.

P.S. Source for the bellows seal diagram is a GJBRKS post on May 3:
https://www.physicsforums.com/showpost.php?p=3281660&postcount=5686

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