Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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

.

 

[Luca Bevil]

Actually the problems with the contaminated water processing equipment are much more serious than anticipated.

http://www3.nhk.or.jp/daily/english/12_09.html

nothing to be happy or confident about

 

[westfield]

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.

http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/temp.html"

http://i1185.photobucket.com/albums/z360/fukuwest/misc/Unit4Thermalinctable.jpg"

 

[tsutsuji]

Actually the problems with the contaminated water processing equipment are much more serious than anticipated.

http://www3.nhk.or.jp/daily/english/12_09.html

nothing to be happy or confident about

Only 0.5 tons per hour instead of the expected 12 tons per hour is flowing in one of the four units. A pipe is clogged or a valve is failing to open. The test run is postponed to tomorrow. The launch of the facility expected on June 17th or 18th : http://www.asahi.com/national/update/0612/TKY201106120141.html

 

[joewein]

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?

No it shouldn't. You're looking at the warm water below through the remaining steel lattice of the roof structure of unit 4. The smaller and larger steel beams are cooler than the water below:

[PLAIN]http://img535.imageshack.us/img535/3165/gggss.png

Likewise, the purple zone between the red zone highlighted by the arrow and the circle is the crane structure above the fuel pool, which obstructs most of its thermal footprint. You tend to get sharper heat signatures at the edge of the building (arrow and bottom left corner), where steam escapes sideways through the blown out walls.

If you feel like studying more thermal images of unit 4, there's a whole bunch of them on the Ministry of Defence website, from March 20 to April 26:
http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/temp.html

Look for "第4号炉" for the unit 4 thermal images. On these images the pool area almost always comes out as the warmest part of the building, warmer than the reactor well in the center, just as expected.

 

[elektrownik]

On these images the pool area almost always comes out as the warmest part of the building, warmer than the reactor well in the center, just as expected.

NO, for example 4/20 sfp 18, core 29; 3/23 sfp 22, core 28;
We can see from scale that it temperature was bigger many times...

 

[ManuBZH]

Actually the problems with the contaminated water processing equipment are much more serious than anticipated.

http://www3.nhk.or.jp/daily/english/12_09.html

nothing to be happy or confident about

Nothing to be overly pessimistic about neither. Looking at the sheer size and complexity of the facility (and the incredibly fast construction time which is already a feat in itself), this is no surprise that they run into some problems.

We can only wait and hope that the whole thing will work as advertised and, once started, won't run into serious issues.

 

[joewein]

It sounds like they have problems with one of 4 units, each of which is designed to handle 300 t per day. If the other three units work as expected they would still be able to process 900 t per day, more than the 500 t they use for cooling each day.

It would be far more worrying if problems like these happened once they're using the system for processing highly contaminated water and not during trial runs with plain water or lowly contaminated water.

It's far preferable to encounter and solve the problems now rather than later.

 

[swl]

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.

Unfortunately, the indicated temperature will be effected by the emissivity coefficient of each surface being measured. For example, if our iron bar in your example is polished on one end and rough finished on the other, there will be a huge difference in the IR emission detected. The emissivity coefficient will vary with both the surface finish and the type of material.

 

[etudiant]

It sounds like they have problems with one of 4 units, each of which is designed to handle 300 t per day. If the other three units work as expected they would still be able to process 900 t per day, more than the 500 t they use for cooling each day.

It would be far more worrying if problems like these happened once they're using the system for processing highly contaminated water and not during trial runs with plain water or lowly contaminated water.

It's far preferable to encounter and solve the problems now rather than later.

This testing is what a shakedown is there for. The only problem is the overwhelming time pressure.
Unfortunately, the Kurion cesium removal is in a sequential arrangement with the other modules, so it is now gating the throughput until the source of this blockage is found.
Hopefully, the testing is just done with water, so the testing can be done freely, without needing to take extra precautions because of radioactivity.

 

[causeceleb]

Unfortunately, the indicated temperature will be effected by the emissivity coefficient of each surface being measured. For example, if our iron bar in your example is polished on one end and rough finished on the other, there will be a huge difference in the IR emission detected. The emissivity coefficient will vary with both the surface finish and the type of material.

it seems to me that you all are talking about ancient history.
aren't we presently dealing with 3 or more distinct total meltdowns?
and doesn't "meltdown" imply "corium"? and doesn't "corium" imply
temperatures in excess of 3000 degrees Fahrenheit?

if this is the case, then how do any of these current fact bare on the state of the present
situation at Fukushima?

 

[Bioengineer01]

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.

I am afraid that my experiences are from the health care industry (21+ years) and are mostly derived from conversations with actual regulators in charge of writing the stuff. And even in one instance from a presentation given to engineers by an ex director of the FDA where he told us that directly. I don't have the time to go search the nuclear regulations for examples. Also in the USA things may be different between medical devices and nuclear in terms of safety regulators behavior. I saw an example that suggests that nuclear in the usa may be different and much more lenient to industry. That is Emergency plans. The law stated in the code of federal regulations, nuclear is part 10; 10 CFR, part 100 (reactor site criteria, chapter 11 emergency planning). The law establishes 1 criteria, nobody in the population should get more than 25 REM of radiation during the course of a nuclear accident. The law doesn't specify the distance, just that the population needs to stay below 25 REM exposure no matter what. Now the regulators that need to implement the law make assumptions that are very lenient for the worst case, they assume to create the NEWREGs (0654 and 0396) that the worst case is 1% of fuel failure, that 95% of that failed fuel gets stuck in the containment, and that the 5% of 1% (0.05%) is released at 1/2% per day to come up with the emergency evacuation zone. Also the emergency plans make a lot of assumptions about the status of the infrastructure and the behavior of the people involved that are not realistic. This ends up with small evacuation zones (10 miles), relatively simple and achievable plans (in paper) that are very favorable to industry. In medical devices, it is quite different, if there is a significant problem, no matter what industry did, the regulations are such that the FDA will always be able to find something you did wrong.

 

[tsutsuji]

It sounds like they have problems with one of 4 units, each of which is designed to handle 300 t per day. If the other three units work as expected they would still be able to process 900 t per day, more than the 500 t they use for cooling each day.

That unit has been tested again today after checking the valves and the water flow was found to be OK, although the exact cause of the problem is not clear. The test with low level contaminated water starts tomorrow. The initial plan is to run the test for 5 days but that could be shortened : http://www.asahi.com/national/update/0612/TKY201106120177.html

Taking into account additional contaminated water storing capacity secured at the unit 1 condenser or at the high temperature incinerator 2nd basement, the expected date of overflow is postponed to June 27th : http://www.nikkei.com/news/headline...19595E3E0E2E2E38DE3E0E2E4E0E2E3E3E2E2E2E2E2E2

 

[clancy688]

if this is the case, then how do any of these current fact bare on the state of the present
situation at Fukushima?

They're talking about the IR image of Unit 4. The meltdowns occurred in Units 1-3. Probably no meltdown in Unit 4.

 

[Bioengineer01]

Nothing to be overly pessimistic about neither. Looking at the sheer size and complexity of the facility (and the incredibly fast construction time which is already a feat in itself), this is no surprise that they run into some problems.

We can only wait and hope that the whole thing will work as advertised and, once started, won't run into serious issues.

After somebody told me that the news I posted was NO NEWS... I only wanted to reflect on the status of the project... My project experience also suggests that they were going to run into "expected" problems... but what we don't know is how the schedule was constructed, was June 15th the best date, the expected date or worst case... Now we know it was not the worst case... I am willing to bet based on running this type of level of complexity projects that the expected date is somewhere after end of June and June 15th was shortest possible date if NOTHING went wrong (something that only a PR or an administrator could think). Don't want to speculate on worst date...

 

[Bioengineer01]

They're talking about the IR image of Unit 4. The meltdowns occurred in Units 1-3. Probably no meltdown in Unit 4.

This discussion reflects on the poor credibility record laid out by TEPCO, any apparent inconsistency needs to be explored to the limit to be sure we understand what is happening and the thermal images of Unit 4 have shown the inconsistency of higher temperatures at the site of the RPV/PCV for a long time. I could point to lots of conspiracy theories created around that inconsistency. The witness testimonies of the presence of the JDF at the time of the explosion of Unit 3, aired on live TV and then captured by very few written news sources, and most later taken down from the net, do not help either.

 

[zapperzero]

the NEWREGs (0654 and 0396)

They are called NUREGs and they do recommend planning for the consideration of a 10-mile zone for immediate evacuation or sheltering in place, regardless of accident size.

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0396/sr0396.pdf
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0654/r1/sr0654r1.pdf

0396 specifically states:
"The task force does not recommend that massive emergency preparedness programs be established around all nuclear power plants" (underlining is not mine, it appears in the original text). while 0654 revision 1 contains such delightful examples of wishful thinking as
"the size of the ingested exposure EPZ (about 50 miles in radius) was selected because [..blah blah other reasons here..] there may be conversion of atmospheric iodine [...] to chemical forms that do not readily enter the ingestion pathway"

I will note in passing that both NUREGs are in PDF format, but the PDFs do not contain text, but rather scans of typewritten pages. Of course, such a format is not searchable or indexable. I do not understand why this is so.

EDIT: NUREG 0396 is dated 1978. It's quite surprising to me that it has not been amended in any way, after TMI and Chernobyl. I suppose nothing was learned since?

 

[Jorge Stolfi]

Unfortunately, the indicated temperature will be effected by the emissivity coefficient of each surface being measured.

Does anyone know how the temperatures are measurd by the IR imaging equipment?

AFAIK, astronomers measure the intensity of the IR radiation at several wavelengths, and infer the temperature of the source from the ratios between those intensities. That allows them to compensate in part for emissivity coefficients, unknown distances and absorption by any cooler stuff that may lie along the line of sight. It is like a blacksmith evaluating the temperature of a hot iron by its color, which (unlike the brightness) does not depend on the status of the surface. But astronomers usually obtain this data by taking separate monochromatic images through different filters.

Are the temperatures in the Fukushima IR images measured by the same principle? I do not know whether there are IR cameras that can take snapshots in two or more wavelengths at the same time (i.e. "color IR" pictures; and the multiple-filter method seems rather awkward for military use.

Could it be that they are using monochromatic IR images, and inferring the temperature from the intensity alone? That method should work in known environments (such as for monitoring equipment in a plant). It may also work for military analysis of aerial images, where it may be enough to detect warm spots, with only crude estimates of temperature based on distance and ambient temperature. But I can imagine many complications in the case of the Fukushima Daiichi images, including the presence of debris over the pools and condensed (hence cooler) "steam" clouds above the reactors. In any case it seems to me that a temperature scale based on IR brightness alone would be an "educated guess" at best.

 

[Jorge Stolfi]

I will note in passing that both NUREGs are in PDF format, but the PDFs do not contain text, but rather scans of typewritten pages. Of course, such a format is not searchable or indexable. I do not understand why this is so.

Because Postscript was developed only in the late 1980s, and became reasonably popular only in the next decade. Therefore much of the literature before 1990 is available only on paper or microfilm, and the only reliable way to digitalize it (including diagrams and subtle typographic details) is in the raster image format.

One can run an OCR on those images to obtain also a text repesentation that can be searched and copy-pasted, and include it in the PDF file so as to imitate some the functionality of true PDF format. Technical journals have been doing that with their past issues, and Google was doing the same with old books and magazines from libraries. However the OCR output one gets from old print is not so good, and it takes a lot of manual editing to make it usable for searching.

 

[westfield]

Does anyone know how the temperatures are measurd by the IR imaging equipment?

snip .

For those interested, "NEC \ AVIO" cameras are mentioned in the documents, http://www.nec-avio.co.jp/en/products/ir-thermo/"

 

[westfield]

This story is of precisely zero importance.

snip .

Well this is a physics forum not a psychics forum, we still need to hear about it ;)

 

[jim hardy]

The few IR cameras i ever used had a knob on the side labelled "Emissivity" and when you turned it it changed all the reported temperatures.

So I take IR pictures to be a relative measurement showing approximate distribution of heat, not like a thermometer showing true temperature.

Emissivity is something's affiinity for giving off heat via radiation.

That's why a Franklin stove is flat black(higly emissive) and the inside of a Thermos bottle is silvery white so as to not radiate well.
Everything else is in-between.

I have no idea whether liquid water is transparent or opaque to IR, or in between. So those IR cameras could be showing me either the surface of the water or the bottom of the pool, and i'd defer that pronouncement to somebody who does know .

 

[radio_guy]

I still hold the view that using IR/thermal imagery from a closer distance could give them a better picture of where the core debris is located and they could possibly modify the cooling plan based on it's location. maybe an on site set of images from different angles could give enough perspective into what they are really dealing with, it could also be used to pinpoint leaks and help them with at least having a better idea of the current failure modes.

I don't know about any of you, but if I was the plant operator and was applying cooling and making plans on a best educated guess I would be looking for ANY other form of information other than "this seems to be working for now, let's keep doing it" right now from what I am reading is they are working on a system of action-reaction, change something and see what happens then base changes on that.

 

[ceebs]

Here it is: http://www.tepco.co.jp/cc/press/betu11_j/images/110603a.pdf (page 8)

Out of the 720k TBq, 140 TBq account for C137. A little comparison: The Chernobyl core had a total C137 inventory of 280 TBq (of which only 40% escaped).

So is that saying there's more C137 in that trench, than escaped from Chernobyl?

 

[Atomfritz]

I will note in passing that both NUREGs are in PDF format, but the PDFs do not contain text, but rather scans of typewritten pages. Of course, such a format is not searchable or indexable. I do not understand why this is so.

EDIT: NUREG 0396 is dated 1978. It's quite surprising to me that it has not been amended in any way, after TMI and Chernobyl. I suppose nothing was learned since?

One can run an OCR on those images to obtain also a text repesentation that can be searched and copy-pasted, and include it in the PDF file so as to imitate some the functionality of true PDF format. Technical journals have been doing that with their past issues, and Google was doing the same with old books and magazines from libraries. However the OCR output one gets from old print is not so good, and it takes a lot of manual editing to make it usable for searching.

Some things aren't being OCRed in the public versions.
Too many curious people could find things that some do not want to be public.
Just a quite obvious example:

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.

I don't have the time to go search the nuclear regulations for examples.

Just let's take a document written on a word processor as example.
A document that's origin is digital (not typewriter!) and is probably stored fulltext in the NRC databases.

But for the public it has been printed out and then scanned as image to be published as non-indexable (and so non-googleable!) PDF.

This document is called "NUREG CR/5969" (thanks to the guy who recently posted a http://www.ornl.gov/info/reports/1992/3445603689514.pdf" to!).
It deals with strategies to avoid/mitigate severe BWR accidents.
In the section discussing recriticality issues and weaknesses of some boron injection systems you read on page 59, regarding suggested safety upgrades:
"However, this would require significant modifications to existing equipment and this would be beyond the scope of the present study."

In clear text this means:
"It would cost the reactor industry money to make sure that this recriticality issue is resolved.
So this is a no-no, and we won't discuss this issue."

Just one of a plethora of examples.

 

[jmelson]

d

I have no idea whether liquid water is transparent or opaque to IR, or in between. So those IR cameras could be showing me either the surface of the water or the bottom of the pool, and i'd defer that pronouncement to somebody who does know .

A few hundred feet of moist air can absorb a lot of thermal IR. Pools of liquid water will certainly
absorb ALL thermal IR, so you can only read the temperature of the surface of the pool.

Jon