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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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Joe Neubarth
#4987
Apr26-11, 08:35 AM
P: 238
Quote Quote by jlduh View Post
The main interest of this video is that it shows clearly a phenomenon that has to be understood by anybody who wants to (try to) link measurements and risks for human health. It shows that in the very same area, measurements in microSv/h can HUGELY vary depending on how and where the measurement is done (and this is very often the origins of disputes between associations and autorities: meaning of measurements depending on how the measurement is done).

Which means that any measurement disclosed (also for the global measurements in the areas in the 20 or 30 kms areas) has to be taken as an indication but not a true picture of reality when trying to assess the mid or long term risks for human health (especially when trying to compare those to "thresholds" or "limits" or whatever).

A good part of contamination is related to dust particles carrying contamination, which will concentrate in geographical areas (leopards spots) and in one of such areas, there will be also a huge variability in places where particles will concentrate. The video shows for example that at the output of draining pipes from roofs, where particulates deposited with rain for example, the contamination concentrates. In a few meters distance, the levels can vary from one or several orders of magnitude.

The problem is that if you measure it at a level of let say 1-1,5m (your hands level) you'll get a measure very different than if you measure it at ground level, and at ground level, this measure will also widely vary depending on the spots. Everything that can move the particles is of factor of variation or concentration, and this can of course evolve with time: wind can relocate particles that were on the ground (so people can inhalate them), water will concentrate the dust all along its paths, etc.

The real exposition of a person living at a certain place for a given time will depend more on what he will do, breath, drink and eat, than on a global measured (but measured how?) value then extrapolated for a year, because this doesn't take into account the complexity of the processes involved.

In classical studies done for ongoing chemical pollutions out of many factories in their "normal" activities, the calculations done to assess the excess risks of cancers for example into one exposed population take into account a huge number of parameters, such as what people will eat and so on. And these will only give you a rough idea of some average exposition (that's why safety coefficient are put into place, to try to take into account the fact that measurements and dispersions are complex matters).

It is known for example that in the case of children, a major path for contamination to enter their body is through "ingestion of soil". This looks always surprising but not so much when you consider what they do during the day and also the fact that their mouth is not at the same level than ours as adults!
This info illustrates very well the point: http://www3.nhk.or.jp/daily/english/26_19.html

(even if this is maybe a "good" decision, it seems more a psychological related one than an effective one... because who can think of dust particles not moving from around with the wind and rain and redepositing?

This remembers me a lot of silly stuff done at Tchernobyl to try to fix contamination. Environment and contamination processes are somewhat different in essence than just the basic housekeeping cleanliness psychology: "this is dirty, this is clean"!

Ok, doing something is sometimes the only thing to do, so...

Hope this video and these explanations will help to understand the difficulty for REALLY assessing exposition risks for various people in a given area. Reality is always more complex than models and comparison of a number to an other number!
When I went through Naval NUclear Power school half a century ago, one of the first lessons we received in our "Hands On" reactor plant phase of training was that identical radiation detection devices could give you as much as a ten percent variance in readings from the same source at the same time. The counters were set up side by side, their probes were on a piece of white paper placed on an equidistant radius from the same source, but their readings were never identical.

Now, the sampling machines are probably greatly improved in the past half century, but I am still willing to bet that if the same test was run today there would still be considerable variance.
Samy24
#4988
Apr26-11, 08:35 AM
P: 56
http://www.tepco.co.jp/cc/press/betu...es/110426l.pdf

Yes, I know, it was hammered quite often. I-131/Cs ratio. This is after roughly 6 (I-131) half-lifes. I'm curious what someone will say after 10 half-lifes. Is it still some weird chemistry?
intric8
#4989
Apr26-11, 09:14 AM
P: 24
It does measure gamma, but a GM tube is not very sensitive to it. Most of it passes through it, without being registered.
The Radex specs state the upper range x/gamma detection at 1.25 mev which is more than adequate for cs137, but efficiencies are not stated. I've always wondered whether the manufacturers understand the limitations of their device and correct for the discrepancy, or kick out dose rates as is, in which case readings can be vastly understated.

The gamma component of cs decay is almost a heterogeneous flux at .6617mev. That's a high energy, though a certain amount of scatter occurs when these photons strike the glass wall of the gm tube. It's those photons with reduced energy that contribute to most of the reading. If not, many of these devices wouldn't register much at all.
AntonL
#4990
Apr26-11, 09:36 AM
P: 521
TEPCO to fill No.1 reactor with water http://www3.nhk.or.jp/daily/english/26_31.html

and less than 24 hours later

Nuke agency says water may be leaking from No. 1 reactor container http://english.kyodonews.jp/news/2011/04/87776.html

nothing changed the seesawing continues
MadderDoc
#4991
Apr26-11, 09:52 AM
MadderDoc's Avatar
P: 698
Quote Quote by Jorge Stolfi View Post
* The mysterious "hole" that appears in the pre-explosion photos is not in the 3rd row of panels from the top, but on the 4th. After the explosion, the hole got buried by debris; only the top edge is barely visible. <..>
By connecting corresponding spots of the wall deco on the north wall in post- and pre-explosion photos, taken from SW, it is possible to get some indication of the position of the 'hole' in relation to the pattern of that wall deco. The result of using this method indicates to me that the 'hole' does extend well into the 3rd.
MadderDoc
#4992
Apr26-11, 10:32 AM
MadderDoc's Avatar
P: 698
Quote Quote by rowmag View Post
Even worse, a lot of newer houses actually have active ventilation to prevent sick house syndrome. (May even be required by law.) But the fans can be turned off.
From this video:
http://www.youtube.com/watch?v=GZYAVeDhP5I
of Fukushima Daiichi plant, it can be seen that the 'windows' to the service floor of unit 1, 2, and 3 are relatively less insulating than the wall structure.
Nonetheless we know now that they actually would have liked some more active ventilation, to prevent these particular cases of sick house syndrome :-)

The video would seem to have been taken at about 22:30 in the evening after the earthquake and tsunami using a nighttime vision camera. It is in black and white and has the weird ghosty appearance one gets when shooting in infrared, then choose to invert the result such as to make it more visually appealing or similarly looking to daytime videos.

So, I reckon in this video darker is warmer, and brighter is colder.

The 'windows' aka easy blow out panels in the east walls of unit 1, 2 and 3 show up as dark spots on the walls. Unit 1 is distinctly different.
Jorge Stolfi
#4993
Apr26-11, 11:32 AM
P: 279
Quote Quote by MadderDoc View Post
By connecting corresponding spots of the wall deco on the north wall in post- and pre-explosion photos, taken from SW, it is possible to get some indication of the position of the 'hole' in relation to the pattern of that wall deco. The result of using this method indicates to me that the 'hole' does extend well into the 3rd.
Hey, here is another explanation for the "hole": actually two small holes leaking some dark fluid

rhody
#4994
Apr26-11, 11:39 AM
PF Gold
rhody's Avatar
P: 765
Lest we forget: Russian, Ukrainian Leaders Remember Chernobyl Accident , the aftermath, 25 years later...
Marking the first visit to Chernobyl by a Russian president, Medvedev called on the international community to work together toward unified nuclear safety guidelines to ensure that disasters like those at Chernobyl and Fukushima are not repeated.
and
The Chernobyl explosion released 400 times more radiation than the atomic bomb dropped on Hiroshima in 1945. It sent a cloud of radioactive fallout into Russia, Belarus and over a large portion of northern Europe.

The 1986 disaster has left a 30-kilometer area around the Chernobyl plant largely uninhabitable. Environmentalists any crops grown in the surrounding area could pose a threat to human health.

Thousands of sickened workers involved in the cleanup have protested in Kyiv against cuts in the benefits and compensation they receive for their exposure to radiation. They say their monthly pensions recently were cut, leaving them with barely enough money to pay for food and needed medication.

A donors conference in Kyiv last week raised more than $785 million, short of the $1.1 billion goal to build a new containment shell to replace the now-decaying original shell that was built over the damaged reactor.
The human and financial toll of it is still with us today.

Rhody...
mscharisma
#4995
Apr26-11, 11:59 AM
P: 82
Quote Quote by Borek View Post
This is tricky. The only way I can think about is to edit the very first post in the thread so that it contains kind of "executive summary" for the current situation/state of knowledge/list of known problems. That has to be done by one of the Mentors, as there is a limit to how long posts can be edited by their own authors.

I have no problems with doing the editing every few days, but the text has to be prepared by someone else. If anyone is ready and willing to do it, please contact me by PM.
I'm wondering (am good at that!) if a spreadsheet-like approach would be more feasible because it would be possible to search and sort if there were categories of issues, for example reactor #/general, date of issue/finding, exact question, possible answers, etc. Since the subject matter is in and of itself way beyond me, I don't know if this makes sense and if so, if it can be done in a way accessible to all of us?
AntonL
#4996
Apr26-11, 12:08 PM
P: 521
post No 5000 and the thread is in full swing
Bodge
#4997
Apr26-11, 12:25 PM
P: 145
How many posts will we have by December?

How will the RPVs, piping, drywells, reactor buildings and site personnel look by the end of the year?
mikefj40
#4998
Apr26-11, 12:27 PM
P: 26
This was posted today from Fairewinds. A 39 slide deck with photos I hadn't seen before. The cutaway of the Torus is impressive. http://fairewinds.com/content/how-di...d-wide-tragedy
Bandit127
#4999
Apr26-11, 12:31 PM
P: 186
Quote Quote by AntonL View Post
post No 5000 and the thread is in full swing
That's because the problems we are all trying to understand, and the enlightened are trying to help with, are still in full swing.

It will be 10 or 15 years before we get a BBC Horizon or Discovery Channel documentary that will fill in most of the basic facts for us (along with a lot of 'creative license' for those facts that will always be missing).

I suspect this thread might reach 50,000. Sadly.

Jim
dh87
#5000
Apr26-11, 12:43 PM
P: 39
Quote Quote by PietKuip View Post
I am saying that those readings are mostly beta radiation. It is not really correct to express the readings as a dose rate in sievert per hour.

With such meters it is easy to get readings that are much higher than the numbers given by authorities. That may undermine the confidence that the population has that the authorities are telling them the truth. But these are different instruments, and the official Japanese gamma dose rates can be relied on.

It seems that the conversion from countrate to dose is done for 300 keV gammas. That is also a bit crude, but it is the best that one can do with such a simple device. The real deviations occur when there is also beta radiation.
I am not sure that I understand what you're saying. For Cs-137, roughly half the energy is released as beta, and 100% of that energy would be absorbed if the beta hits a person. The Cs-137 gamma (from Ba) would also be absorbed, I think. For I-131, the energy spectrum is more skewed towards beta (about 2/3 of the released energy). To get the mSv dose, you'll need both the beta and gamma numbers. Either you need a device to do both, or you need to analyze the soil. In any case, as people have pointed out, the airborne material is at least as much of a concern as the material on the ground.
Cainnech
#5001
Apr26-11, 12:52 PM
P: 10
Regarding the "hole" - which really looks like a shadow.

Have you guys seen the green box at the same spot in this picture: http://cryptome.org/eyeball/daiichi-npp2/pict56.jpg
It's the last picture found at http://cryptome.org/eyeball/daiichi-...hi-photos2.htm.
In the downloadable zipfile (18.7MB) it is labeled 'aerial-2011-3-16-2-50-6'.
Attached Thumbnails
aerial-2011-3-16-2-50-6_2xb.jpg  
Jorge Stolfi
#5002
Apr26-11, 01:03 PM
P: 279
Quote Quote by Cainnech View Post
Regarding the "hole" - which really looks like a shadow.
Have you guys seen the green box at the same spot in this picture: http://cryptome.org/eyeball/daiichi-npp2/pict56.jpg
Hey, improving the previous theory: the green box is some external tank/radiator/pump. The earthquake (or the explosion from #3) knocked it off the wall. Some fluid oozing from the broken pipes created a stain that looks like a door with Mickey Mouse ears.
SteveElbows
#5003
Apr26-11, 01:05 PM
P: 630
Quote Quote by artax View Post
this map might give some explosion clues?

http://www.yomiuri.co.jp/dy/national/T110425003601.htm
Wowzers, 160 millisieverts per hour at one point of the hose between reactor 2 dodgy water and the waste treatment plant.

As for all this discussion about the dark area of reactor 4's east wall, if I look at the Oyster Creek reactor drawings that were linked to ages ago, there does seem to be a personnel airlock in that sort of area of the building. Granted the reactor buildings are not likely to be identical to Fukushima, but they seem similar in many respects. However from what I saw it seems quite possible that this personnel airlock is one level lower than the black mark, ie is got to through the 'office building' below, but I'm not 100% sure. But given ladders which I presume give access to the service floor also seem to be in the same corner of the building, it does seem reasonable to think this might be an access point to the building, especially given the external staircase leading up to this part of the building. Im not sure why I care that much about this though, given that it still looks a bit like a shadow to me, and that even if we do confirm it as being something, so what, what does it tell us?

Do we have any idea when humans last entered the service floor of reactor 2? We hear that humans arent going inside the main reactor buildings, but Im not sure if they count the service floor as slightly different? Would they have had to remove the blast panel from the inside? And how did they obtain the spent fuel pool/skimmer surge pool water sample from unit 2 without entering some part of the building? This leads me to wonder if humans still have access to that area.
Jorge Stolfi
#5004
Apr26-11, 01:15 PM
P: 279
Before someone blows away my neat explanation for the "hole", let me build further castles on top of it:

With the recent re-racking, the unloading of the reactor, and the arrival of new fuel, the heat generated in the #4 SFP overoloaded the existing coolers. So TEPCO installed a temporary extra SFP cooler outside the building (the green box). The earthquake knocked loose the cooler, and the water from the SFP started leaking out through the broken pipes. That is the "missing leak" in #4's SFP.


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