The paper by a Tokyo University researcher that was finally published nearly one year after he took the samples at the front gate of Fukushima I Nuclear Power Plant and in Iitate-mura in Fukushima Prefecture (see my post from yesterday) has this very interesting chart.
It shows the spacial dose of radiation at the front gate of Fukushima I Nuke Plant and the timeline of events at the plant in March. The largest spike seems to be around or after 12AM on March 15, and the label on the spike says "Dry vent at reactor no.2".
On checking the information from March 2011, I find that TEPCO did the dry vent at Reactor 2 at 12AM on March 15, 2011 for a few minutes. At first (on March 20), TEPCO announced they'd done the dry vent sometime on March 16 and 17, but on March 21 retracted that statement and said the dry vent was done at 12AM on March 15. (See Sankei Shinbun article on 3/21/2011.)
It is not clear whether the company informed the residents or the government before the the Reactor 2 dry vent on March 15 which caused a huge spike in radiation, and which may be the biggest contributor to radiation contamination in wide areas in Tohoku and Kanto. From the Sankei article it doesn't look like they gave any prior notice. This is the same company that didn't even tell the plant workers that the vent on Reactor 1 was about to be carried out on March 12.
Dry vent releases different types of radioactive materials compared to wet vent.
The peak that appears to the right side of the largest peak is after the hydrogen explosion of Reactor 4, but not at the time of explosion. I suspect the peak may have been the result of some event on Reactor 2's Suppression Chamber which seems to have taken place about the same time as the Reactor 4 hydrogen explosion. TEPCO says it was not "explosion" that happened at the Reactor 2 Suppression Chamber but still doesn't say what it was.
The second largest peak was when the fire broke out on Reactor 3 on March 16. The white smoke was seen at 8:30AM on March 16, and the radiation level at the front gate of the plant shot up to 10,000 microsieverts/hour (10 millisievert/hour) at 10:40AM (Asahi Shinbun 3/16/2011).
Again, it is just too bad that the researcher had to sit on the data for 11 months for his article to be published in a peer-review magazine.
30-Day free trial by following the link.
Tokyo Time
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35 comments:
Isn't this what professor Hayakawa's map indicated?
Dry vent is just releasing gas directly from the containment, without passing it through the pipes and the water in the suppression chamber, which can filter part of the isotopes.
About announcements and retractions from Tepco, something that happened around March 20-21 was that Tepco first announced a new venting because of high pressure in one of the reactors and some hours later claimed that "it was no longer necessary." Radiation levels went up like crazy all over Kanto anyway.
Why not go to all solar and wind, and some geothermal for baseload.
Simple, cheap, no evacuation zone
its 3 cents per kWH
modern semi safe nuke is going to cost 62 to 92 cents a kWH, and that does not include an allocation for disaster.
http://nukeproffesional.blogspot.com/p/renewable-and-energy-efficiency.html
Hi Ex-skf, If you read this could you let me know what you mean by 12AM? Does this mean midnight on the 14th? e.g. a few seconds after the start of the 15th day of March? Or a few seconds after the start of the 16th day of March?
I live in Japan and was traveling south around that time and I'd like to know so that I can figure out where I was at the time of the vent.
Thanks, and also thank you for all the useful news about the accident.
"Dry vent"? Is that some kind of synonym for "containment damage"?
According to the INPO report (pg. 21-28), Unit 2 was never vented because a rupture disk failed to break:
----------------------------
"At 2100 (T plus 78.2 hours), operators opened the small suppression chamber airoperated vent valve (AO-206), establishing the venting lineup (other than the rupture
disk). Indicated containment pressure remained slightly lower than the 62 psig (427 kPa
gauge) working pressure of the rupture disk, so venting did not occur. The vent valves
remained open, and operators monitored containment pressure.
[...]
Operators began to recognize some abnormalities in their indications. Containment
pressure was well above the rupture disk pressurebut the rupture disk had not failed.
Additionally, indicated drywell pressure was trending upward and had increased above
102 psia (0.7 MPa abs), whereas indicated suppression chamber pressure was stable at
about 43.5 to 58 psia (300-400 kPa abs), below the rupture disk pressure. The nonunified pressures indicated a problem. As indicated suppression chamber pressure was
lower than the working pressure of the rupture disk and indicated drywell pressure
increased above the design pressure, the operators decided to open the small air-operated
drywell vent valve (AO-208) to vent directly from the drywell to reduce pressure.
Two minutes after midnight on March 15, the operators opened the small air-operated
drywell vent valve (AO-208). The vent line lineup was complete, except for the rupture
disk that remained closed. Containment pressure remained stable at approximately 109
psia (750 kPa abs). The operators rechecked their lineup and found that the small airoperated drywell vent valve had already failed closed. They continued to work toward
establishing a containment vent path for Unit 2; but at about 0600 (T plus 87.2 hours), a
loud noise was heard in the area around the torus and suppression chamber pressure
indication failed low
[...]
Additionally, the suppression chamber
pressure reading 0.0 psia (0.0 MPa abs) is an indication of a failed instrument, not an
indication of atmospheric pressure. Indicated drywell pressure remained stable at
approximately 106 psia (0.73 MPa abs) and reactor water level indicated 110 inches
(2,800 mm) below TAF. The Unit 2 containment was not vented, and the cause for the
containment pressure changes has not been determined."
Moreover, you should check attachement 4-2 of the preliminary report:
http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_2.pdf
On page seven there's a table showing the releases of at least two dozen radioactive materials for each Unit. As for Cs137: Unit 1 released 5.9E14, Unit 3 released 8.2E14 and Unit 2 released, no brace yourself, 1.4E16.
There's a thread about this in PF I created back in June, but we didn't find a clue what may have caused this. Or why the japanese government seems to be so sure of that (otherwise they wouldn't publish those numbers, would they?)
http://physicsforums.com/showthread.php?t=507252
Good time to look back to find out what happened, understand the interdependencies, and learn the lessons, as now the initial confusion and anxiety has gone.
A very useful graphic to see most important officially announced parameters of reactor 2 can be found here:
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/out/plot-un2-t-I-full.png
(for more Fukushima graphs see here: http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/Main.html )
Looking at the chart and old press releases I try reconstructing things as far as I remember all the discussions I read about what went on:
(correct me please if I got something wrong)
Late at 3/14 the core started to become exposed.
It began to melt like a candle burning down, as the water level further decreased.
Some tube at the RPV cracked as maximum core pressure got exceeded, releasing steam into the drywell.
Pressure in the RPV decreased while the pressure in the drywell steadily increased.
Seawater injection started.
Water level in the RPV increased.
Pressure rose again, this time not only in the reactor pressure vessel, but in the containment, too.
Drywell pressure rose to the double design maximum.
So the containment was in danger to crack open and lose its function.
Late on 3/14 venting from the wetwell began.
However, wetwell pressure only slowly fell.
RPV and drywell pressure continued to rise because of sump clogging.
The sump clogging phenomenon prevented the wetwell working as a scrubber as intended.
So Tepco at midnight opened the drywell pressure release valves to avoid the containment blowing apart.
At least a dozen cubic meters of water violently boiled off and got vented as steam in a few minutes.
Plenty of steam satiated with radioactive isotopes and hot particles was released unscrubbed with high pressure this way.
Tepco was very happy that they had postponed the venting to night, as the steam escaped the vent stack at high pressure very violently.
This would have resulted in an extremely scaring scene transmitted worldwide by the webcams, showing ultra-radioactive steam shooting hundreds of meters high into air, resulting in a high plume that distributed contaminants over a very large area.
Lesson to be drawn:
The sump clogging phenomenon renders the sump/wetwell passive safety feature useless.
This affects practically all reactors that have a reactor sump, i.e. all light water reactors.
So it is deliberately overlooked by practically all nuclear regulations over the world.
Why this?
If one would take this phenomenon into consideration, one would have to admit that the safety systems that use the reactor sump have a high chance to fail in case of an accident.
And all reactor operation licenses worldwide depend on the assumption that the reactor sump will not clog.
@ anon 1:32 / clancy688
The "rupture disk failure" version can probably be discarded as an attempt to cover-up or to confuse.
There is just no plausible explanation except venting how the alleged official emissions could have left reactor 2.
It would be very improbable that these big quantities of contaminants were released through the torus crack, as first the reactor building would have been way more radioactive than it is, and second the whole area around reactor building 2 would then probably be a multi-sievert zone just from the condensates only.
Same applies to RB #2 floor 5. It's just not sufficiently radioactive there to have been the main release path.
However, the possibility of an intentional maneuvre to distract from other possible sources of releases as reactor 3 or SFP 4 should not be kept out of mind.
Nah, if they were trying to use reactor No. 2 to cover-up releases from other sources they would have prepared a better narrative than "we don't have a clue of what happened," which is basically what they are saying about reactor No.2 .
More and more people start to realize that they have to leave Fukushima
http://news.ninemsn.com.au/world/8430649/fukushima-residents-seek-immigration
Atomfritz,
Wasn't the blowout panel on #2 opened following the hydrogen explosion at #1 ?
Thanks so much for all your valuable work during this past year. I really appreciate... many people around the world cannot read Japanese so your input, feedback, translations, etc is much appreciated . THX SOOO MUcH!
BTW, have you got the chance to have a look at this Green-peas report? I wonder if they have it in Japanese too...
http://www.greenpeace.org/international/en/publications/Campaign-reports/Nuclear-reports/Lessons-from-Fukushima/
I got a question for you: Do you know anyone who is working to bring those responsible accountable? I mean seriously, not a joke, unlike an international tribunal, or citizen's movement...
Are there any suggestions, like creating re-education camps or hard labor in the nuclear plants for those responsible politicos.
What about those hiding information and denying the severity of this ongoing disaster?
People like Damashita, Ishihara, etc...
I recall reading that in old Japan people in high positions used to have something like a code of honor, where those who were responsible for a misdeed or mishap committed Sepuku to clean their misbehavior...
This passage of the INPO report illustrates the effect of the sump clogging:
"Additionally, indicated drywell pressure was trending upward and had increased above 102 psia (0.7 MPa abs), whereas indicated suppression chamber pressure was stable at about 43.5 to 58 psia (300-400 kPa abs), below the rupture disk pressure. The non-unified pressures indicated a problem."
This "problem" was sump clogging, and it's well understandable that they didn't name it explicitly.
The nuclear industry and "regulation" officially "solved" the sump clogging problem by increasing the strainer mesh diameter a bit so that smaller particles aren't filtered (which then in turn can cause other problems, like damaging the emergency cooling pumps, but just overlook this problem and all is fine).
But, as indirectly admitted in the INPO report, this didn't work out.
Now let's look at rupture disks in general:
INEEL states the following about rupture disk not opening failure mode in a document intended for probabilistic risk assessment:
"For rupture disks not opening when required, there is little published information.
One estimate of 1E-04/demand is reported in Cadwallader and Piet (1989). This value
seems reasonable, since the rupture disk is a simple component and it is intended to be
the weakest part of the wall area in a system, and the literature suggests that it generally
will rupture close to its bursting pressure. [...] Considering that many safety relief valves have 'failure to
open on demand' rates in the 1E-03 range, then it is reasonable that the simpler rupture
disk should have a lower failure rate. [...] Rupture disks are required to be able to burst within + 5% of
the design burst pressure [...]. The hydraulic design of the rupture
disks and the vent piping is a large safety concern, and must be approached with attention [...]."
( source: www.inl.gov/technicalpublications/Documents/3318080.pdf , page 12/13 )
Now let's turn back to the INPO report.
As seen, it is actually not very probable that the rupture disk didn't open.
There is no mention how they determined that the drywell rupture disk didn't open.
Without this information there is no way to check to what extent this statement about the rupture disk not working is true.
And, one has to be aware that the INPO report talks about two different rupture disks.
The containment (drywell) one with an working pressure of slightly above 460kPa.
The wetwell one with an working pressure of 427kPa.
If the sump hadn't been clogged, then the wetwell rupture disk would have opened automatically, initiating water-filtered venting.
Here a possibly very important quote from page 27 of the INPO report:
(upper case emphasization by me)
"Two minutes after midnight on March 15, the operators opened the SMALL air-operated drywell vent valve (AO-208). The vent line lineup was complete, except for the rupture disk that remained closed. Containment pressure remained stable at approximately 109 psia (750 kPa abs). The operators rechecked their lineup and found that the SMALL air-operated drywell vent valve had already failed closed."
If you read this closely and keep in mind the cause of sump clogging (insulation materials, glass fibers and so on, coming loose and clogging strainers in water/steam paths), then with the information made available then it could come in mind that actually the following scenario happened:
-Valve AO-208 was opened.
-The gas contents of the drywell were vented first.
-As the radioactive fission product gases were being "flushed", their volume was being replaced practically instantly by newly-produced steam from the almost white-glowing reactor fuel.
-After a few minutes of venting the small valve "failed". More precisely, either a strainer, some tube turns or the valve itself got clogged with the same materials that cause the sump clogging phenomenon.
This short period of gas venting (a few minutes) could then have been sufficient to purge the reactor and the containment from a large part of the gaseous (and some other) fission products, without changing the pressures significantly.
What would be the consequences of a clogging of the vent line?
It would mean that another foundation of the "safety concept" of light water reactors would be proven basically invalid.
This would affect all reactors, like the sump clogging.
So, admitting such a problem by the nuclear industry would mean admitting that the venting concept is basically flawed.
This would then affect all still-working reactors, because then the regulatory requirement of being able to vent wouldn't be met.
Consequence would be then, that all reactors would then be required to be shut down.
If my scenario is true, then it would be suicidal for the nuclear industry to admit the truth.
So they would be better off claiming an inexplicable failure of the rupture disk and just to not know where all the fission products mysteriously disappeared, just to purport: "we don't have a clue of what happened".
OT: I asked someone from Consumers Union Japan about food contamination and they seem to think it is no big deal.
---
1) If we start with the pdf link:
http://www.mhlw.go.jp/stf/houdou/2r98520000024bgm-att/2r98520000024bkb.pdf
You do know that the sign < means "less than" thus if it says <20 it means they have not detected any radioactive material above 20 Bequerel per kilogram. That is due to the way the detectors work. Most of them cannot detect very low levels with any certainty. Also, saying that "most food from the NE has radiation" makes no sense. After all the nuclear bomb testing done above ground in the US and USSR, and elsewhere, there is no "zero" anywhere on this planet. You do know that there is also cosmic rays and other "natural" radiation.
I agree that a food item around 500 Bequerel/kg is a bit high, and I would hesitate to eat it. That was a "provisional limit" set last year. But who eats a kilogram of anything? The new levels that are being introduced are in the range of 100 Bq/kg which is much more reasonable. CUJ has written about this on the English website:
http://www.nishoren.org/en/?p=1158
For example, in Sweden, the "safe level" for reindeer meat that is sold in supermarkets and restaurants is 1,500 Bequerel per kilogram.
2) In the second pdf link:
http://www.mhlw.go.jp/stf/houdou/2r98520000024bgm-att/2r98520000024bld.pdf
We can start looking at the data from Fukushima prefecture. They have so far tested 19,191 items, and found radioactivity above the 500 Bq/kg limit in 683 items, mostly in mushrooms and some fish. (Out of 1,847 grains they tested, they found 1 item of genmai rice and 1 item of wheat.) Those 683 items would not be for sale. No new items have been found recently.
For Ibaragi prefecture, they tested 11,928 items, and found radioactivity above the limit in only 85 items. No new items have been found recently.
For Gunma prefecture, the tested 10,329 items, and found radioactivity above the limit in only 26 items.
I think we do not need to get riled up about these figures. I'm not sure what you mean by "most food... sold and eaten as normal" when in fact, we are not seeing any high levels in the food in Japan. The data clearly shows that the situation is not a concern.
---
I find it very interesting that a consumer group would take such a sanguine view on this issue. Maybe they have been coopted,
I am so glad you don't have kids Mr Anom 6:58am. This topic is not about contaminated food. But it is not hard to find a relevant topic if you want to spew your ignorance.
"12AM on March 15" means midnight, or 0AM, when March 14 becomes March 15.
As to whether the vent was done or not, INPO report says it wasn't done, but the interim report by the accident investigation commission of the cabinet office in December last year says it was done, if only for a few minutes. They managed to create the vent line and hold the valve open for a few minutes. The pressure never reached the point where the rupture disk would break. From page 228, in Japanese only: http://icanps.go.jp/111226Honbun4Shou.pdf
"I am so glad you don't have kids Mr Anom 6:58am. This topic is not about contaminated food. "
I think you mean Mr. Anon 7:29 AM.
LaPrimavera, this is really intransparent, so many contradicting official statements.
Looked at the Japanese document you mentioned, using a translator, but the translation is really incomprehensible to me.
Really need to search for some schematics to understand better.
As the Japanese document states that the pressure never reached the working pressure of the rupture disk, does it mean the rupture disk of the D/w or the S/C?'
arevamirpal::laprimavera, I really hope you crack down on the off-topic posts being posted in this and in other news topics here. Seems that some of the idiot eco-nut commenters who spam off-topic posts over at ENENEWS have migrated here. You run a great blog. Please don't let it deteriorate like ENENEWS has.
@laprimavera @atomfritz, the English translation of the IC's interim report was released a while ago: http://icanps.go.jp/eng/
@anon at 3:20PM, thanks for the link.
So,
"At just past 00:00 on March 15, in the Units 1&2 main control room the recovery team
of the NPS ERC energized the solenoid valve for the small D/W vent valve (air-operated),
using compressed air from the portable compressor placed inside the truck bay door of the Unit 2 T/B, and constructed a PCV vent line (D/W side) except for the rupture disk.
However, within a few minutes they discovered that the small D/W vent valve (air-operated) was in the closed position."
D/W vent, for a few minutes. (page 268)
@anon at 7:29AM, consumer unions in Japan have been busy accusing consumers of punishing the producers too much by being picky. No surprise. They exist for the producers and the government, and their mission is to "educate" consumers.
I am very glad that you have picked up on the idea that reactor 2 may have been the major contributor to environmental contamination. There is much to discuss on this topic, and you may want to make further posts on this subject as there is quite a lot of other relevant data.
I will not try to cover everything with one comment, so for a start I shall look at other data showing rising radiation levels at various locations at various times on the 15th.
This site has some useful graphs covering the first month or so after the disaster. The graphs themselves are often not high enough resolution to get complete sense of timing, so check the raw data downloads that are available at the bottom of the page:
http://fleep.com/earthquake/
Note for example the rise in levels at Iwaki town hall between 1am and 4am on the 15th. The rise in levels in Tokyo at 4am, a larger rise over the period of 8am and 10am, and further rises between 5pm and 7pm. Note also a different pattern for a location thats in a different direction from the nuclear plant, Fukushima health office where readings lept up from 4pm onwards.
Combin this with what we know about how the wind changed direction in the period leading up to the 15th, and over the course of the 15th itself, and we start to get a picture.
Also worth pointing out that In the past, despite the original scary information that they thought the explosive sound came from reactor 2 suppression chamber, and the evacuation of many personnel from the site, reactor 4 explosion & fuel pool concerns grabbed quite a lot of the attention away from reactor 2. But in fact there have been a number of official reports since the disaster which contain specific estimates of releases which seem to point a huge finger at reactor 2, but this has gone largely unnoticed by the press. Next time I comment I shall discuss these.
Also worth noting that plenty of the above data, and the other stuff that I shall discuss next time, points to a significant release happening over quite a number of hours at various points during the 15th, not just a few minutes where a dry vent may have happened.
And in many respects by this point they were damned if they did and damned if they didn't, as they couldn't manage a wet vent, and a dry vent was preferable to letting the containment fail of its own accord. However as even their desperation dry venting move failed to reduce pressure enough to prolong the life of containment, it almost becomes irrelevant. Bad stuff was going to come out of reactor 2 containment on the 15th one way or another, the pressure it had reached was not sustainable. And in the end as well as the suppression chamber readings falling to zero, drywell pressure had fallen significantly by around 11.35am on the 15th, and there are both readings and estimates of a more sustained release of high levels of contamination over a period of some hours during the daytime of the 15th.
Elbows said
The rise in levels in Tokyo at 4am, a larger rise over the period of 8am and 10am, and further rises between 5pm and 7pm.
Is there a record of the amount of contamination in Tokyo in March? Specifically I 131. I remember trying to find out what the levels were at the time but I could not find anything. Maybe I was looking in the wrong place. As far as I can remember at the time it was said that Tokyo was lucky because due to the wind direction none of the contamination had carried to Tokyo. Also if I remember correctly measurements in Tokyo didn`t begin until around May- June which meant because of the short half life of I 131 it wouldn`t be detected. How forturnate.
@Elbows,
>Also if I remember correctly measurements in Tokyo didn`t begin until around May- June
You don't remember correctly.
Data on radiation doses were updated hourly. You have them here: http://monitoring.tokyo-eiken.go.jp/mp_shinjuku_air_week_list.html
There were daily reports of fallout since March 18 also, you have them here: http://monitoring.tokyo-eiken.go.jp/mon_fallout_data.html
Since they started on March 18, we don't have fallout data for the days between March 15-17, but it didn't rain until March 20-21, so the amount of deposition was probably limited.
About air contamination, there was one daily report like this one since March 15: http://www.sangyo-rodo.metro.tokyo.jp/whats-new/keisoku-0315.pdf
There was a more detailed report about air contamination which included other isotopes like tellurium and strontium, but that was only published in December: http://www.metro.tokyo.jp/INET/CHOUSA/2011/12/60lcq100.htm
They calculated, for example, the amount of each isotope inhaled assuming a breath rate of 22.2 m3/day and based on that they calculated total equivalent dose between March and September based on ICRP coefficients: http://www.metro.tokyo.jp/INET/CHOUSA/2011/12/DATA/60lcq103.pdf
Thanks for pointing out the Tokyo data, however I should just mention that it was not me who asked for that, it was someone else that didn't know data existed for this time period.
Anyway, here is the next set of data I would like to look at in relation to reactor 2.
http://www.meti.go.jp/english/earthquake/nuclear/iaea/pdf/20110911/chapter2.pdf
An earlier comment already drew attention to total release estimates for each reactor, so I won't go into that one again. But there is more stuff to talk about in these reports:
On page II-396, we can see estimated release fractions for the three reactors (which I believe is the percentage of radioactive substances in the reactor that got released to the environment). Note that the estimates for reactors 1 & 3 are in the 0.3% to 0.7% range, but for reactor two the ranges are much broader, 0.4%-7% for Iodine, 0.4%-3% for Tellerium, and 0.3%-6% for Cesium.
On page II-400 pf that document, we can see a chart showing the estimated release rates from the 12th-16th March. Note the large rise shortly before the 15th starts, but that the peak estimated release rate occurs over various periods during the daytime of the 15th.
It was me who asked about the info and thanks very much to the person that posted it. Oh my god! I mean wow! All that info and at the time I couldn't find it anywhere. How stupid of me. I mean, well, in March it must have been on the TV and in the papers, right, and, oh dear, I don`t have a TV nor can read Japanese but if only I had, in all the years I have been here, bothered to learn Japanese I would have known from the headlines in the papers and from the announcements on the TV that I should have stayed indoors on those days.
Not that it matters because from a quick glance at the info about the levels in Tokyo the dose would have been so low that it wouldn't have affected my health anyway. Seeing these figures really sets my mind at ease. I mean, how foolish of me to think that the stinging eyes, sore throat, muscle pain and the fact that I daren't break wind incase I soil my pants ever since the events in March should have anything to do with what happened at that nuclear plant.
A doctor told me a few weeks ago when I asked about the dizzy spells I am having that it is my age. Yes that's it! When I turned 52 this year I suddenly went from a person who hasn't had so much as a sniffle in the previous ten years to a physical wreck who can barely get up in the morning. How stupid and foolish not to realise that it is my age!
I will now return to a document that someone else commented on.
http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_2.pdf
They made reference to a table showing release estimates of different substances from each reactor, which is very useful & relevant info. But there is other stuff of note in this document too.
First it is important to note that these bits of data are based on analysis using nuclear accident modelling, rather than solid data.But they have tried to make the various case scenarios line up with real data that they have measured. They looked at more than one case scenario for each reactor, as shown in the tables on page 3. Focussing on reactor 2, we can discard the TEPCO Case-1 because that was a car that was much too optimistic about amount of fuel damage, whether fuel fell out of reactor vessel, etc. TEPCO Case-2, and government Case 2 and Case 3 are a better fit with the likely reality.
First thing to note is that these cases are based on something else we heard a long time ago, that in order to make their model results match measured data of things like drywell and s/c pressures, they are assuming that some leaks from drywell and/or suppression chamber occurred. In the case of reactor 2, we can see for example that TEPCO's Case-2 involves the following assumptions:
1Amount of water injected through the fire protection line varies with RPV pressure.
2PCV leakage area is ca. 50 cm2.
3S/C leakage area is ca. 300 cm2
Government cases 2 & 3 are similar but looking at drywell and suppression chamber leaks as 2 separate cases (or rather than and)
Page 5 provides further info about these cases by showing estimates for how many hours it took for core damage and reactor vessel damage to occur, and here is where we see that TEPCO case 1 is too optimistic because it assumes no reactor vessel failure.
Anyway now on to the interesting detail:
Someone else already mentioned the table on page 7 which is indeed very important due to the higher estimated magnitude of a range of reactor 2 substances, most obviously Cs-137 but plenty of others too.
Now lets skip ahead to the 2nd graph on page 36, and the graph on page 37. Here we see estimates for where some radioactive substances were located at different points in time, for reactor 2 TEPCO case-2. The thing to note is that there is a level called 'environment' which jumps up. If you check the document for the estimates from reactor 1 & 3, you won't see the environment one jumping up like this, for those reactors things are shown remaining in places such as reactor vessel, drywell and wetwell.
This concludes the bulk of the data I have seen which points a big finger at reactor 2, I hope it has been of interest.
Actually I was accidentally misleading with something I said. Reactor 3 graph does show Environment too, but if you look at the scale of it compared to reactor 2, it doesn't come close.
I also forgot to point out that the reactor 2 graph has other interesting features. Note that as well as stuff being shown in the RPV, D/W, S/C and Environment, locationsR/B and FHB also show up. I am assuming that R/B means reactor building, and FHB means fuel handling building. The fuel handling building one is probably worthy of more attention as it demonstrates a possible pathway for how some of the stuff escaped, especially as the levels in the FHB go down, indicating that the substances only stayed there temporarily before moving on to another location.
Back at home from a short travel.
Very interesting development of the discussion, thanks to all participants!
I find interesting that there is apparently there is no firm confirmation that the rupture disk didn't blow open, as seems from the discussion on the PF ( http://www.physicsforums.com/showthread.php?t=507252&page=3 )
There is also another possibility that I had to think of which could possibly have factored in.
If the small valve opened only partly because of suboptimal makeshift energizing (which cannot be excluded without knowing its design and the circumstances in detail), such could have led to increased sensitivity against clogging.
Furthermore such could have lessened the blowout intensity so that the reactor 2 venting might have been not clearly detectable in a pitch-dark night like the other vents.
Sadly I have to do some work now, will post more thoughts later.
I just noticed that there is a problem with the analysis of the graph as it relates to the timing of a possible drywell vent.
We are looking at a possible vent around midnight, but the first big spike on the graph of radiation levels at the plant actually happens some hours earlier, around 9.30pm on the 14th.
This data is available from a variety of sources but the document I have to hand is the following one, and you can see the graph on page 4:
http://www.jnes.go.jp/content/000119688.pdf
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Shafiqur
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