Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[swl]

I suppose an expert could do a better job than I, otoh since in the context it is more a question of producing a rough order of magnitude estimation.. :-)

If the spent fuel after ten years in the pool is at >100 Sv/h, I'd expect it to be at >1000 Sv/h after one year in the pool, and plausibly at >10000 Sv/h at the time of removal from the core, i.e when the fuel has been fully spent. So, doing simple interpolation I'd find it plausible that half spent fuel could have an activity of >5000 Sv/h, give or take one order of magnitude.

Then does it seems unlikely that any fuel has left containment or sfp in pellet or rod form?

 

[MadderDoc]

Just looking through the report to IAEA for other details that may be an improvement on what we knew before. Is any detail in the following, dealing with reactor 4, more detailed than we knew before, eg more precise location of fires?

http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/chapter_iv-3.pdf from page IV-90

"At around 6:00 on March 15, an explosion assumed to be a hydrogen explosion occurred in the reactor building, and the whole part upward from the one floor below the operation floor as well as the western wall and the wall along the stairs were collapsed.

The extension of the damage caused by the explosion has afaik not been described by Tepco in such detail before, however since it has for a long time been reasonably assumable that the damage caused by the explosion had largely the extension seen in post explosion photos it is not an improvement to what we 'knew' before.

Furthermore, at 9:38, a fire was identified in the northwest part of the fourth floor of the reactor building, but TEPCO confirmed at about 11:00 that it had gone out on its own.

Based on what Tepco has said before, I thought the fire at 09:38 occurred in the _third_ floor, so this is news to me.

A fire was also reported to have broken out in the northwest part of the third floor of the building around 5:45 on March 16, but TEPCO was not able confirm this fire on-site at around 6:15."

I think this also adds to what we knew before. Afaik, previous reports have not included the location
of this fire.

 

[elektrownik]

Other stuff from report that seemed like it might be news to me:

"Spraying onto the PVC" at reactor 3 at 07:39 on the 13th march.

Do we know what this means exactly? I know some people though that later actions by fire crews around 20th-21st march may have been targeting more than just the fuel pools, but we have little info about this possibility. Do we know what form 'Spraying onto the PVC' might have taken on the 13th?

Yes this explain one of video where we can see that they are spraying water from fire truck to center location in unit 3, many peoples were pointing that it is strange.

 

[elektrownik]

http://www.yomiuri.co.jp/dy/national/T110525006455.htm"

 

[SteveElbows]

http://www.yomiuri.co.jp/dy/national/T110525006455.htm"

Old news, discussed here when it first emerged, this was the stuff about 3cm, 7cm and 10cm holes.And as usual I think the government analysis differs somewhat from the TEPCO analysis that this story covers. Stuff I posted about last night in the report to IAEA gives a much more detailed account of when and how radioactive substances got into the environment at various moments, and where venting was not the cause this obviously also involves containment damage.

 

[rowmag]

mailinator.com (throwaway address) worked just fine. Thanks.

I just realized the download link may be on a long-ish timer or even permanent. Here:
http://mailinator.com/displayemail.jsp?email=toho&msgid=139050825

That worked.

By the way here's part two of that article, if you want to do your magic again, with some illustrations of seawall construction:
http://www.doboku-g.com/DownloadPDF.aspx?TocID=6637

 

[MiceAndMen]

Entire 385-page Report of Japanese Govt to IAEA

I combined all 13 chapters into a single PDF. About 11 MB. Contains bookmarks for all chapters and for the individual reactor summaries.

http://min.us/mvoVGLP

 

[tsutsuji]

Here's a part of that image with the English overlay removed. Perhaps someone would be kind enough to translate what it says in Japanese?

SGTS排気管合流部　SGTS exhaust pipes confluence part
４号機　unit 4
３号機 unit 3
排気筒　exhaust stack

 

[zapperzero]

That worked.

By the way here's part two of that article, if you want to do your magic again, with some illustrations of seawall construction:
http://www.doboku-g.com/DownloadPDF.aspx?TocID=6637

With pleasure, it's the least I can do. Here:

http://61.192.182.113/DobokuDownloa...LGPO2MUt9Q2WTiBIj0GfYG/AHbo+dwLZudeiM5z4KXA==

 

[MiceAndMen]

SGTS排気管合流部　SGTS exhaust pipes confluence part
４号機　unit 4
３号機 unit 3
排気筒　exhaust stack

Thanks, tsutsuji.

Thank you, too, rowmag and zapperzero for those article links.

 

[MadderDoc]

Other stuff from report that seemed like it might be news to me:

"Spraying onto the PVC" at reactor 3 at 07:39 on the 13th march.

Do we know what this means exactly? I know some people though that later actions by fire crews around 20th-21st march may have been targeting more than just the fuel pools, but we have little info about this possibility. Do we know what form 'Spraying onto the PVC' might have taken on the 13th?<..>

I don't think so, it makes no sense, I suspect there could be language trouble. All three Tepco
press releases from March 13th from as early as 9am say that "spraying in order to lower pressure level
within the reactor containment vessel has been cancelled', here's the context:

"High Pressure Core Injection System has been automatically shut down and water injection
to the reactor is currently interrupted. We are examining alternative way to inject water.
Also, following the instruction by the government and with fully securing safety, steps to
lowering the pressure of reactor containment vessel has been taken. Spraying in order
to lower pressure level within the reactor containment vessel has been cancelled."

 

[zapperzero]

Another link from the excellent ex-skf blog.

Circumstantial evidence that Fukushima Dai-ichi containment broke after the earthquake but before the tsunami:

http://www.yomiuri.co.jp/science/news/20110608-OYT1T00583.htm?from=top

http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fwww.yomiuri.co.jp%2Fscience%2Fnews%2F20110608-OYT1T00583.htm%3Ffrom%3Dtop

Apparently there's Cesium in the water found in the basements at Fukushima Dai-ni. TEPCO says that water came in when the tsunami happened.

 

[biffvernon]

So now we know that the power station is built on solid geology not alluvium. 'Mudstone' should be read as stone rather than mud. The buildings are not going to slide into the sea, as someone suggested a great many posts ago.

The significant detail about how permeable the rock immediately below the reactors buildings is to the movement of groundwater and potentially radioactive cooling water still eludes us.

 

[SteveElbows]

Another link from the excellent ex-skf blog.

Circumstantial evidence that Fukushima Dai-ichi containment broke after the earthquake but before the tsunami:

Im really not at all convinced that the article is claiming that the Dai-ichi contamination reached Dai-ni via the sea, let alone that this happened before the tsunami.

Does it not seem far, far more likely that it reached the other plant via the air, and accumulated in water there due to the rain?

 

[tsutsuji]

This article in the Los Angeles Times says the report to the IAEA is 750 pages long. So either the LA Times story is wrong or there's a lot more to it than what's posted on the Japanese government's website.

http://www.latimes.com/news/nationworld/world/la-fg-japan-nuclear-report-20110608,0,7481490.story

Here are the number of pages of the Japanese language pdfs available at http://www.kantei.go.jp/jp/topics/2011/iaea_houkokusho.html :

001 pages 00-0-hyoushi.pdf
002 pages 00-1-mokuji.pdf
040 pages 00-2-gaiyo.pdf
002 pages 01-hajimeni.pdf
010 pages 02-shikumi.pdf
060 pages 03-jishin-tsunami.pdf
120 pages 04-accident.pdf
036 pages 05-kinkyu.pdf
006 pages 06-kankyo.pdf
012 pages 07-dose.pdf
004 pages 08-kokusai.pdf
012 pages 09-communication.pdf
010 pages 10-torikumi.pdf
004 pages 11-sonota.pdf
012 pages 12-kyokun.pdf
002 pages 13-musubi.pdf
005 pages app-chap02.pdf
064 pages app-chap04-1.pdf
053 pages app-chap04-2.pdf
022 pages app-chap04-3.pdf
113 pages app-chap05.pdf
025 pages app-chap06.pdf
005 pages app-chap07.pdf
001 pages app-chap08.pdf
018 pages app-chap09.pdf
066 pages app-chap10.pdf
009 pages app-chap11.pdf

So I find a total of 714 pages (and 66.8 MB file size)

 

[SteveElbows]

Im really not at all convinced that the article is claiming that the Dai-ichi contamination reached Dai-ni via the sea, let alone that this happened before the tsunami.

Does it not seem far, far more likely that it reached the other plant via the air, and accumulated in water there due to the rain?

Furthermore I expect that Ex-SKF are interested in this story because of the possibility that the radiation comes from damage at Dai-ni itself, certainly I would not be at all surprised to learn that there had been a bit more damage at that plant than we are generally lead to believe. The report to IAEA mentions this other plant and some of the detail troubles me.

 

[zapperzero]

Here are the number of pages of the Japanese language pdfs available at http://www.kantei.go.jp/jp/topics/2011/iaea_houkokusho.html :
So I find a total of 705 pages (and 66.8 MB file size)

As usual, the appendices seem especially interesting. Those to chapters 4 and 5 contain charts of pressures & temps (some of it is stuff we saw in raw form in TEPCO's report, on the photographed strips of paper), plant schematics, detailed fallout maps with exact positions of the monitoring posts. Some have English labels.

These appendices are absent from the English version (for now, at least).

Starts to look more like what I'd expect from a professionally-run organization (albeit one using circa 1970 vintage technology).

No energy spectra though, not that I can find. Just the usual cesium and iodine measurements.

 

[Danuta]

Fukushima nuclear disaster surprisingly getting some recent MSM coverage. Arnie G. speaks on CNN. June 7th.

Only half the vid...

http://edition.cnn.com/video/#/video/politics/2011/06/07/jk.radiation.gundersen.cnn"

 

[tsutsuji]

The geologist would bring the information, and point to sources of information, both raw and compiled.

Information on the geology and underground water exists for that location.

I am convinced of that.

On page 11 of the roadmap at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110517e5.pdf they said that they were planning to perform a seepage analysis as part of their examination of groundwater shielding methods.

 

[tonio]

Which once again points out how unfortunate it is that we are lacking a poster knowledgeable of the subject of geology.

It simply can't be true that the underground rock formations, water tables and streams at the Fukushima site are an unknown.

Somebody did the engineering for that dam.

Well, I happen to be a geologist, specialized in soil and groundwater contamination. I am sure that the geology and geohydrology of the site are known, in order to be able to design the foundations of the plant and in order to design the groundwater withdrawal system, necessary to keep the basements of the plant dry (I understood that such a system exists).

I have added a simple sketch of what seems to me the most likely situation of the Fukushima plant. I assume the following, based on what I see at Google Earth:
- the plant has been built on a platform, partly excavated into the slope and partly situated on a layer of rubble, bulldozed into the sea.
- the general direction of ground water flow is perpendicular towards the sea;
- at the foot of the slope there is probably some kind of drainage ditch which collects both surface runoff and ground water coming from higher grounds;
- the whole platform is probably paved with concrete of asphalt and provided with a rainwater drainage system;
- the rain water and ground water collected in the drainage ditch and the drainage system is led into the sea.

Based on the above:
- contaminated surface runoff will probably be directly discharged into the sea unless this water is intercepted and collected somewhere (which is not the case afaik);
- contaminated surface runoff may leak into the ground in case of damaged pavements and/or drainage pipes;
- contaminated water in the reactor buildings may leak into the ground in case of damaged walls/floors/underground pipes, etc.

The time it takes for the contaminated ground water to reach the sea depends on the permeability of the ground (which may consist of bedrock, rubble and possible also weathered bedrock (soil)), on the slope of the groundwater table towards the sea and on the chemical behavior of the radioactive substances.

Hope this helps.

 

[zapperzero]

Im really not at all convinced that the article is claiming that the Dai-ichi contamination reached Dai-ni via the sea, let alone that this happened before the tsunami.

Does it not seem far, far more likely that it reached the other plant via the air, and accumulated in water there due to the rain?

I did not claim it reached Dai-ni via water, nor does the article. That would be impossible, in the time given (an hour elapsed between quake and tsunami).

EDIT: I just saw your later post. Indeed, there are two possibilities:
1. unreported containment breach at Dai-ni
2. airborne transport from an as yet unreported pre-tsunami breach at Dai-ichi

 

[joewein]

Interesting why they are installing this not in center of SFP, sfp is weakest there ?, the point where they are installing it is strongest I think (because of drywell thick): http://www.tepco.co.jp/en/news/110311/images/110607_1f_2.pdf

The spot marked in green on the bottom left diagram is where the steel support pillars will be - under the middle of the pool.

Looks like they'll also build a concrete wall at the red spot next to the dry well wall.

 

[Bioengineer01]

Well now we can read about it in the english documents linked to today, at least if I have found the right bit and am putting 2 & 2 together properly, as part of their analysis they mention that steam may have been escaping from the HPCI.

Sorry if I can't be more precise, but I have a fuzzy memory about of a perimeter radiation sensor that went off early on in the event

 

[Bioengineer01]

It's funny, I was just looking at old news reports from the March 14-17th period, noting the vast amounts of deception and blatant lies fed to the world. I've often thought that you would have to be disconnected from reality to look at the video of the explosions, and then believe the nonsense the media was feeding 24/7

The actions of the US at the time, where they moved their entire rescue operation to the other side of Japan, avoiding the ocean down wind from the fires and explosions, told the real tale of the radiation escaping out to sea.

Of course nobody did any measurements at all of what was blowing down wind over the ocean, so it's about impossible to tell what the real amounts are.

I have also been struggling to understand at a macro level the order of magnitude of the release into the Pacific Ocean and can't find enough data to even guesstimate it. Very frustrating. My opinion and that of my colleagues is that the largest release has been and still is happening to the Ocean. Also, we all suspect that there is a continuous flow of isotopes to the ground water and from the ground water to the Ocean. The tell me that in most cases ground water in coastal sites flows to the Ocean. None of us has any information of deep water wells in the region and how they are interconnected, although we are certain that the information is out there.

 

[etudiant]

The amount of water in question is 3000 tons, in the DaiNi basement. Airborne contamination is pretty unlikely. Moreover, the tsunami flooding was with clean sea water.
So the contamination was locally sourced.
Is not cesium an indicator that some fuel elements have leaked?
Afaik, DaiNi was rated as INES 3 after the tsunami, saved by one outside power line, but no lasting damage was reported then.

 

[rowmag]

So now we know that the power station is built on solid geology not alluvium. 'Mudstone' should be read as stone rather than mud. The buildings are not going to slide into the sea, as someone suggested a great many posts ago.

The significant detail about how permeable the rock immediately below the reactors buildings is to the movement of groundwater and potentially radioactive cooling water still eludes us.

Do the N values provide any indirect hints? I don't know how to interpret how they are displayed in the figure, but in the text it mentions that the lower layers typically have N=40 or greater. (I know N is a soil hardness measure, not a permeability one, but could naively imagine that a high N value suggests low permeability, absent cracks.)

 

[Bioengineer01]

RPV
All the media talk about % fuel melt is meaningless. The questions that should be asked are: where did the fuel go? and, what can be done about it?

Completely agree, the question I have is, whether anybody in the forum knows if it is true that this is something that TEPCO could be measuring to understand if the Corium is in the ground. And I know that we can't know if they are doing it or not, I am just curious if you think that this is something that could be done if they wanted to: "There are sensitive sensors all around the grounds listening for underground activity, as well as satellite based imagery used to locate bunkers and tunnels that can image the ground density. 1300C material generates pressure underground that alters the density of the ground, and these changes can be detected and visualized"

 

[elektrownik]

Here are some interesting plots, some of them show hight temperature >2500C, from where they take those data ? http://www.kantei.go.jp/jp/topics/2011/pdf/app-chap04-1.pdf

 

[etudiant]

I have also been struggling to understand at a macro level the order of magnitude of the release into the Pacific Ocean and can't find enough data to even guesstimate it. Very frustrating. My opinion and that of my colleagues is that the largest release has been and still is happening to the Ocean. Also, we all suspect that there is a continuous flow of isotopes to the ground water and from the ground water to the Ocean. The tell me that in most cases ground water in coastal sites flows to the Ocean. None of us has any information of deep water wells in the region and how they are interconnected, although we are certain that the information is out there.

The initial airborne release estimates from ZAMG in Austria, based on CTBT monitoring data, was about 10% of the total Chernobyl output of cesium and iodine per hour. Given that we now know the cores were seriously damaged quite early, those estimates seem at least as reasonable as the later downward revisions, which were never formally documented afaik.
We can hope that the bulk of the waterborne contamination is still within the site, simply because the level of Lake Fukushima is showing no signs of decline. Information as to the actual level of activity of that water is scarce, apart from the few samples taken during the efforts to halt ocean leakage. It might be useful to take those measures. extrapolate to the current volume and compare to the total in the reactors before the accident.

 

[jlduh]

The amount of water in question is 3000 tons, in the DaiNi basement. Airborne contamination is pretty unlikely. Moreover, the tsunami flooding was with clean sea water.
So the contamination was locally sourced.
Is not cesium an indicator that some fuel elements have leaked?
Afaik, DaiNi was rated as INES 3 after the tsunami, saved by one outside power line, but no lasting damage was reported then.

Article from NHK on Daini contaminated water:

http://www3.nhk.or.jp/daily/english/08_30.html

The Tokyo Electric Power Company is studying a plan to decontaminate seawater pooled at the Fukushima Daini nuclear power plant and discharge it into the sea.

TEPCO says about 3,000 cubic meters of radioactive seawater has been stagnant in the basement of the plant's reactor and turbine buildings since being hit by a tsunami following the March 11th earthquake.

The utility says the concentration of radioactive cesium in the water is 30 times the permissible limit, but that it contains no other radioactive materials exceeding the safety limits.

I remember every member on this forum that (we discussed about this a long time ago but I'm not sure everybody noted it) Tepco released the information on its website that they were "preparing to vent" at N°1 DAINI reactor after "increase of pressure in the reactor containment possibly due to coolant leakage" (that was March 12):

http://www.tepco.co.jp/en/press/corp-com/release/11031104-e.html


http://www.tepco.co.jp/en/press/corp-com/release/11031218-e.html

At 6:08PM, we announced the increase in reactor containment vessel
pressure, assumed to be due to leakage of reactor coolant. However, we do
not believe there is leakage of reactor coolant in the containment vessel
at this moment.
- At 5:22AM, the temperature of the suppression chamber exceeded 100
degrees. As the reactor pressure suppression function was lost, at 5:22AM,
it was determined that a specific incident stipulated in article 15,
clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
the reactor containment vessel (partial discharge of air containing
radioactive materials) in order to fully secure safety. This preparation
work started at around 9:43am.

They didn't do it, but this probably shows that something happened there. These 3000 tons of water with Cs at a level 30 times the allowed limit could be an other signal of this, to be confirmed...

 

[Astronuc]

Here are some interesting plots, some of them show hight temperature >2500C, from where they take those data ? http://www.kantei.go.jp/jp/topics/2011/pdf/app-chap04-1.pdf

Ostensibly, those are the results of calculations made with the MAAP code. The maximum temperature is about 2800C, the melting point of UO₂.

From the English version

In addition, in order to supplement this limited information, TEPCO carried out analysis and evaluation of reactor situation of Unit 1,Unit 2 and Unit 3 using MAAP, which is a Severe Accident Analysis Code, based on gained operating records and parameters. The results were reported to NISA on May 23. NISA carried out a crosscheck by using other severe Accident Analysis Code, MELCOR in order to cross-check for validation of TEPCO’s analysis with the assistance of Incorporated Administrative Agency Japan Nuclear Energy Safety Organization in order to confirm the adequacy of the analysis and evaluation concerned by using MELCOR, another severe accident analysis code. The report of analysis and evaluation conducted by Tokyo Electric Power Company is shown in Appended Reference IV-1, and analytic results by crosscheck are shown in Appended Reference IV-2.

 

[rowmag]

Another link from the excellent ex-skf blog.

Circumstantial evidence that Fukushima Dai-ichi containment broke after the earthquake but before the tsunami:

http://www.yomiuri.co.jp/science/news/20110608-OYT1T00583.htm?from=top

http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fwww.yomiuri.co.jp%2Fscience%2Fnews%2F20110608-OYT1T00583.htm%3Ffrom%3Dtop

Apparently there's Cesium in the water found in the basements at Fukushima Dai-ni. TEPCO says that water came in when the tsunami happened.

So they are saying there is cobalt-60 in the water, apparently from rusted piping (at Daini itself, seems to be implied). Plus there is cesium-137 and -134 that they think might have flown in from Daiichi some time in the past 3 months.

Have they reported any previous measurements made on this water?

 

[SteveElbows]

I did not claim it reached Dai-ni via water, nor does the article. That would be impossible, in the time given (an hour elapsed between quake and tsunami).

I got confused because you said 'Circumstantial evidence that Fukushima Dai-ichi containment broke after the earthquake but before the tsunami' so I thought you were implying that the stuff must have gotten into sea before tsunami. Did you actually mean that the stuff could of traveled by air before the tsunami, and was then carried inside the building by the tsunami?

 

[zapperzero]

So they are saying there is cobalt-60 in the water, apparently from rusted piping (at Daini itself, seems to be implied). Plus there is cesium-137 and -134 that they think might have flown in from Daiichi some time in the past 3 months.

Have they reported any previous measurements made on this water?

No. They have not. Also, "sometime in the past months" is highly disingenuous. That water is in a god damn basement. No way it could have gotten contaminated after it got into the basement, unless Dai-ni was/is in much, much deeper trouble than we were ever told.

 

[zapperzero]

I got confused because you said 'Circumstantial evidence that Fukushima Dai-ichi containment broke after the earthquake but before the tsunami' so I thought you were implying that the stuff must have gotten into sea before tsunami. Did you actually mean that the stuff could of traveled by air before the tsunami, and was then carried inside the building by the tsunami?

Yes that's what I am saying. I am saying it MUST have happened like that, because those basements are not open to the outside air normally. It's only ten kilometers or so as the crow flies. A gentle breeze would have had more than enough time.

 

[elektrownik]

And is this interesting: http://www.tepco.co.jp/en/news/110311/images/110608_06_2.pdf ?

 

[zapperzero]

And is this interesting: http://www.tepco.co.jp/en/news/110311/images/110608_06_2.pdf ?

Only if they exhausted stuff. I don't think they do, in normal operation. Do they?

 

[elektrownik]

Only if they exhausted stuff. I don't think they do, in normal operation. Do they?

Here is more:

At 4:00 pm on June 7, air leak was found at the weld zone of unit 4's main
emission duct by TEPCO employee. (10cm×3cm 2 places ). Radioactive
materials in the air were below measurable limits.
We will implement the repair work and check similar points soon. No outlier
at main emission monitor and monitoring post was detected. No radiation
effect is found outside.

 

[NUCENG]

Only if they exhausted stuff. I don't think they do, in normal operation. Do they?

BWRs boil water in the reactor. Small amounts of "tramp" uranium on fuel assemblies add fission products to steam and corrosion and activation products are also present. Gaseous wastes are removed from the condensers by air ejectors. The air ejector output stream is pocessed in the offgas system building to allow time for the short lived products to decay. Then the remainder is exhausted through the common offgas stack for an elevated release to maximize dispersion. At Fukushima Daiichi the offgas stack is common to plants 1-4 and is south of unit 4.

 

[zapperzero]

BWRs boil water in the reactor. Small amounts of "tramp" uranium on fuel assemblies add fission products to steam and corrosion and activation products are also present. Gaseous wastes are removed from the condensers by air ejectors. The air ejector output stream is pocessed in the offgas system building to allow time for the short lived products to decay. Then the remainder is exhausted through the common offgas stack for an elevated release to maximize dispersion. At Fukushima the offgas stack is common to plants 1-4 and is south of unit 4.

Thanks a lot for the explanation.

 

[etudiant]

BWRs boil water in the reactor. Small amounts of "tramp" uranium on fuel assemblies add fission products to steam and corrosion and activation products are also present. Gaseous wastes are removed from the condensers by air ejectors. The air ejector output stream is pocessed in the offgas system building to allow time for the short lived products to decay. Then the remainder is exhausted through the common offgas stack for an elevated release to maximize dispersion. At Fukushima Daiichi the offgas stack is common to plants 1-4 and is south of unit 4.

Thank you for the explanation.
Would these emissions be a plausible explanation for the cesium contamination in the sea water pooled in the basement?
I'm having a difficult time quantifying the scale of that problem, as contamination 30x the standard for release no longer sounds very threatening. Is this in line with some fuel rod breach or some steam leak from the turbines or what?

 

[Bioengineer01]

Excellent, finally a document that sheds some significant light on timing of certain things.

This part of the report to IAEA deals with radioactive release into the environment:

After earthquake, the discharge of radioactive materials became evident early on the morning of March 12 when the air dose rate measured by a monitoring car near MP-6(monitoring post No. 6 in the site of Fukushima Dai-ichi NPS) increased. It can be estimated that there was a leakage of radioactive materials from the PCV and a discharge of such materials to the air, as a slight decrease in the PCV pressure was observed in Unit 1 after an abnormal rise at this point. According to an analytical result, that fuel meltdown had already started.

Dont get me wrong, its not perfect, it doesn't cover everything in great detail but its way better than the complete lack of narrative we've previously had on this subject from official sources. Dont think there's anything for those fascinated by reactor 3 march 20th-23rd events though.

Yes Thanks! And, Yap! this is the perimeter sensor that I remembered reading about and mentioned before

 

[robinson]

If that is not a theoretical question but an assumption that this could have happened, I believe that the logs from reactor 1 SCRAM seem to show that the rods insertion was successful.

It was hypothetical. I was wondering what sort of disaster would occur if about everything went wrong, and how long it would take.

 

[zapperzero]

Thank you for the explanation.
Would these emissions be a plausible explanation for the cesium contamination in the sea water pooled in the basement?
I'm having a difficult time quantifying the scale of that problem, as contamination 30x the standard for release no longer sounds very threatening. Is this in line with some fuel rod breach or some steam leak from the turbines or what?

Water from the coolant circuit should NOT be in the basement, regardless. It circulates between the reactor, the turbine and the condenser. No breach of the coolant loop has been reported for Fukushima Dai-ni.

 

[MadderDoc]

Intriguingly the Report of the Japanese Government
to the IAEA gives off this new bit of information regarding the explosion at unit 3:

"Along with the explosion, the oil for the MG sets for the control of the rotating speed of
recirculation pumps burnt concurrently at the heavily damaged west side of the 4th floor
of reactor building."

I am left wondering how it could possibly have been determined, that a fire was ongoing -- concurrent with the explosion -- in the oil of the recirculation flow control system M/G sets.

 

[jim hardy]

"""It was hypothetical. I was wondering what sort of disaster would occur if about everything went wrong, and how long it would take.""""

failure to "scram"? That was an industry issue in mid 1970's and much analysis was done to answer "What If". I remember the time well. They called it 'Anticipated Transient Without Scram' .

Try google search on ATWS BWR and look for .gov reports from about 1975 to 1981 time frame.

 

[SteveElbows]

Yes that's what I am saying. I am saying it MUST have happened like that, because those basements are not open to the outside air normally. It's only ten kilometers or so as the crow flies. A gentle breeze would have had more than enough time.

Well I don't rule out the other possibility that it traveled by air and then got into the basement via rain & groundwater problems later on.

But to be perfectly honest if I had to bet money on one option right now, I would be very tempted to go with 'slightly damage to at least one Daini reactor'. Things were quite bad there for a number of days even though they were not totally without power. I wait to learn more about the stuff mentioned at the end of one of the report to IAEA documents, which features some Drywell spraying, pressure issues, and some control rod drift alarms.

Or, if there was no such damage and the stuff really came from Daiichi, I really do struggle to believe that it arrived before the tsunami. I know we now have a variety of tales and data to do with stuff escaping much earlier than originally thought, but not that early, a release within the first hour that would show up km away really does not fit very well with the data.

 

[NUCENG]

I don't think so, it makes no sense, I suspect there could be language trouble. All three Tepco
press releases from March 13th from as early as 9am say that "spraying in order to lower pressure level
within the reactor containment vessel has been cancelled', here's the context:

"High Pressure Core Injection System has been automatically shut down and water injection
to the reactor is currently interrupted. We are examining alternative way to inject water.
Also, following the instruction by the government and with fully securing safety, steps to
lowering the pressure of reactor containment vessel has been taken. Spraying in order
to lower pressure level within the reactor containment vessel has been cancelled."

They were spraying containment to condense any steam there and reduce containment pressure. With no power available they were probably using the fire fighting system to do this.

 

[SteveElbows]

I am left wondering how it could possibly have been determined, that a fire was ongoing -- concurrent with the explosion -- in the oil of the recirculation flow control system M/G sets.

If they eyeballed a fire at that location once the initial dust from the explosion died down, they may reach that conclusion.

 

[robinson]

While it was mostly lost at the time, Daini did report a fire and some scary moments after the tsunami and quake.