Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[jim hardy]

thanks 7.3m - 5.18m = 6.95 ft for a lifting bar and crane hook...

tight, sure not much clearance to lift it above floor... but it might work.

Murphy wouldn't let us have a definite go-no go.

thanks!

 

[yakiniku]

As long as there isn't a problem with re-criticalities the worst is probably over with unit one. They will probablyhave to keep cooling it for the next decade or so.

Are there indications that if the fuel has melted and is at the bottom of the RPV that it is being sufficiently cooled such that it won't melt through the RPV?

 

[MiceAndMen]

They now believe 100 percent fuel melt in reactor one, with some water cooling still occurring in the bottom of the vessel, as indicated by the relatively low temperatures measured outside the vessel.

The word "meltdown" is very non-specific in its meaning, I know that. But this sounds like confirmation of one. If all the fuel has relocated into the bottom of the RPV and cooling is uncertain, then do they have any choice now except to wait and see what happens next?

Even if the drywell could hold water, I don't think you'd want any there just waiting for corium to fall into it. That could create the mother of all steam explosions and perhaps a huge release of fission products into the environment.

 

[razzz]

I was under the impression that if you commit to a GE designed reactor, you get an onsite nuclear engineer from GE to assist and advise for life. 6 reactors, 6 onsite nuclear engineers from GE. Not that GE gets to approve of anything but they certainly are in the know about how their designs are performing from day 1.

Unit 1 sounds scary because they don't know what's going on inside. Wondering if the saltwater injections changed the parameters of cooling somehow via rapid decay or encrustation or some other hereto unknown reaction(s). That radioactive lava has to be a couple of feet thick or more.

 

[Jim Lagerfeld]

There is no "core" anymore. That's an anachronism in the case of units 1,2 and 3.

There is a puddle of corium (or several such globs or puddles) which have been cooling for 2 months and which will decline in temperature as time goes on.

You are dead right on this, it's no longer a 'core' as such. And it will cool eventually, and 10 years of water cooling now sounds more realistic than TEPCO's 'cold shutdown in 6-9 months' statement.

Tepco were very keen to stress that there is still 'some' water over the corium blob(s) and that this 'is currently cooling the fuel'.

However to me, it also seems that their ability to get sufficient water to the blob is deteriorating rather than improving over time. They also announced that there is no measurable water in the secondary containment, so they will have to abandon the cool from the outside 'water coffin' plan too.

Hopefully they are able to work around the 700mSv/h inside the building and get a more effective cooling system up and running, but if they can't, how long for the blob to cool of it's own accord?

 

[AntonL]

I wish I could concur with you on that point, but the fact that they are unable to maintain any stable water level over the core at this point does not inspire confidence.

http://www.47news.jp/CN/201105/CN2011051201000254.html

This summary goes on to say that they are 'making preparations' towards the installation of a new cooling system for reactor one, but that they are currently struggling to 'come to grips' with conditions inside the reactor one building and that this would 'probably have an impact' on the implementation of the plan.

And this is all presuming that nothing goes wrong at any of the other potential crisis points.

The new cooling system may have to be rethought. "Feed and Bleed" is working at the moment, once the reactor vessel is flooded the cooling dynamics are different which could lead to unexpected results.

I will be watching Tepco's reaction with interest

 

[Jim Lagerfeld]

Final note - in case today's briefing seemed unusually forthright and unambiguous, NHK online is currently 'news flash' ing the following:

"Tokyo Electric Power Company says water may be leaking from a hole in the No.1 reactor at the Fukushima Daiichi nuclear plant, causing a sharp drop in the water level inside the reactor."

http://www3.nhk.or.jp/nhkworld/index.html

Different interpretation of the same data? Doesn't seem to match the initial statement that faulty gauges had led them to misjudge the water level from the start.

 

[NUCENG]

I was under the impression that if you commit to a GE designed reactor, you get an onsite nuclear engineer from GE to assist and advise for life. 6 reactors, 6 onsite nuclear engineers from GE. Not that GE gets to approve of anything but they certainly are in the know about how their designs are performing from day 1.

Unit 1 sounds scary because they don't know what's going on inside. Wondering if the saltwater injections changed the parameters of cooling somehow via rapid decay or encrustation or some other hereto unknown reaction(s). That radioactive lava has to be a couple of feet thick or more.

When I first started work at a BWR the plant had a resident GE project manager. Since that time a number of other contactors have gone into competition with GE. GE has pulled back most if not all of the site residents. One of the problems for plants of the vintage of Fukushima is that the engineers at GE who designed the plants have retired. They have lots od drawings, analysis, and calculations that were generated in the 60s and 70s before digital records were feasible. Finding those documents requires a manual search. They have been working on digital records, but most of that effort is capturing current work and designs for the new generation plants. The engineers that I worked with were competent and did the best they could but in general, GE won't take on efforts to reconstitute design Bases. Many US plants spent a lot of money searching and capturing original plant correspondence and records and issued design basis documennts for major systems. GE still performs refueling safety analysis for most BWRs but they have competitors for that now as well.

 

[a|F]

You are dead right on this, it's no longer a 'core' as such. However to me, it also seems that their ability to get sufficient water to the blob is deteriorating rather than improving over time. They also announced that there is no measurable water in the secondary containment, so they will have to abandon the cool from the outside 'water coffin' plan too.

It seems to have been a blob for quite some time now... Wouldn't you want to keep water in the drywell to help cool the RPV, which would in turn help to keep the corium blob cooled? I believe that could prevent melt-through, but have no resources to back up such a claim.

No measurable water in secondary containment is a good thing- that's the reactor building! Haven't read your source, therefore not sure if you're confused or they are. The "water coffin" would require filling the primary containment (drywell), which I was under the impression had already occured...

 

[a|F]

When tanks are bottom filled, what safety mechanisms are available to stop the liquids flowing back out if there is a failure in the filling system?

A check valve.

 

[AntonL]

Final note - in case today's briefing seemed unusually forthright and unambiguous, NHK online is currently 'news flash' ing the following:

"Tokyo Electric Power Company says water may be leaking from a hole in the No.1 reactor at the Fukushima Daiichi nuclear plant, causing a sharp drop in the water level inside the reactor."

http://www3.nhk.or.jp/nhkworld/index.html

Different interpretation of the same data? Doesn't seem to match the initial statement that faulty gauges had led them to misjudge the water level from the start.

With all the reporting mistakes Tepco made in the past and corrections for which they were officially reprimanded, I am sure that the water level findings were double and treble checked before releasing to the public and involving the Chief Cabinet Secretary Yukio Edano. Tepco cannot afford to come tomorrow and apologise once again that a mistake has been made with such a serious issue.

Now clarity has to be given on the pressure readings of the reactor vessel, how can one have a leak and record pressures of 0.4 and 1.3MPa_abs (A and B channels)

 

[jim hardy]

Nuceng you are a BWR guy?
do you have knowledge of the pressure sensors used for reactor and drywell?

Like where they're located, sense points, are they subjected to drywell temperature and radiation? If outside containment how are they isolated - sealed diaphragms with fill fluid? Are the sensors old fashioned electromechancal contraptions?

Reason i ask is am trying to understand why #3 reactor and drywell pressures tracked injection flow after the explosion, around Mar 20th, and why 3 has showed vacuum lately.

just curious if maybe you were an I&C type and familiar with instruments. don't go to any trouble.
And if this is redundant please excuse. I watched this board for several weeks but was active on another, didnt read every post here but think i am reasonably current.

 

[Jim Lagerfeld]

It seems to have been a blob for quite some time now... Wouldn't you want to keep water in the drywell to help cool the RPV, which would in turn help to keep the corium blob cooled? I believe that could prevent melt-through, but have no resources to back up such a claim.

No measurable water in secondary containment is a good thing- that's the reactor building! Haven't read your source; therefore not sure if you're confused or they are. The "water coffin" would require filling the primary containment (drywell), which I was under the impression had already occured...

Sorry that mistake is 100% mine, thanks for picking it up. I was looking at two stories :

http://www.47news.jp/CN/201105/CN2011051201000254.html
http://www.mbs.jp/news/jnn_4723222_zen.shtml

mbs suggests "圧力容器やその外側の格納容器にほとんど水が溜まっていないこと [...] 「格納容器に水をためる」という、当初、予定していた冷却方法の大幅な見直しを迫られることになります。

- Almost no water measurable in both the reactor pressure vessel and the reactor containment vessel (as you point out - "primary containment"), therefore the 'water entombment' scheme will need to be drastically revised.

47 news suggests "東電は、１号機の原子炉格納容器を水で満たし、燃料の入った圧力容器ごと冷やす「冠水」に向けた作業を続けているが、格納容器の水位も不明という。"

- Plans to flood the reactor containment vessel ("primary containment") with water to cool the the fuel contained within the reactor pressure vessel will continue, however the the water level in the primary containment is also suspect / unclear.

I'll stop now, as I'm sure someone will be along with a better translation of the actual press conference soon and I'm getting out of my depth.

 

[Rive]

With all the reporting mistakes Tepco made in the past and corrections for which they were officially reprimanded, I am sure that the water level findings were double and treble checked before releasing to the public and involving the Chief Cabinet Secretary Yukio Edano. Tepco cannot afford to come tomorrow and apologise once again that a mistake has been made with such a serious issue.

IMO it can be even just the announcement of missing/false data. The available translations are not clear enough if there is no water or they can't measure it.

 

[clancy688]

They now believe 100 percent fuel melt in reactor one, with some water cooling still occurring in the bottom of the vessel, as indicated by the relatively low temperatures measured outside the vessel.

Where do they say that? I can't find that part about "100 percent fuel melt" in the provided links.

Moreover, it's a mystery for me. In several aspects. Former assessments of Mark 1 Containment security (provided by NUCENG) reported that an uncovered core would breach the reactor vessel in less than one hour.
Now we learn that Unit was likely uncovered for two months. Yet there were no indications of any breaches.
Furthermore, as EX-SKF pointed out in his blog, where the hell did the water go? They pumped thousands of tons of water inside the RPV and now there's hardly any left. Highly contaminated basements were reported for Units 2 and 3 afaik, but NOT for Unit 1.
And I was just thinking that at least with Unit 1 we were sure what's going on...

So I'd like to ask one question:

- Why DIDN'T the RPV and containment fail big way (Corium relocation through the basement and in the earth) when the core was uncovered for months? Is the Mark I containment in the end not as bad as everyone says?

 

[|Fred]

Here is the link http://www.ustream.tv/recorded/14641270 I welcome translation insight
if it has been said it was there, I expect more today

 

[MiceAndMen]

Bloomberg News has picked up the story now, too.

http://www.bloomberg.com/news/2011-05-12/japan-suffers-setback-at-fukushima-after-no-1-reactor-s-fuel-rods-exposed.html

 

[Jim Lagerfeld]

Where do they say that? I can't find that part about "100 percent fuel melt" in the provided links.

"Nuclear fuel rods inside the No. 1 reactor of the crippled Fukushima Daiichi power plant likely melted after being fully exposed and are being cooled in water at the bottom of the pressure vessel"

- http://english.kyodonews.jp/news/2011/05/90559.html

It captures the tone of the original japanese quite well.

and the other story I paraphrased in my previous posts:

"１号機で、原子炉圧力容器内の冷却水の水位が想定よりも低く、長さ約４メートルの燃料が完全に露出して、溶け落ちたとみられると発表した"

http://www.47news.jp/CN/201105/CN2011051201000254.html

"(it has been announced that) at reactor 1, the level of cooling water inside the reactor pressure vessel is lower than previously supposed, and furthermore the fuel rods have been exposed along their entire 4 meter length, and have melted and slumped ("溶け落ちた").

So you are correct - perhaps we could rather say that they suspect "100 percent fuel exposure and melting", as the actual state of the fuel seems impossible to confirm at this point.

 

[razzz]

When I first started work at a BWR the plant had a resident GE project manager. Since that time a number of other contactors have gone into competition with GE. GE has pulled back most if not all of the site residents. One of the problems for plants of the vintage of Fukushima is that the engineers at GE who designed the plants have retired. They have lots od drawings, analysis, and calculations that were generated in the 60s and 70s before digital records were feasible. Finding those documents requires a manual search. They have been working on digital records, but most of that effort is capturing current work and designs for the new generation plants. The engineers that I worked with were competent and did the best they could but in general, GE won't take on efforts to reconstitute design Bases. Many US plants spent a lot of money searching and capturing original plant correspondence and records and issued design basis documennts for major systems. GE still performs refueling safety analysis for most BWRs but they have competitors for that now as well.

Thanks for that Nuceng. I take it when the nuke accident first occurred and Japan reached out to the US for aid, it was the military and GE that was recommending to expand the no-go zone and shut all GE reactors down (on the island) to inspect the known weak points, anybody else were just sock puppets.

 

[yakiniku]

IMO it can be even just the announcement of missing/false data. The available translations are not clear enough if there is no water or they can't measure it.

The original news in Japanese on MBS only says "hardly any water" (http://www.mbs.jp/news/jnn_4723222_zen.shtml ) :

福島第一原発の１号機で、圧力容器やその外側の格納容器にほとんど水が溜まっていないことが、ＪＮＮの取材で分かりました

Translation:

According to the JNN report, at Fukushima daiichi reactor #1, there is hardly any water in the pressure vessel and in the containment vessel outside the pressure vessel.

It doesn't help that they are not very precise with wording later in the article:

また、外側の格納容器にもほとんど水がたまっていないことが、政府関係者への取材で分かりました。原子炉に水を入れる作業は続いていますが、水は格納容器の外に漏れている可能性が高いということです。

Literal translation:

Also, it was found through an interview with the government officials that outside of the containment vessel there is almost no water.

Although the process of injecting water to the reactor is continuing, it is a high possibility that the water is leaking to outside the containment vessel.

They use the word 格納容器 "containment vessel" which doesn't make sense. I would have thought they should have used 圧力容器 "pressure vessel".

 

[Jim Lagerfeld]

Tthe original news in Japanese on MBS only says "hardly any water" (http://www.mbs.jp/news/jnn_4723222_zen.shtml ) :

福島第一原発の１号機で、圧力容器やその外側の格納容器にほとんど水が溜まっていないことが、ＪＮＮの取材で分かりました

Translation:

According to the JNN report, at Fukushima daiichi reactor #1, there is hardly any water in the pressure vessel and in the containment vessel outside the pressure vessel.

It doesn't help that they are not very precise with wording later in the article:

また、外側の格納容器にもほとんど水がたまっていないことが、政府関係者への取材で分かりました。原子炉に水を入れる作業は続いていますが、水は格納容器の外に漏れている可能性が高いということです。

Literal translation:

Also, it was found through an interview with the government officials that outside of the containment vessel there is almost no water.

Although the process of injecting water to the reactor is continuing, it is a high possibility that the water is leaking to outside the containment vessel.

They use the word 格納容器 "containment vessel" which doesn't make sense. I would have thought they should have used 圧力容器 "pressure vessel".

The press conference was a little more specific, as the MBS leak came by way of a 'confidential source' ahead of the official announcement.

My understanding of the official version of events:

They re calibrated the water gauge for the pressure vessel. The re calibrated gauge now reads no water. The gauge bottoms out at 5m below the top of the fuel rods, leading them to conclude that the current water level is more than 1 m below the bottom of the 4m long fuel rods. This leads them to conclude that the fuel has melted and slumped to the bottom of the pressure vessel. The measured temperature at outside of the bottom of the pressure vessel is still around 130 degrees, leading them to conclude that there is still some water cooling the damaged fuel, but at a level of less than "-5000mm" to use the TEPCO scale, hence the somewhat ambiguous phrasing.

 

[GJBRKS]

Where do they say that? I can't find that part about "100 percent fuel melt" in the provided links.

Moreover, it's a mystery for me. In several aspects. Former assessments of Mark 1 Containment security (provided by NUCENG) reported that an uncovered core would breach the reactor vessel in less than one hour.
Now we learn that Unit was likely uncovered for two months. Yet there were no indications of any breaches.
Furthermore, as EX-SKF pointed out in his blog, where the hell did the water go? They pumped thousands of tons of water inside the RPV and now there's hardly any left. Highly contaminated basements were reported for Units 2 and 3 afaik, but NOT for Unit 1.
And I was just thinking that at least with Unit 1 we were sure what's going on...

So I'd like to ask one question:

- Why DIDN'T the RPV and containment fail big way (Corium relocation through the basement and in the earth) when the core was uncovered for months? Is the Mark I containment in the end not as bad as everyone says?

The core probably was not uncovered for long , it just vertically shifted a couple of meters , there's still water there to cool it.
Pressure has been stable , temperatures are dropping

 

[ihatelies]

About the hole theory, first of all I stand corrected the picture summited was new (to me at least) , having said that I toke a look at the same spot under 3 different but close angle , and I can not see that as a hole made by an inner force. Some of the roof structure is missing some are bent , but in my repeated opinion not in the suggested way
[PLAIN]http://k.min.us/jntf3c.jpg[/QUOTE]

Ahh, thank you for doing this. I see the hole in each one of your view, although several here have pointed out that my original vies shows it most prominently..

By saying you do not think it came from an inner force - you mean that you do not believe something from the inside caused the damage?

Seems like that's a common opinion here - however I'd like to understand what it is based on, because everything about the hole suggests to me that it came from an "inner force". In fact, it is almost a textbook example of "explosive forming" of metal.

Something must have formed that hole. I've speculated that it was something out of the reactor, but others disagree, and that is not a problem. If the reactor plug, cap and pressure vessel can be shown to be intact, then it must have been something else - if they're not intact, then this is where stuff exited on it's way skyward.

The first check would be the alignment with the reactor core - As I've said earlier, if the reactor is centered in the building on a North South axis, then this hole was likely not caused by anything in the reactor containment itself. However if it is offset by a few meters to the south, then the hole lines up very well.

The second check would be whether the single crosstie that appears to span the hole from one truss to the other, is attached to both trusses. If it is attached at both ends, it heavily negates my "hole " idea.

 

[NUCENG]

Thanks for that Nuceng. I take it when the nuke accident first occurred and Japan reached out to the US for aid, it was the military and GE that was recommending to expand the no-go zone and shut all GE reactors down (on the island) to inspect the known weak points, anybody else were just sock puppets.

Sorry, I don't know about contacts between TEPCO or the Japanerse Regulators with GE other than what is posted on the GE website. I highly doubt that the US military was involved in evacuation decision-making. According to reports they provided support and supplies and helped in environmental surveys wih helicopters. Japan now builds their own plants and how much direct involvement GE has for new plants is unknown. Their connection with AREVA is pretty strong, but again, I can't say how much.I have seen reports that the NRC team that went to Fukushima recommended more evacuations. The Russians have offered help.

The No-Go area was not an early decision. Didn't that happen late April? Do you have a link about shutting down all GE reactors? I know Prime Minister wanted Hamaoka to shutdown, but hadn't seen a general shutdown discussion. That is a political decision and may be the correct move in Japan considering the significant issues that have emerged. Clearly they need to reconsider the tsunami risk. It would be a tough go for the Japanese economy, so a decision like that would need some strong leadership. My last information was that the utility refused to shutdown Hamaoka, so leadership or authority is so far missing.

Haven't seen anything about sock puppets. Not sure if they could help, but maybe they could be used for cleanup.

 

[~kujala~]

Highly contaminated basements were reported for Units 2 and 3 afaik, but NOT for Unit 1.

Yes, but in the turbine buildings. Perhaps the water in the unit 1 has gone into some areas of the basement of the reactor building and for some reason not into the turbine building. This contaminated area could still be unidentified. And some of the water may have escaped as steam.

BTW: I-131 rising underneath unit 1, hopefully temporarily?
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110510e3.pdf

 

[jlduh]

With all the reporting mistakes Tepco made in the past and corrections for which they were officially reprimanded, I am sure that the water level findings were double and treble checked before releasing to the public and involving the Chief Cabinet Secretary Yukio Edano. Tepco cannot afford to come tomorrow and apologise once again that a mistake has been made with such a serious issue.

Now clarity has to be given on the pressure readings of the reactor vessel, how can one have a leak and record pressures of 0.4 and 1.3MPa_abs (A and B channels)

Well, i see that progressively "moderate" members start to be upset by what they discover day by day and weeks after weeks... Your remark is perfectly right AntonL: one bad reading is possible, but how can you explain so many bad readings?

One month and a half ago i was explaining in one of my posts here (and that's why i started the "more political thread") that even if we are seriously attempting here, on this physics forum, to stay scientific and have a rational approach of things as much as possible, this understandable desire would be, as things will developped, undermined by the fact that the infos, on which we base most of our efforts and reflexions, are far for reliable also because they are issued by one unique source (Tepco) which is NOT neutral (in the meaning of some "scientific neutrality" concept) in this desaster.

Tepco, a private company, lost almost 80% of its stock value, and again almost 9% yesterday when this info about N°1 reactor was given, they seek help from the government (9 billions euros) otherwise they will go bankrupt very quickly. The next meltdown will be the meltdown of the company itself, from the company, no way a private company can handle such a disaster over the long (very LONG indeed!) run. It'a a matter of weeks or month before, one way or an other, this company will be nationalized (saying it openly or not, but that's pure politics dependent).

Having said that, how can we believe that a good scientific work can be done based on their datas? How can neutral scientific approach from their standpoint can stay alive when facing such a threat: the meltdown of the company itself? Just "jump in their shoes" for a second and imagine the pressure not only in the vessels (which is probably close to atmospheric in all of them now...) but also above their heads?

So my point is: how can people like us think of being able to do a good or even satisfactory scientific work based on sources that are in fact so unreliable and weak? I have my own answer from the beginning (time will prove if I was wrong or right) but I let people here meditating about this... I'm not negating all the efforts her, I'm just trying to explain that some salt and pepper should be put in the mixture to avoid big misleadings.

For sure Tepco is going to come very quickly in front of the press and... apologize!

The real and interesting question is: apologize for what?

For hidden datas? For lack of professionalism cross-analysing and interpreting the FULL SET of data? For lack of consistent communication to press and public? For a new mistake if they come back and say: no no, there is water inside the RPV 1, we made a (NEW) mistake annoucing it was uncovered? For misleading brilliant (some, not me!) members of PF forum to deadends and making them spend a lot of their time anylizing what ends up being no go theories?

For... (list to be completed).

 

[Rive]

The original news in Japanese on MBS only says "hardly any water" (http://www.mbs.jp/news/jnn_4723222_zen.shtml ) :

福島第一原発の１号機で、圧力容器やその外側の格納容器にほとんど水が溜まっていないことが、ＪＮＮの取材で分かりました

Translation:

According to the JNN report, at Fukushima daiichi reactor #1, there is hardly any water in the pressure vessel and in the containment vessel outside the pressure vessel.

It doesn't help that they are not very precise with wording later in the article:

また、外側の格納容器にもほとんど水がたまっていないことが、政府関係者への取材で分かりました。原子炉に水を入れる作業は続いていますが、水は格納容器の外に漏れている可能性が高いということです。

Literal translation:

Also, it was found through an interview with the government officials that outside of the containment vessel there is almost no water.

Although the process of injecting water to the reactor is continuing, it is a high possibility that the water is leaking to outside the containment vessel.

They use the word 格納容器 "containment vessel" which doesn't make sense. I would have thought they should have used 圧力容器 "pressure vessel".

Thank you for the translation. Is the referenced JNN report available somewhere?

Anyway, this 'no water' scenario is not consistent with any other data available (temperature, radiation, pressure) so I think that this one (two) instrument(s) gone mad and not all the others. Without water that reactor would look like U3: hot bottom, continuously climbing temperature. And even the U3 with its heavier load took a few days to reach its actual state. So I think this 'full meltdown' or 'full core collapse' is also unlikely in case of U1.

Actually, how are those gauges works?

 

[jlduh]

Ok now let's list what new questions are raised IF WHAT TEPCO REVEALED IS TRUE AND IF THEY DON'T COME BACK TO APOLOGIZE FOR A NEW MISTAKE ABOUT THIS (who knows?):

1- if what used to be the core in N°1 has totally relocated at the bottom of the RPV, how can all the parameters given by TEPCO be interpreted? Total BS?

2- the same question applies to the 2 other reactors (2 and 3): are this parameters relevant to assess the situation or can it be considered like for N°1 as total BS? Then i have to admit that one of the "proofs" that N°3 reactor was still there in a "close to normal shape" is clearly weakened because of this revelation...

3- based on the amount of fuel initially inside the reactor N°1, plus the volume of the "other stuff" inside (control rods, etc.), is it even physically possible, from the volume standpoint, based on the dimensions of the RPV and its layout, that ALL the fuel has enough room to relocate below the "1m below the bottom of fuel rods" level? This calculation has to be done to assess if what TEPCO says is consistent with reality and IF WE CAN THEN ASSUME that NO MELTED FUEL/LAVA LEAKED OUTSIDE OF THE BOTTOM OF THE RPV. If there is not enough room, then at some point it would probably mean that some lava leaked outside.

4- considering what is below the RPV, the drawings and sketches we have indicate that there is below it what is called sometimes "reactor cavity" where sits all the control rods mecanisms and some other stuff.

http://www.netimago.com/image_199258.html

http://www.netimago.com/image_199265.html

http://www.netimago.com/image_199266.html

The question is: do we think this cavity is now full of water coming from:

A) the containment vessel around (which is supposedly flooded to some level) whatever path the water folllowed (leaks, etc.)

or

B) the leaked RPV (bottom) especially through control rods bores or any other leakage there.

5- If this cavity has water in it, and if it is a quite closed cavity (concrete around) then any drop of lava from RPV could create a new feared steam explosion.

But who knows, maybe there is already some lava there? The calculation of point number 3- is a first check for this assessment.

6- how can such a mass of melted/damaged fuel relocated at the bottom of the RPV can still be "cooled" by only sitting water above it? In TMI meltdown, only half of the core was melted and relocated, but more than 1 meter below the bottom of fuel rods levels, this is a 100% damage and relocation.

 

[AntonL]

Furthermore, as EX-SKF pointed out in his blog, where the hell did the water go? They pumped thousands of tons of water inside the RPV and now there's hardly any left. Highly contaminated basements were reported for Units 2 and 3 afaik, but NOT for Unit 1.
And I was just thinking that at least with Unit 1 we were sure what's going on...

Yes, but in the turbine buildings. Perhaps the water in the unit 1 has gone into some areas of the basement of the reactor building and for some reason not into the turbine building. This contaminated area could still be unidentified. And some of the water may have escaped as steam.

BTW: I-131 rising underneath unit 1, hopefully temporarily?
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110510e3.pdf

here are the water level measurements http://www.nisa.meti.go.jp/english/files/en20110511-2-6.pdf , Started the transfer of the water from the trench of Unit 2 to the basement of the Radioactive Waste Treatment Facilities. (Main Building) (Apr. 19 from 10:08 about 10m³/h) but this has little effect on the water levels

Below the plots from this data and one notes quickly theta Unit 2 to 4 trenches and Basements are closely linked. Unit 1 basement is constant at +5050 OP that is 150mm flooding as basement floor is +4900 OP, Units 2 to 4 basements are flooded by around 1400mm as basement floor is +1900 OP.

But most strange is the sudden falls in Unit 1 trench, where has this water gone? ( 3 occasions by 400mm)
There has been no reporting of transferring Unit 1 trench water.
Into the sea? tanked by aliens ? it just does not make sense!
Does Tepco really not query their results - they must be prepared for logical explanation when asked

[PLAIN]http://k.min.us/ikXNrI.JPG

[PLAIN]http://k.min.us/ilcO06.JPG

 

[PietKuip]

BTW: I-131 rising underneath unit 1, hopefully temporarily?
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110510e3.pdf

That looks like another typo in an exponent.

Such errors are rarely corrected. Tepco's quality control is pretty worthless.