Wednesday, November 30, 2011

#Fukushima I Nuke Plant Reactor 1: TEPCO and NHK's Obfuscation on Corium in the Concrete

In the first post on the subject, I translated what NHK reported:


It has been discovered by TEPCO's analysis that the significant amount of Reactor 1's melted fuel pierced through the steel Reactor Pressure Vessel and dropped onto the Containment Vessel, then melted the concrete at the bottom of the CV. It is estimated that the melted fuel may have eaten into the concrete to maximum 65 centimeters deep.

Maximum 65 centimeters deep from the bottom of the concrete floor, right?

Well no. It's 65 centimeters from the bottom of the deep groove on the concrete floor.

And neither NHK nor TEPCO would bother to tell you how deep the groove is.

At least, NHK Kabun (NHK's last remaining conscience, as far as I'm concerned) tweeted and gave the link to its blog post, where NHK's analysis of the concrete-eating corium is shown with the screenshots from the program:

The text below the screen says: "In the worst case, it [the corium] may have reached 65 centimeters from the surface of the concrete. Where the concrete is the thinnest, it may have reached within 37 centimeters from the steel plate [of the Containment Vessel].

The "surface of the concrete" turns out to be the surface of the bottom of the groove that is X centimeter deep.

It's one thing for TEPCO's Matsumoto to say "surface of the concrete" (as we've gotten used to hearing technically correct explanations from him), but for NHK to say so while showing the graphics indicating it is the surface of the bottom of the groove is at once deceptive and covering its behind. NHK can now say "We showed it in the graphics that it was 65 centimeters from the bottom of the groove, and people should have paid attention."

(I'm asking NHK Kabun if they know the depth of the groove, but does anyone know or have access to a schematic diagram with measurement?)

Well, it does look like the Institute of Applied Energy is more right than TEPCO in saying the corium has eaten 2 meters into the concrete. And perhaps people like Hiroaki Koide of Kyoto University and the engineers who designed the reactors at Fukushima I Nuke Plant may be more right than the Institute of Applied Energy, and the corium has indeed escaped the Containment Vessel long time ago.

As the wiki entry on "corium" states, the corium can eat into the concrete 1 meters in the first one hour, and several centimeters per hour afterwards:

The fast erosion phase of the concrete basemat lasts for about an hour and progresses into about one meter depth, then slows to several centimeters per hour, and stops completely when the melt cools below the decomposition temperature of concrete (about 1100 °C). Complete melt-through can occur in several days even through several meters of concrete; the corium then penetrates several meters into the underlying soil, spreads around, cools and solidifies.[3] During the interaction between corium and concrete, very high temperatures can be achieved.


Anonymous said...

I watched the reporting on NHK last night and found it clear that the corium is only 37cm from the outer ball-shaped steel hull.

henry said...

Can someone explain the above graphic better? The brown curved line is the outer wall of the metal containment vessel, right? I thought the concrete base was outside/underneath the metal containment vessel. The graphic shows the concrete is inside AND outside the wall of the containment vessel. How thick/deep is the concrete UNDER the vessel (not inside it)?

no6ody said...

henry, I *think* there is more metal inside the concrete base. It's not concrete all the way down, so to speak. Imo there is corium in the concrete, but there is probably more corium under the concrete too. In addition, the concrete base is probably damaged by earthquake, tsunami, and/or explosion(s). T3PC0 is managing the release of bad news--just a little at a time, mixed in with lies, exactly like BP did with the Macondo disaster. Eventually we will see some pix of the melt-thru, but it might take another few years.

Anonymous said...

How would/will we know if the corium gets into the soil? I mean, what are we likely to see/understand/be coping with under such circumstances?

Anonymous said...

Don't think anyone knows..this is new territory for nuclear disasters.

Like the BP Oil Spill aftermath, Japan needs to appoint a new CZAR for Nuclear Meltthru Fukushima! Would have the same result..nada. Of course, the BP Playbook did not contain nuclear meltdowns...

Anonymous said...

Another graph. Clearly media is confused about what is what and measured how.


Anonymous said...

According to Yomiuri, the concrete floor is between 1.4 and 2.6 meters thick. That was a very vague estimate...

There is also an interesting line about the heat at the time of meltdown. It was the double of what would be needed to melt everything inside the reactor pressure vessel. So quite a lot of heat left over to do other unpleasant things.


Anonymous said...

The Wall Street Journal have their own version too. According to them, the fuel bored as deep as 2 meters into the 2.6 meter concrete base of the containment vessel. I am totally confused now.


Anonymous said...

"How thick/deep is the concrete UNDER the vessel (not inside it)?"

It seems to be 7.6 meters.

Yosaku said...


Per page 21 of the MAAP Analysis that you posted earlier, the depth of the sump pit is 1.2 meters.

Atomfritz said...

"It seems to be 7.6 meters."

Looking at the Tepco cartoons I also thought this first.

However, I am now less sure about this.
They could just have ommitted the cellar of the building in this simplified image.
However, if there is a cellar, the chances that corium melt through out of the building would be nullified, as it would be underwater in the cellar.

Anonymous said...

If TEPCO said it was a giant turd at the bottom of the reactor the sheeple would believe it, don't believe a word they say, the Corium is not far from the groundwater as we speak.

Mike said...

I find it curious that the lead to the WSJ article linked above says that the reactor "came closer to a catastrophic meltdown" than previously acknowledged. Am I missing something here? There has already been a meltdown, and the question is the extent of the progress towards melt through, right?


Mauibrad said...

What the hell is THAT?

Anonymous said...

I find it curious that the lead to the WSJ article linked above says that the reactor "came closer to a catastrophic meltdown" than previously acknowledged. Am I missing something here? There has already been a meltdown, and the question is the extent of the progress towards melt through, right?

yes, indeed. my guess is that once the article was written it was sent for one last check by the supreme content checker there whose job it is to make sure the bad facts don't get fully understood as such. So he, she (or it) rewrote the lead paragraph. The theory being that the reader will think right up front that 'yikes, that was close but at least there was no catastrophic meltdown!' Some won't get any further than that. Those that do will still have that lead teaser that we somehow got missed by that flying beer bottle - a narrow miss, but still a miss.

Mauibrad said...

WTF is THAT? #today

Anonymous said...

"WTF is THAT? #today"

Heavy duty welding? They have done some in the night hours before that were seen as red/orange flashes.

Criticality doesn't look like that, okay, if that's what you are thinking.

Nancy said...

We messed with this calculation earlier. Based on the elevation drawing of unit 1 the sump area is 609.6mm (aka 2 feet) deep. The elevation drawing shows only 1 sump, not 2 as TEPCO's presentation drawings. The photo I have of the pedestal area of unit 5 indicates that unit might have 2 sumps because you can see expanded steel over 1 side and what might be expanded steel on the other. The elevation drawing isn't 100% detailed so it could be the flaw?

Anonymous said...

About the corium melting the steel of the reactor vessel,

the graphite control rods insert into the core from the bottom of the reactor vessel so the corium does not need to melt thru the vessel steel to reach the concrete.

Graphite melts away, corium flows onto concrete.

Ivan said...

Graphite control rods? You are writing about Chernobyl RBMK nuke reactor? Water moderated reactor like ones in Fukushima don't have graphite control rods. You have, instead, neutron absorbing pellets within Zircaloy cladding. You can have oxidation of Zr in cladding in LOCA(loss of coolant accident) which will give hydrogen gas. But there is no graphite control rods anywhere!

BTW, graphite moderator in Chernobyl reactor accident did not melt away it caught fire.

beVivre said...

if you download the handout:
and view the grafics on pages 182 and 175 you can assemble the various informations.
182 - gives a closer/detailed display - comparable to the model above
175 - gives a wider illustration - showing the whole concrete 'block'.
According to this single grafic the total height of the concrete is 10.20m.
Into the upper part the metal containment vessel is embedded with its deepest point reaching down to 2.60m.
That leaves at this deepest point 7.6m of concrete underneath.
An inner height of 2.6m concrete is only given in the very middle of the vessel.
Left and right of this middle position the concrete has been excavated to produce two 'grooves' with a depth of 1.2m (width 1.45). So this only leaves a rest of max. ~ 1.4m at the inbound corners of the grooves but considerably less than that from the outbound corners to the steel plate.
According to the detailed and above grafic this is only 1.02m. And if 65 centimeters of this concrete is already molten then there's a rest-thickness of 35cm concrete before the metal vessel is reached.

Hoping that this rather non-scientific excursion is helpfull to get an idea of the offered builtup.
I personally think that the molten core(s?) has long since enhanced these positions by far and even digging their own individual paths. I wonder if this will ever be recognised or stay in the realm of wilde speculations.

Tip: on enenews xdrfox has already translated quite a lot of that pdf:

Ivan said...

Edit: I'm describing BWR fuel rods instead of control rods.

Control rods are still not graphite in BWR. Yes, inserted from bottom in BWR. Graphite tipped Inserted through top in RBMK.

Anonymous said...

Ivan, control rods are Silver-indium-cadmium alloys, generally 80% Ag, 15% In, and 5% Cd protected by a thin stainless steel cladding.

Ivan said...

Yes, that is correct for BWR control rod. Sorry English is not my first language and I write something on fuel pellets elsewhere at same time writing about control rods here.

Anonymous said...

If Zircaloy cladding on fuel rod has oxidized, around 2000 C, then stainless steel cladding on control rod is melted for sure.

Ivan said...

I should mention BWR control rods now contain hafnium but reactors at Fukushima are old piece of crap so I think 5:36 PM, you are more than correct about composition.

James said...

Regarding control rods, graphite and fuel leaks : the penetrations on the bottom of the pressure vessel that allow for the metal control rods to be inserted have graphite seats - this is a likely possible point of first failure. This is non-controversial, plenty of scientific papers have addressed it. You can see a diagram here:

"each control rod has a control rod drive mechanism (CRDM) that uses graphite seals to keep the water inside the reactor"

Anonymous said...

hey, i may not be able to see the corium in the soil, only all of the steam from the ground, BUT I can (still) see all of the oil in the Gulf from BP.

Ivan said...

"each control rod has a control rod drive mechanism (CRDM) that uses graphite seals to keep the water inside the reactor"

Yes, graphite seals, if they are still using them(old BWR have some upgrades done but it's not possible to specifically know what kind and which), would have been degraded if not obliterated when subject to this type of high heat.

But commenter wrote "the graphite control rods insert into the core", which is WRONG. BWR is not graphite moderated, thank God. Doesn't mean BWR SFPs at Fuku cannot catch fire. That's would be like mega-FUBAR then.

Anonymous said...


right you are on control rod composition. Now that memory serves the rods have graphite seals, and they certainly would have melted at 3000 C.

Is there any metal that can survive 3000 C in solid form?

Nancy said...

The control rods are not graphite as others have explained. From what we can find the graphite seals at the base of the reactor vessel were still in use at Fukushima. So they were likely the fail point for initial melt through. Like a big strainer. How fast the remaining steel melted is not fully known. TEPCO's melt down modeling ability is limited. Notice they came up with a nice neat scenario that allow them to claim fuel is still in containment. Then the next day they announce cold shutdown will be announced on Dec 16th. This is all a game and many experts have pointed out TEPCO doesn't have enough data to know exactly what has happened after meltdown.

Atomfritz said...

"...the rods have graphite seals, and they certainly would have melted at 3000 C.
Is there any metal that can survive 3000 C in solid form?"

Tungsten for example, melting point 3422 C.
Reactor grade graphite is extremely heat resistant, the reason why it is used for HTRs. Usual temperature in the pebbles can exceed 2000 C while the outer temperature is "only" 1400 C. The sources I found say it needs more than 4000 C to destroy/burn reactor graphite in inert atmosphere, but less with strong things like CO.

And corium doesn't need to be at 3000 C to become liquid. It's sufficient to have somewhat above 1500 C to make a liquid mixture of the metal rods and cladding with the UO2 and PuO2 mixed in. And then the convection and crust thermal isolation effects come in.
And steel doesn't melt quickly like butter as it's a good heat conductor.

You can see this in the cellar of Chernobyl NPS. There are several big tubes where corium flowed out without melting them. However, the photos revealed that the tubes softened and bent a bit.

Atomfritz said...


Dear arevamirpal::laprimavera,
I hope you are fine.

Could you please check this out and make an article about this scandal (if the story is true):

This blogger says that acute leukemia cases have increased sevenfold in Fukushima and part of Miyagi, and the health ministry quietly excluded these regions from their newly released health statistics survey.

If this is the new government's way to "prove" that health effects of the accident are nil, then this a beautiful scandal you really should investigate... Thanks in advance.

And thanks again for your great information work!

Ivan said...

"Reactor grade graphite is extremely heat resistant, the reason why it is used for HTRs."

I don't think they are using type of extremely heat resistant reactor grade graphite you write about, for seals in GE Mark I design. Specs from Japanese company that makes seals for nuclear valves Operation limit : 350 C, 17.2 MPa

So, with subjection to high heat, radiation, corrosive by-products...etc., it's right to assume graphite seals have failed.

Anonymous said...

Yikes. 350 Celsius! What an f'ing stupid design.

Ivan said...

"Is there any metal that can survive 3000 C in solid form?"

Atomfritz already answered. It's tungsten with melt point around 3400 C.

arevamirpal::laprimavera said...

@atomfritz, about link to the article about leukemia increased 7-fold,

1. The information has been flagged as "dubious" at best.
2. The article seems to co-mingle what's supposedly written as "translation" and the writer's opinion or guess, and quote the "citizen" without providing the link to the citizen's writing (there is such a link).
3. Link at the end as "source" only goes to the government page with links to statistics from varioius ministries. I don't know which source the writer is talking about.

There is no such thing as "national and public" medical associations in the alleged "news".

I'm looking for more credible sources on this.

Ivan said...

You can read about tungsten nuke applications(and other) from alloy product supplier in China. Most tungsten is mined there.

Mike said...

just a note here to thank areva for his efforts at comment moderation. the level of improvement in the content and tone of the discussion is dramatic. thanks also to the posters above for sharing their technical knowledge, thoughts and insights.

Anonymous said...

The General Arrangement Reactor Building Sections DWG NO. G-192417 displaying 'all main' building dimensions at some Daichii reactor, shows solid block under reactor vessel about 7m thick. Under torus, t shows 2m thick. Is it solid, I guess not. But at least that 2m ... Are there more detailed drawings? Sure. Will not be revealed for the public.

Anonymous said...

The very same DWG NO. G-192417 shows the dimension 2m60cm in the tepco handout being 4meters. Have fun.

Referenced facts sinking the fuku:


Anonymous said...


Anonymous said...

AREVA. Wouldnt it be hi time to delete the bs from the comments?

(I'm asking NHK Kabun if they know the depth of the groove, but does anyone know or have access to a schematic diagram with measurement?)

AREVA. If you really want an answer, the dimensional layout drawing is posted on my website, linky given above.

All who want to know, have to humble yourself and clic for Facts...

I wont tell b/c you encourage this sht on your blog comments 24/7 - or AREVA - is that sht from you?

Anyways, you have to measure yourself...

Kumachan said...

Hi Atomfritz,

About your post of December 2, 2011 8:50 AM and "leukemia hidden by government" you must know one very simple fact:
Leukemia induced by ionizing radiation takes a bit more than 9 years (average) to show up, it depends greatly on age, 5-6 years latency below 15 years old children and more than 20 years latency after 45 yo.
It`s hardly passed 9 months.
If the government wants to hide something, it should begin at least 5 years later.
I think you can now judge by yourself the seriousness of the claims you`ve read.
Leukemia came about a year earlier for those who got ARS, and therefore got some Sieverts!
Sorry I still didn`t reply to your old posts, I`ll try do to it by next we.
Search "leukemia hiroshima latency" then pick up medical websites.
And of course the prefectures in which 20thousands people died are left out of the statistics, because what you wouldn`t get the statistic of the average japanese people, but the statistic of the average japanese that survived the tsunami.
So, if most of the dead people were going to get leukemia, you are going to se a decreased percentage of leukemia. If most of the dead were healthier than average people, you are going to see worsened statistics (about the living).
BTW 1 Japanese out of 137 dies of leukemia in his/her life.
If you like to read similar science-fiction stories, I suggest you to look for "64 self defence dead 300 police dead 4300 tepco emploees dead Fukushima Medical College Radiation Research Unit".

Anonymous said...

"All who want to know, have to humble yourself and clic for Facts... "

You are displaying typical signs of being an obsessive compulsive EX-SKF blog commenter/ reader deliberately hell bent on annoying others. In order to remedy this you have to poke your own eyes out and lease a chainsaw and remove your hands! And after that you have to start reading your KJV 1611 bible some more.

Anonymous said...

"I wont tell b/c you encourage this sht on your blog comments 24/7 - or AREVA - is that sht from you?

Anyways, you have to measure yourself..."

Riiiiiiiiight. Next you'll be asking Areva to bend over to your backward demands.

Anonymous said...

No one has ever given out the specs for this fukusystem, purpose or accuracy. cost, computerization, personnel, structural integrity capable of using all power from the 6 nuke reactors unheard of.

Usage controlled by illuminati; Shimizu is/was hi level je§uit mason in papal NWO organization.

Utilization is thus left into ones imagination, here main issue is to show the structure and human forces behind… official explanation is bs. happy

stan said...

I guess that's another glass of plutonium for me. Bottoms up! Oops. I mean kanpai!

Anonymous said...

"Anyways, you have to measure yourself"

WTF???? Like with a measuring tape?

Ivan said...

Soooo, getting back to control rod questions it would originally be boron carbide (B4C) for old Mark I (Fuku type), and hafnium (Hf) for newer model BWR, or combo. Not silver-indium-cadmium alloys, that is for PWRs.

Control blade(cruciform) cracking is known problem in Mark I.

Interesting(f'ing stupid) desgn for sure. Cracking control blades, expanded graphite seals that fail at 350 C, control rod insertion from beneath, misalignment of control rods, cracking of shroud...etc.

Ivan said...

If anyone still interested to know more, I just found Fuku I reactors #3 and #6 are using thin hafnium blade within SUS316L stainless steel sheath. Stress cracking of blade sheath found in both reactors' control rods. That's one of things TEPCO was trying to cover up in 2002-2003.

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