Monday, August 8, 2011

Japanese Researcher Says Reactor 3's Fuel Melted Twice, Dropped to Containment Vessel

From Asahi Shinbun (3:02AM JST 8/8/2011; not the literal translation):

Fumiya Tanabe, former head of the research at Japan Atomic Energy Agency, will present the result of his research on Reactor 3 at Fukushima I Nuclear Power Plant in the upcoming Atomic Energy Society of Japan's conference next month.

Tanabe thinks the fuel melted and dropped to the bottom of the Reactor Pressure Vessel of Reactor 3 by March 14's explosion; then the melted fuel stayed there, cooled by more than 300-tonnes/day water. However, the amount of water injected dropped to only 24 tonnes per day from March 21 to 23, and 69 tonnes per day on March 24, probably due to increased pressure within the RPV.

It caused the melted fuel to heat up again, and the fuel melted through the RPV and dropped onto the Containment Vessel (pedestal; see the diagram from Asahi).

According to Tanabe, the amount of water from March 21 to 24 was only about 11 to 32% of what was needed to remove the decay heat, and within one day the melted fuel would attain the melting temperature again.

Tanabe thinks this massive "re-melting" caused the release of a large amount of radioactive materials into the environment which caused a spike in air radiation in wide areas of Tohoku and Kanto including Tokyo, and most of the re-melted fuel dropped from the RPV to the Containment Vessel.

The article doesn't say what Tanabe thinks has happened to the melted fuel that dropped onto the Containment Vessel since.

But the article does say this:


TEPCO hopes to have a "cold shutdown" where the temperature at the bottom of the RPV is low [below 100 degrees Celsius] as the target for winding down the nuclear accident. But if the fuel core is mostly melted and has dropped down to the Containment Vessel, it may affect the "roadmap".

No kidding. Yes it may. Where have you been, Asahi, for all these months? Is this news to you?

Tanabe's chart (from Asahi article) plotting the air radiation level (in microsieverts/hour) shows a spike on March 21. It rained that day in Tokyo.


Anonymous said...

Three things cannot be long hidden

Anonymous said...

There are a bunch of holes in the bottom of the reactor vessel for all the control rods, since boiling water reactors have a steam generator in the top that prevents the control rods from being on top. Each of these rods is sealed, I believe, with graphite. I think it is more likely that the seals failed than that the reactor vessel itself was breached. In contrast, at Three Mile Island, the reactor was a pressurized water reactor with the control rods at the top and NO holes in the bottom, so there was no breach of the reactor vessel by the complex mixture of stuff that ended up at the bottom of the reactor vessel at TMI.

Anonymous said...

I think that it rained in tokyo the 15 or 16 of March as well, when the radiation was at it highest. Black rain in Tokyo. Isn't it the 17 that it was announced that the tap water was too full of iodine to be drunk by young children for tokyo?

Anonymous said...

I thought the rods were sealed with zirconium?

Anonymous said...

These things are now runaways,in a few million years another civilisation of another species may have the same sense of wonder that the water modulated Oklo in Gabon generated.

citizenperth said...

In that we are screwed is not our fault. We were elad to believe smoking was cool, Radiation was transient, and science had an answer for everything.

God was always a non-plus.

A well, I am a Deitist, so I don't care. To everything turn turn.

Mankind threw his chips away when he decided to see who had the bigger penis.

Anonymous said...

Cold shutdown? It's like TEPCO trying to turn off the Sun...good luck!

Oh, and as far as the "Roadmap", it's a cartoon map that looks like Buggs Bunny drew it!

That's All Folks!

Anonymous said...

Calling King Canute!
Time to roll back the tide.

jay said...

Id like to see the Japanese eat dolphin now. Mercury and radio particals. A double wammie, cocktail of death. Every marine sport fisherman should measure, tag, and then release large fish indicating level of rad measured with date. I suppose dolphin too but they'd eat them first. Edgar Cayce once said the greater of Japan must fall into the ocean. Not that it will but must, some clarity presents itself now.. Bon appetite my little yellow friends.

All in all, the LFTR design is most promising technology for power at large scale, safe too.

Anonymous said...

".. now .. Bon appetite my little yellow friends."

.. says the bemused Japanese to all downwinders?


the voice in your head said...

Hiya Marc,

Graphite? Uh, that's something from Chernobyl. Zircaloy tube on top of stainless steel cladding is more like it.

Anonymous said...

Well no,it was like what do we call this insane situation?


It means they more or less knew what it was but now it has become uncertain,in time this uncertainty won't matter so much as they had 10 to 15 years before senilty of death claimed them,no idea what to do in the meantime.

The thinking was to forget about it,move state and invest in more Nuclear facilities and for press interviews pretend it never happened.

Anonymous said...

This would also be a Plutonic Corium.

Presumably differing from other Coria due to the composition of the sea water moderator,as well as the Plutonium and the lifecycle state of the fuel rods at the time of detonation and/or meltdown.

I'm guessing the fission suppression rods are also a component.

Anonymous said...

It rained Tokyo & Chiba first time since 11 Mar on 21 March. The particles must have been in the atmosphere all this time, which is why we have not seen anything on the ground until 21st onward.

That doesn't mean the releases happened the day before or so. These are very light materials, no reason why they cannot stay up for a while and be blown here and there, then rain down.

However, other "experts" have also said that the large releases occurred not at the time of explosion, but some time afterwards.

Anonymous said...

You know how it is with Japanese beach resorts,one can sunbath even in the most inclement of weathers.

Anonymous said...

This photo shows the bottom of a boiling water reactor vessel as in Fukushima Dai-Ichi. The holes in the bottom are for the control rods. Each control rod is raised and lowered by a hydraulic system. A control rod drive mechanism design can be seen here:

SEO Company said...

The abandonment of radiation testing by the feds also comes on the heels of an announcement from a top environmental scientists that food across the entire United States will be affected by the Fukushima nuclear radioactive fallout and an analysis from Japan’s top nuclear expert that reactors 1, 2 and 3 have all suffered a complete nuclear meltdown.

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