Japan nuclear meltdown 'maybe worse than thought'

Dec 01, 2011
Black smoke rises from reactor number three at the Fukushima nuclear power plant, March 21, 2011. Molten nuclear fuel at Japan's Fukushima plant might have eaten two thirds of the way through a concrete containment base, its operator said, citing a new simulation of the extent of the March disaster.

Molten nuclear fuel at Japan's Fukushima plant might have eaten two thirds of the way through a concrete containment base, its operator said, citing a new simulation of the extent of the March disaster.

Tokyo Electric Power (TEPCO) said their latest calculations showed the fuel inside the No. 1 at the tsunami-hit plant could have melted entirely, dropping through its inner casing and eroding a concrete base.

In the worst-case scenario, the molten fuel could have reached as far as 65 centimetres (2 feet) through the concrete, leaving it only 37 centimetres short of the outer steel casing, the report, released Wednesday, said.

Until now, TEPCO had said some fuel melted through the inner pressure vessel and dropped to the containment vessel, without saying how much and what it did to the concrete, citing a lack of data.

"Almost no fuel remains at its original position," TEPCO said in the report.

Two other reactors at the Daiichi plant also went into when the tsunami knocked out at the plant.

Graphic showing how molten fuel rods may have burned two thirds of the way through a concrete containment base, according to new information released by Tokyo Electric Power company.

However, only about 60 percent of their fuel dropped through to the concrete floor and caused less damage, the report projected.

The molten fuel in the three reactors is believed to have stayed cool and stable because water has been injected into the vessels, the utility said.

TEPCO added, however, that it has yet to closely study many areas of the damaged reactors due to high level of and stressed its findings were based on modelling.

The exact position of the fuel believed to have eaten its way through the concrete and to what extent it is being exposed to the cooling water is not known.

"Uncertainly involved in the analysis is significant due to the uncertain nature of the original conditions and data used," the report said.

"Using (realistically assumed) conditions for the evaluation, the concrete could have been penetrated, but (the fuel) stayed inside the casing," it said.

Fukushima Daiichi has spewed radioactive materials across eastern Japan since it was inundated by the huge waves of March 11.

The world's worst nuclear disaster since Chernobyl in 1986 has not directly claimed any lives, but has left tens of thousands of people displaced and rendered tracts of land uninhabitable, possibly for decades.

TEPCO and the Japanese government have pledged to bring all the plant's reactors to a state of cold shutdown by the end of 2011.

Explore further: Far more displaced by disasters than conflict

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User comments : 13

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Tausch
3 / 5 (2) Dec 01, 2011
Everyone is curious what happens once the molten nuclear fuel finally leaves the last of all 7 security containments.

What is under the buildings? What were the buildings built on?
Does "cold shutdown" become meaningless in this scenario?
Will contact to bare earth cause an explosion?
encoded
5 / 5 (1) Dec 01, 2011
no explosion, just contaminates the water table
John_balls
5 / 5 (1) Dec 01, 2011
Not it's not worse then we thought. Plenty of experts said it was going to be really bad.
Mahal_Kita
5 / 5 (1) Dec 01, 2011
no explosion, just contaminates the water table


So.. Nuclear fuel that is so hot that it burns through concrete and steel will not cause an explosion? No nuclear explosion, no. But you'll have continuous (huge) explosions when the fuel reaches the water table. Something like a nuclear geyser..
rawa1
1.4 / 5 (8) Dec 01, 2011
We already know, the Japanese managed to dissolve whole nuclear reactor in marine water. Just twenty years after publishing of cold fusion technology.
Mahal_Kita
5 / 5 (1) Dec 01, 2011
Everyone is curious what happens once the molten nuclear fuel finally leaves the last of all 7 security containments.

What is under the buildings? What were the buildings built on?
Does "cold shutdown" become meaningless in this scenario?
Will contact to bare earth cause an explosion?


Your last question is a valid one. Even when the facility is built on solid rock, it will continue to burn through the rock. When enough water comes into the shaft for example, it will result in contaminating steam explosions. This will go on until this burning blob of nuclear fuel is cooled down enough. It's a blob now, no rods which you can cool in a controlled way.
Decimatus
3 / 5 (2) Dec 01, 2011
Why would contact with bare earth cause an explosion? That doesn't make any sense.

The main problem with a complete meltdown is ground water contamination. That is the nightmare scenario here.
Vendicar_Decarian
3.7 / 5 (6) Dec 01, 2011
The global nuclear powered paradise envisioned by Nuclear power Zealots would require the construction of 200,000 more of these power plants as well as thousands of breeder plants to produce the fuel needed.

It is an unworkable fantasy.

Skepticus
2.3 / 5 (3) Dec 02, 2011
The global nuclear powered paradise... is an unworkable fantasy.

Right. Nuclear God-like power should only be kept bottled up in billions-dollars nuclear warheads so we can always have our God-like Thor's hammer brandishing over the heads of upstarts who wants to use/perfect nuclear power for something else. Especially, the developing and perfecting part! If once it is known that safe nuclear is not only possible but technically doable by any country with reasonably competent industrial base, our God-like power will go down the toilet. It is absolutely good to be able to bully, rater than to be bullied! "Never again" will be engraved on every warhead!
Nanobanano
2 / 5 (4) Dec 02, 2011
Everyone is curious what happens once the molten nuclear fuel finally leaves the last of all 7 security containments.

What is under the buildings? What were the buildings built on?
Does "cold shutdown" become meaningless in this scenario?
Will contact to bare earth cause an explosion?


No, it pretty much keeps melting through the foundation and through the crust of the Earth until it runs out of energy or gets mixed and dilluted in the magma it makes out of the concrete and soil.

Yeah, contaminating everything along the way, namely the water table and anything down stream, both above and below the surface.
Isaacsname
5 / 5 (1) Dec 04, 2011
I kind of thought this would happen. When the Tsunami originally hit, I spent several weeks reviewing how the plant was built, my main thoughts were about how tidally-influenced capillary actions of groundwater under the plant might slowly leach contaminants out.

I'm still waiting for somebody to realize that Fukushima is actually a major stop for migrating fish, mammals, bugs and more. All you guys/gals should check out migratory pathways on that side of the world, the East-Asia Flyway is one.

Hell, there are pacific salmon that come all the way from Japan to swim hundreds of miles into the West coast of the US for example.

Jimee
1 / 5 (1) Dec 04, 2011
Let's find a way to start a nuclear war so we don't notice the little Fukushima problem anymore.
Callippo
1 / 5 (2) Dec 04, 2011
Why not to start with cold fusion instead? We will become rich and we could forget all these nasty problems of nuclear energetic - not just this little of Fukushima. You people should realize, what is better for us. Why to destroy everything we created in the last century just because we cannot face the new reality? We are like the people, who are willingly dying at desert in the shadow of bottled water vending machine. Such a catatonic resignation is really striking: we can build a skyscrapers, we can organize cosmic flights at Moon - but we cannot organize the research of silly simple technology, because we do believe in the opposite.

It just illustrates, how strong destructive force the intersubjective religion can be.