Nuclear accident follows Japanese earthqauke

Is nuclear fission going to make a comeback and plug the gap in our energy needs? Will nuclear fusion ever become energetically viable?

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Ippoippo
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Post by Ippoippo »

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biffvernon
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Post by biffvernon »

and http://cryptogon.com/?p=25810

So what they told us was impossible is happening after all!

Discussion at http://www.physicsforums.com/showthread ... 0&page=724
An Inspector Calls

Post by An Inspector Calls »

What are you on about? Radiation is detected at Kukishima: therefore, there's fission. You can't have radiation without fission. So what's the news?

I suppose you're thinking of criticallity, but since the nuclear material isn't in a moderated configuration (assuming it's been melted down) it's difficult to see how it can go critical.
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biffvernon
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Post by biffvernon »

Re-criticality is exactly what the Xenon 135 levels indicate.
Tokyo Electric Power Company, said that gas from Reactor No. 2 indicated the presence of radioactive xenon and other substances that could be byproducts of nuclear fission. The presence of xenon 135 in particular, which has a half-life of just nine hours, seemed to indicate that fission took place very recently....

But even in their most dire assessments, some experts had not expected even bursts of re-criticality to occur, because it was unlikely that the fuel would melt in just the right way — and that another ingredient, water, would be present in just the right amounts — to allow for any nuclear reaction. If episodes of fission at Fukushima were confirmed, Mr. Koide said, “our entire understanding of nuclear safety would be turned on its head.”
http://thinkprogress.org/romm/2011/11/0 ... -its-head/

The discussion by the physicists continues at http://www.physicsforums.com/showthread ... 0&page=726
An Inspector Calls

Post by An Inspector Calls »

No it doesn't, it indicates fission.

A reactor goes critical only when the replication of released, fission neutrons generation to generation reaches 1.

If it's below 1 the reactor is sub critical, if above it's super critical and the radiation levels will start to multiply (a key measurement then is doubling time which is why reactors are always fitted with doubling time trips).

But the reactor, if it has melted down, is no longer in a configuration where the fissionable uranium can achieve criticallity - it's lost the moderator and thus the quantity of thermal neutrons (as opposed to fast neutrons) has fallen.

These points are mentioned in the physics forum.

There may be zones in the melted lump where, as it cools, neutron replication increases from time as it physically shifts or if neutron absorbers, such as xenon, decay to other fission products. There's no new physics.
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biffvernon
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Post by biffvernon »

The truth is leaking out from TEPCO, rather more slowly than the fuel did.

http://www.guardian.co.uk/world/2011/de ... ely-melted
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biffvernon
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Post by biffvernon »

Here's an interesting video with the new Japanese prime minister explaining just what 'cold shutdown' means. He admits the most, if not all, the fuel melted and went through the floor and it's exact location and temperature are unknown. Cold shutdown means that the whole thing is generally under 100 degrees but that doesn't amount to 'control'.

http://www.youtube.com/watch?feature=pl ... xUQKJwkIeY
Ippoippo
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Post by Ippoippo »

This is rather worrying footage.

http://www.youtube.com/watch?v=kHXXa_QOET8
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biffvernon
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Post by biffvernon »

Getting on for a year on and the summing up accounts are emerging.

http://www.globalresearch.ca/index.php? ... &aid=28870

Fukushima: A Nuclear War without a War

The Unspoken Crisis of Worldwide Nuclear Radiation

Michel Chossudovsky (Editor)
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PS_RalphW
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Post by PS_RalphW »

Quite a good documentary on BBC2 last night, probably on iplayer now.

Extended interviews with workers, politicians and management, about how close the reactor cores came to exploding, and the release of spent fuel in one of the explosions, and at one point the director of the plant called for its total abandonment, ordering all staff to leave, as he saw total meltdown as unavoidable.

No discussion of what the current status is, or what next... implied a 20 year exclusion zone in the immediate area.

http://www.bbc.co.uk/programmes/b006mgxx

Inside the Meltdown
Last edited by PS_RalphW on 24 Feb 2012, 09:43, edited 1 time in total.
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JohnB
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Post by JohnB »

RalphW wrote:No discussion of what the current status is, or what next... implied a 20 year exclusion zone in the immediate area.
Probably a good thing I don't live much less than that distance from Hinkley Point any more!
John

Eco-Hamlets UK - Small sustainable neighbourhoods
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biffvernon
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Post by biffvernon »

Life in Japan a year on as the world's biggest clean-up is attempted.

http://www.bbc.co.uk/news/world-asia-pacific-17321936
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biffvernon
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Post by biffvernon »

And a nice little film via People Tree: http://www.youtube.com/watch?v=tLSiJDO99c4 with some interesting insights into how folk are coping, the media and how to cope without nuclear power.

Part 2: http://www.youtube.com/watch?v=fqZDvWtHOb8
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biffvernon
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