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Nuclear accident follows Japanese earthqauke
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mr brightside



Joined: 01 Apr 2011
Posts: 224
Location: On the fells

PostPosted: Wed Jul 13, 2011 7:39 pm    Post subject: Reply with quote

DominicJ wrote:
Mr Brightside
A woodburning boiler has to be passivly cooled, so the boiler sits on the floor, and suspended above it, is a big water tank, the boiler heats the water in contact with it, the warm water rises, and is displaced by cool water from the top, which is warmed up and displaced by the cooler water from above and the cycle continues, until either the cooler water at the top is no longer cool and the water tank explodes, or the reactor is unable to keep the entire volume of water boiled, so its safe.

Basicaly yeah, giant radiator.


I understand. Found this...



What i failed to grasp was the concept of the water in the tank not actually entering any of the reactor cooling pipework, company PCs censor google images. Looks like a reliable system as long as the water isn't in danger of running out, just not very earthquake proof and quite fragile in that respect. Mind, our earthquakes aren't that severe.

Edit: Err balls that's not an AP1000 installation, same theory maybe?
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An Inspector Calls
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Joined: 27 Jan 2011
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PostPosted: Sat Jul 16, 2011 2:44 pm    Post subject: Reply with quote

I see there's been some concern about provision of emergency cooling water for passively cooled reactors. I can't verify this for all such reactors, but the UK magnox reactors (which were passively cooled) all had huge, on site, town's water reservoirs for just such a purpose.

Just checked: Wylfa's is still there.

No reason why type III+ PWRs shouldn't have a similar provision.
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An Inspector Calls
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PostPosted: Sat Jul 16, 2011 2:46 pm    Post subject: Reply with quote

kenneal wrote:
What human design error is going to be made in the UK reactors or are UK or French design engineers less human than Japanese ones?


Ah well, they'll employ people like biff and your goodself to think of all the nasty things that could happen, and then they solve them all!

Simples.
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raspberry-blower



Joined: 14 Mar 2009
Posts: 1453

PostPosted: Sun Jul 17, 2011 8:20 pm    Post subject: Reply with quote

Meanwhile, back at Fukushima, working conditions are as grim as ever:

Quote:
Workers are struggling under intense heat at the crippled Fukushima Daiichi nuclear power plant with as many as 31 people having fallen sick complaining of apparent symptoms of heat stroke, according to Tokyo Electric Power Co. While the utility, which operates the plant, has taken steps to ease labor conditions such as shifting work hours, they are apparently not enough. Sweat begins to build up inside masks, for instance, within seconds of them being donned.
Workers also appear to feel pressured and refrain from taking sufficient breaks for fear of slowing down work to contain the crisis.
Article continues

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mr brightside



Joined: 01 Apr 2011
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Location: On the fells

PostPosted: Mon Jul 18, 2011 3:30 pm    Post subject: Reply with quote

Positive pressure masks and BA would be far better for them, canister masks are awful in heat.
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biffvernon



Joined: 24 Nov 2005
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PostPosted: Wed Jul 20, 2011 7:20 am    Post subject: Reply with quote

They are expecting 200mm of rain over the next 24 hours.
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biffvernon



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PostPosted: Wed Jul 20, 2011 6:56 pm    Post subject: Reply with quote



Looks like the rain washed some of the contamination away.
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An Inspector Calls
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PostPosted: Thu Jul 21, 2011 9:50 am    Post subject: Reply with quote

kenneal wrote:
DominicJ wrote:
Mr Brightside
If the core is passivly cooled, there would be the core, and a water store above it.
Make the water store big enough so the core can dump everything into it with just atmospheric cooling.



Some of the French inland stations have had to be shut down because of low water levels during periods of drought. the cooling volumes a huge, Dom. What would you do in an emergency, boil the dammed water?


You clearly don't understand the difference between the cooling requirements for normal operations (thermal power perhaps >2GW) and shutdown/emergency cooling (thermal power <100 MW, and falling within a few hours to <10 MW).
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biffvernon



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PostPosted: Tue Jul 26, 2011 6:51 pm    Post subject: Reply with quote

Try post #10708 at http://www.physicsforums.com/showthread.php?t=480200&page=670
Suggesting the tsunami was not so much to blame.
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RGR
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PostPosted: Tue Jul 26, 2011 11:53 pm    Post subject: Reply with quote

[quote="biffvernon"]

Last edited by RGR on Fri Aug 12, 2011 7:00 am; edited 1 time in total
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biffvernon



Joined: 24 Nov 2005
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PostPosted: Sat Jul 30, 2011 8:10 am    Post subject: Reply with quote

Some places get all the luck:
Quote:
Fukushima hit by torrential rains

Torrential rain in Niigata and Fukushima prefectures in northern Japan has caused rivers to overflow, raising the danger of landslides.
Authorities have issued an evacuation order or advisory to about 400,000 people in 22 municipalities.
In Niigata's Sanjo City, more than 10,000 people were ordered to evacuate after a dike collapsed.
A 67-year-old man in Niigata Prefecture was found in a stream and later confirmed dead. 5 people are missing in the region.
Since Wednesday, more than 650 millimeters of rain has been recorded in some parts of Fukushima. Niigata has gotten more than 600 millimeters.
The flooding will also, presumably, move radioactive soil into new locations.

http://crofsblogs.typepad.com/h5n1/2011/07/fukushima-hit-by-torrential-rains.html
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biffvernon



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PostPosted: Tue Aug 02, 2011 7:50 am    Post subject: Reply with quote

Quote:
Plant operator Tokyo Electric Power (Tepco) reported Monday that radiation exceeding 10 sieverts (10,000 millisieverts) per hour was found at the bottom of a ventilation stack standing between two reactors.

Tuesday Tepco said it found another spot on the ventilation stack itself where radiation exceeded 10 sieverts per hour, a level that could lead to incapacitation or death after just several seconds of exposure.

http://www.reuters.com/article/2011/08/02/us-japan-nuclear-radiation-idUSTRE7710XB20110802
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Ippoippo



Joined: 24 Nov 2005
Posts: 255
Location: Bath->Tokyo->Cardiff-> Hokkaido, Japan next?

PostPosted: Tue Aug 02, 2011 8:56 am    Post subject: Reply with quote

Some updated stats for March and April, figures released on 29th July.

http://www.mext.go.jp/component/a_menu/other/detail/__icsFiles/afieldfile/2011/07/29/1306949_072914.pdf

(You may need to download the Japanese font pack for Adobe Reader if you use that, it shows up OK in Chrome though. Also, text is in English and Japanese)

Also, note, the figures are measure in MBq per km squared per month (in case people didn't know that 月 in this context means month)
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biffvernon



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PostPosted: Thu Aug 18, 2011 8:43 pm    Post subject: Reply with quote

Things do not seem to be improving:

http://english.aljazeera.net/indepth/features/2011/08/201181665921711896.html
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emordnilap



Joined: 05 Sep 2007
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Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Fri Aug 19, 2011 10:06 am    Post subject: Reply with quote

Thanks for that Biff. A hell of an article, no more disturbing than it should be.
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