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PostPosted: Sat Mar 19, 2011 10:58 
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I think you have failed to grasp the type and scale of back up generator.
When the main armature weighs seven tons, and ends up turning at up to 750 RPM, it doesn't just start up in a few minutes!

The back up generators are huge, and cannot be left without running up on a nearly daily basis.

Modern plants use gas turbines to power their backup generators for a quick start up to full power, but this plant used a huge battery back up to power the pumps while the generators got up to speed - and they soon failed when the generators failed to start - hardly surprising given their complete immersion in seawater!

It was not a question of contamination of the fuel or the diesel engines, but the electrical machinery.

This is the sort of scale involved - this is actually an electric motor, but the generator is fairly similar.
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PostPosted: Sat Mar 19, 2011 14:52 
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Apart from the generators, the transformers were immersed and the switchgear was torn away.
In any case, pumps that need to move 45 million KG/Hr of water are going to need a considerable amount of power.
The safety systems seem to be bombproof, although not 10-metre-tsunami proof:
http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Systems
Radiation, much mentioned of late has not seemed to reach Tokyo yet:
http://www.denphone.com/denphone-tokyo-office-geiger-counter

Quote:
Contrary to several news reports, the IAEA to date has NOT received any notification from the Japanese authorities of people sickened by radiation contamination.

In the report of 17 March 01:15 UTC, the cases described were of people who were reported to have had radioactive contamination detected on them when they were monitored.


http://www.iaea.org/newscenter/news/tsunamiupdate01.html

Quote:
Radiation Levels

* At 9:20AM (JST) on March 17, radiation level at elevation of 1000ft above Fukushima Daiichi Nuclear Power Station: 4,130 micro sievert.
* At 9:20AM on March 17, radiation level at elevation of 300ft above Fukushima Daiichi Nuclear Power Station: 87,700 micro sievert. At 11:10AM on March 17, radiation level at main gate (approximately 3281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power station: 646.2 micro sievert.
* At 7:50PM on March 17, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 3,599 micro sievert.
* For comparison, a human receives 2,400 micro sievert per year from Natural radiation in the form of sunlight, radon, and other sources. One Chest CT scan generates 6900 micro sievert per scan.

* Fukushima Daiichi Unit 1 reactor
* Since 10:30AM on March 14, the pressure within the primary containment vessel cannot be measured.
* At 12:50PM on March 17, pressure inside the reactor core: 0.185MPa.
* meters below the top of the fuel rods.At 12:50PM on March 17, water level inside the reactor core: 1.

* Fukushima Daiichi Unit 2 reactor
* At 12:25PM on March 16, pressure inside the primary containment vessel: 0.40MPaabs.
* At 12:50PM on March 17, pressure inside the reactor core: -0.027MPa.
* At 12:50PM on March 17, water level inside the reactor core: 1.8 meters below the top of the fuel rods.

* Fukushima Daiichi Unit 3 reactor
* At 12:40PM on March 16, pressure inside the primary containment vessel: 0.23MPaabs.
* At 6:15AM on March 17, pressure inside the suppression chamber was observed to fluctuate.
* At 7:00AM on March 17, pressure inside the suppression chamber: 0.22MPa.
* At 7:05AM on March 17, pressure inside the suppression chamber: 0.44MPa.
* At 7:10AM on March 17, pressure inside the suppression chamber: 0.26MPa.
* At 7:15AM on March 17, pressure inside the suppression chamber: 0.52MPa.
* At 7:20AM on March 17, pressure inside the suppression chamber: 0.13MPa.
* At 7:25AM on March 17, pressure inside the suppression chamber: 0.57MPa.
* At 9:48AM on March 17, a Self Defense Forces helicopter made four water drops aimed for the spent fuel pool.
* At 4:35PM on March 17, pressure inside the reactor core: 0.005MPa.
* At 4:35PM on March 17, water level inside the reactor core: 1.95 meters below the top of the fuel rods.
* At 7:05PM on March 17, a police water cannon began to shoot water aimed at the spent fuel pool until 7:22PM.
* At 7:35PM on March 17, five Self Defense Forces emergency fire vehicles shot water aimed at the spent fuel pool, until 8:09PM.

* Fukushima Daiichi Unit 5 reactor
* At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 145 degrees Fahrenheit.

* Fukushima Daiichi Unit 6 reactor
* At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 140 degrees Fahrenheit.


Up-To-Date:

http://www.jaif.or.jp/english/news_imag ... 33768P.pdf

External power from the grid has been restored to the reactor site and work will commence to activate the pumps....

The problem now is the spent fuel pool on unit four. Which, since the reactor had been de-fuelled prior to the accident, was full of highly active fuel rods. The temperature of which was 85C on 14 March.

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PostPosted: Sat Mar 19, 2011 18:30 
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Dusty wrote:
Quote:
The emergency pumps were under 30 feet of tsunami


Were they?

I may well have missed something (And will stand to be corrected if I have) but...

The reports I have read simply state that the back up generators "Stopped" an hour or so after the initial earthquacke triggered the reactor shutdown! I have not seen a specific explanation as to WHY they stopped! it just seems to be assumed that they were stopped by flooding (Though why they could not be restarted I do not know-though I have a theory)

Sadly my own experiance of back up generators is that they tend to be ignored until they are really needed! If I was looking to place a small bet I would sugest that the problem is likly to have been contaminated fuel and that the contamination prexisted the tsunami!

Of course only time will tell...


The plant is right by the sea, they did show some picture pre and post tsunami. I am 99% certain there was "some water ingress".

We have a standby generator at work. It was bought secondhand 40 years ago. When it was installed its tank was filled up. It's not been used for a good five years. We needed it about 10 days ago and she fired right up with 40 year old fuel


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PostPosted: Sat Mar 19, 2011 18:37 
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If they were running when flooded, then they would have been seriously damaged.
If they were started with water in the air intakes, ditto.
Engines do not seem to like encountering incompressible fluid in the cylinders. Water lock.

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PostPosted: Sat Mar 19, 2011 21:11 
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Dusty wrote:
Sadly my own experiance of back up generators is that they tend to be ignored until they are really needed!


My experience is they are tested under a full load for several hours every month.


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PostPosted: Sun Mar 20, 2011 00:44 
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Yep my (small) experience is that many companies and most certainly Councils and MOD etc run their genny's every month for an appointed suitable time to ensure operation when required.
I run my one too from time to time, to ensure it will work, when I need it, plus keep the batteries part used & charged too.

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