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 Post subject: Fukushima No1 Problems
PostPosted: Mar 12, 2011 4:07 am 
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Does anyone have any informed even-handed comments on the current problems at Fukushima No1.

Hopefully something better than this.

http://www.heraldsun.com.au/news/special-reports/japan-declares-nuclear-emergency-following-huge-earthquake/story-fn7zkbgs-1226020058265


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PostPosted: Mar 12, 2011 7:12 am 
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Posts: 491
Location: Columbia, SC
Latest update Tokyo Electric Power:

Quote:
Unit 1 (shut down at 2:48PM on March 11th)
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- At 8:19am, there was an alarm indicating that one of the control rods
was not properly inserted, however, at 10:43am the alarm was automatically
called off. Other control rods have been confirmed that they are fully
inserted (reactor is in subcritical status).
- Status of main steam isolation valve: closed
- Injection of water into the reactor had been done by the Reactor Core
Isolation Cooling System, but at 3:48AM, injection by Make-up Water
Condensate System begun.
- At 6:08PM, we announced the increase in reactor containment vessel
pressure, assumed to be due to leakage of reactor coolant. However, we
do not believe there is leakage of reactor coolant in the containment
vessel at this moment.
- At 5:22AM, the temperature of the suppression chamber exceeded 100
degrees. As the reactor pressure suppression function was lost, at 5:22AM,
it was determined that a specific incident stipulated in article 15,
clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
the reactor containment vessel (partial discharge of air containing
radioactive materials) in order to fully secure safety. This preparation
work commenced at around 9:43am.

Unit 2 (shut down at 2:48PM on March 11th)
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- Control rods are fully inserted (reactor is in subcritical status).
- Status of main steam isolation valve: closed
- Injection of water into the reactor had been done by the Reactor Core
Isolation Cooling System, but at 4:50AM, injection by Make-up Water
Condensate System begun.
- We do not believe there is leakage of reactor coolant in the containment
vessel.
- At 5:22AM, the temperature of the suppression chamber exceeded 100
degrees. As the reactor pressure suppression function was lost, at 5:22AM,
it was determined that a specific incident stipulated in article 15,
clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
the reactor containment vessel (partial discharge of air containing
radioactive materials) in order to fully secure safety. This preparation
work commenced at around 10:33AM and completed at 10:58AM.

Unit 3 (shut down at 2:48PM on March 11th)
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- Control rods are fully inserted (reactor is in subcritical status)
- Status of main steam isolation valve: closed
- Reactor Core Isolation Cooling System is turned off. Currently,
injection of water into the reactor is done by Make-up Water Condensate
System.
- We do not believe there is leakage of reactor coolant in the containment
vessel.
- We decided to prepare implementing measures to reduce the pressure of
the reactor containment vessel (partial discharge of air containing
radioactive materials) in order to fully secure safety. This preparation
work commenced at around 12:08PM and completed at 12:13AM.
- At 12:15PM, the reactor achieved cold shut down.

Unit 4 (shut down at 2:48PM on March 11th)
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- Control rods are fully inserted (reactor is in subcritical status)
- Status of main steam isolation valve: closed
- Reactor Core Isolation Cooling System is turned off. Currently,
injection of water into the reactor is done by Make-up Water Condensate
System.
- We do not believe there is leakage of reactor coolant in the containment
vessel.
- In order to cool down the reactor, injection of water into the reactor
had been done by the Reactor Core Isolation Cooling System, however, At
6:07AM, the temperature of the suppression chamber exceeded 100 degrees.
As the reactor pressure suppression function was lost, at 6:07AM, it was
determined that a specific incident stipulated in article 15, clause 1 has
occurred.
- We decided to prepare implementing measures to reduce the pressure of
the reactor containment vessel (partial discharge of air containing
radioactive materials) in order to fully secure safety. This preparation
work commenced at around 11:44AM and completed at 11:52AM.

Indication from monitoring posts installed at the site boundary did not
show any difference from ordinary level.
No radiation impact to the external environment has been confirmed. We
will continue to monitor in detail the possibility of radioactive material
being discharged from exhaust stack or discharge canal.
There is no missing person within the power station.
We are presently checking on the site situation of each plant while
keeping the situation of aftershock and Tsunami in mind.
A seriously injured worker is still trapped in the crane operating console
of the exhaust stack and his breathing and pulse cannot be confirmed.
Currently, the rescue efforts are under way.
A worker was lightly injured spraining his left ankle and cutting both
knees when he fell while walking at the site. After medical treatment
and subsequent rest, the worker has got back his workplace.


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PostPosted: Mar 12, 2011 8:57 am 
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Joined: Aug 29, 2008 4:55 pm
Posts: 496
Location: Idaho Falls, Idaho
so what is the video of? Water hitting the electrical switchgear?


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PostPosted: Mar 12, 2011 9:13 am 
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Joined: Apr 24, 2008 4:54 am
Posts: 491
Location: Columbia, SC
I wold have to flat out guess. If I had to I would say H2 from the main generator cooling system, leak then explosion.


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PostPosted: Mar 12, 2011 9:13 am 
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Joined: Dec 03, 2008 5:23 pm
Posts: 137
Location: Oak Ridge, TN
Ida-Russkie wrote:
so what is the video of? Water hitting the electrical switchgear?

From the various news articles, it appears to have been an explosion that destroyed the reactor building (external building protecting the primary containment). The primary containment is intact.

http://hosted.ap.org/dynamic/stories/A/ ... 2-03-29-13

This reactor has a Mark I containment (as shown below) and it appears that the outer reactor building was what was destroyed. Not the primary containment.

Image


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PostPosted: Mar 12, 2011 9:44 am 
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Joined: Jul 14, 2008 3:12 pm
Posts: 5058
Looking at the videos it is evidently an almost invisible cloud which combusts and the detonation causes a shockwave. Most plausible is indeed H2, it has every sign of that. However I don't understand where the H2 comes from. If the primary containment is intact then then it can't be the top fuel rods, unless they have some sort of filtered stack to protect against overpressurization of the primary containment, but that doesn't make sense to me. If the hydrogen would come from generators or other electrical equipment shat short-circuits due to deluge, then that explains the situation much better. 40 year old outside building, 8+ Richter scale quake, yeah its easy to see how an explosion could destroy such a weakened building. Nuclear grade steel and alloys should be a lot less bothered by earthquakes.

So far still 0 deaths due to nuclear plants. Several injured and one worker received ~10 rem, a guy with a broken leg and one with a broken nose apparently (did they fell off their feet by the earthquake?). Still no deaths.

Now why is the media not reporting much about the fossil fuel deaths? One source speculates about 100 dead from oil refinery explosions. Major refinery and gas fires have occured and I would like to know more about those. Stupid biased media. Japan is struck by a 1600 plus death toll natural disaster and half of the media coverage is engaging in hyperbole about a 0 death toll nuclear industry. Representativeness is apparently not a value for many journalists.


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PostPosted: Mar 12, 2011 9:52 am 
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Joined: May 31, 2009 11:15 am
Posts: 47
Location: Columbus, OH
I am a little confused here...

The size of the explosion (assuming H2), would seem to indicate that the fuel rods are at least partially uncovered resulting in them being hot enough to dissociate water.

This doesn't appear to jive with the new releases though.

Either way, there is the normal disproportionate media frenzy around the status of the Nuclear plants considering the regional devastation...


Edit:

http://www.reuters.com/article/2011/03/ ... ews&rpc=43

Looks like they are going to use seawater for cooling next. They appear to confirm the H2 explosion and the reactor vessel remaining intact as well.

Wiki is staying updated pretty well:

http://en.wikipedia.org/wiki/Fukushima_ ... ower_Plant


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PostPosted: Mar 12, 2011 10:02 am 
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Joined: Dec 03, 2008 5:23 pm
Posts: 137
Location: Oak Ridge, TN
I don't know what caused the explosion, there are conflicting stories on this. Will have to wait for more information.

I agree that there is a disproportionate amount of attention on this right now given the large loss of life and destruction from the tsunami itself. Rod Adams has a good write-up on his blog that puts this in perspective:

http://atomicinsights.blogspot.com/


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PostPosted: Mar 12, 2011 10:10 am 
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Pretty good video overview of the situation here:

http://www.bbc.co.uk/news/world-middle-east-12307698


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PostPosted: Mar 12, 2011 10:12 am 
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Isn't this the same design as Vermont Yankee?


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PostPosted: Mar 12, 2011 10:14 am 
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robert.hargraves wrote:
Isn't this the same design as Vermont Yankee?


I was wondering the same thing...

It appears to be a BWR3 design...not sure about Yankee...


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PostPosted: Mar 12, 2011 10:14 am 
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Yes we have to determine the source of the H2. There are at least two options:

1. Electrical non-nuclear equipment short circuited after flooding with water, resulting in very high temperatures, dissociating hydrogen and oxygen. Results in explosion.
2. The top fuel elements, lacking coolant were too dry and became hot enough for hydrogen reactions. Resulting overpressure from the primary containment vented by stack (they have one right?) which caused it to escapte to outside air which is of course not inerted (lots of oxygen). Results in explosion.

The experts and authorities seem to indicate the former, some popular media indicate the latter, however tepco did suggest that the top fuel elements were insufficiently cooled. Either way it looks like a total loss economically and an expensive cleanup will no doubt follow, but nothing serious yet in terms of public safety.

From Reuters:

Quote:
Reuters – Reactor core intact – No repeat of Chernobyl disaster for Japan-experts 2011 03 12 | 1411 GMT

* Experts discount threat of “Japanese Chernobyl”
* Better design key to safety concerns

BRUSSELS, March 12 (Reuters) – Japan should not expect a repeat of the Chernobyl nuclear disaster after an explosion blew the roof off one of its nuclear power plants that had been shaken in a huge earthquake, experts said on Saturday.

Japan’s Daiichi 1 reactor north of the capital Tokyo began leaking radiation after the 8.9-magnitude earthquake triggered a tsunami, and swiftly prompted fears of a nuclear meltdown.

But experts said pictures of mist above the plant suggested only small amounts of radiation had been expelled as part of measures to ensure its stability, far from the radioactive clouds that Chernobyl spewed out when it exploded in 1986.

“The explosion at No. 1 generating set of the Fukushima nuclear plant in Japan, which took place today, will not be a repetition of the Chernobyl nuclear disaster,” said Valeriy Hlyhalo, deputy director of the Chernobyl nuclear safety centre.

“Apart from that, these reactors are designed to work at a high seismicity zone, although what has happened is beyond the impact the plants were designed to withstand,” Hlyhalo said.

“Therefore, the consequences should not be as serious as after the Chernobyl nuclear disaster.”

Japanese officials said on Saturday that the nuclear reactor’s core was intact, and that sea water would be poured into the leaking reactor to cool it down and reduce pressure in the unit — a statement that should calm any fears.

Experts said it was crucial to make sure the steel reactor container had not been shattered in the explosion or in the earthquake.

Robert Grimes, professor of materials physics at Imperial College London, said earlier it had seemed that back-up generators had failed and had allowed pressure to build up.

“It does seem as if the back-up generators although they started initially to work, then failed,” Grimes told BBC television, adding that the explosion was probably the large release of that pressure.

“If it’s that, then we’re not in such bad circumstances … Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained.

Most experts said the relatively slight damage to the reactor was testimony to the improved security of nuclear power, something that has convinced more governments to adopt the technology in recent years despite environmentalists’ concerns.

“We must remember that there are 55 reactors in Japan and this was a huge earthquake, and as a test of the resilience and robustness of nuclear plants it seems they have withstood the effects very well,” Regan said.


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PostPosted: Mar 12, 2011 10:25 am 
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Here are the other "sister" plants to Fukushima 1:

GE2 (BWR3)
Dresden 2 USA 850 MWe
Dresden 3 USA 850 MWe
Fukushima Daiichi 1 Japan 460 MWe
Garona Spain 450 MWe
Millstone 1 USA 650 MWe
Monticello USA 550 MWe
Pilgrim 1 USA 650 MWe
Quad Cities 1 USA 850 MWe
Quad Cities 2 USA 850 MWe


Per this link:

http://www.isoe-network.net/index.php?o ... Itemid=125


VY is noted as a BWR4


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PostPosted: Mar 12, 2011 10:26 am 
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Location: Columbia, SC
Simpler would be Main Generator (many are cooled internally by H2 gas) gas leaks into enclosed spaces leading to an explosion.

But there is simply not enough information to even speculate with any degree of accuracy. We just don't know enough. And the talking heads stating speculation as fact just annoy the crap out of me.


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PostPosted: Mar 12, 2011 10:31 am 
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Location: Oak Ridge, TN
It appears that Fukushima Daiichi 1 is a BWR 3 while Vermont Yankee is a BWR 4. This presentation has some information on an overview of BWR technology and differences between the BWR types:

http://www.edf.com/fichiers/fckeditor/C ... ics_va.pdf


Monticello is a BWR 3. BWR 3s and 4s are very similar and VY has the same type of containment as Fukushima 1.


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