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Are there any nuclear power plants on oceanic coastlines like Fukashima?

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Hiddencamper
#19
Jan28-13, 06:25 AM
P: 178
Quote Quote by Kutt View Post
So if the spent fuel pool in reactor #4 did not boil dry and the core was fully off-loaded to the SPF for maintenance purposes, why was there a fire and explosion in that particular unit? The reactor was de-fueled and completely empty.

Here is a photo of the badly damaged and burned building for reactor 4. Obviously there was a fire and an explosion.

The standby gas treatment systems from unit 3 and unit 4 exhaust to the same common stack vent.

When the power failed, as is typical for BWR plants, the standby gas treatment system is automatically lined up to provide containment vacuum. Remember there was just under an hour between AC power failure and tsunami inundating the plant. The SGBT system dampers from Fukushima fails "As Is" (based on the last time I saw drawings/reports on it). As a result, when the unit 3 containment was vented finally, hydrogen escaped to the unit 3 secondary containment, through the SGBT filters (the open vent path), and some of that escaped into unit 4, where it concentrated enough to cause an explosion.

Unit 3 had a very large explosion. There was a LOT of hydrogen generated. With that much hydrogen, its very feasible for an amount of it to migrate to unit 4. Remember that hydrogen only requires 4% concentration in atmosphere to be explosive. Also the SGBT system itself is situated in Mark I reactors about 2/3rds of the way up inside the secondary containment (reactor building)

There are plenty of TEPCO reports on this as well as an analysis which shows that enough hydrogen was generated, and the necessary lineup was established, to allow hydrogen to migrate. Analysis also showed that the spent fuel pool of unit 4 had a couple days prior to full boil down, and the fuel/clad reaction in fuel only occurs above something like 1700 degrees F (not positive on exact number, but 1700 is when fuel embrittlement starts occurring), which cannot physically happen with water around the fuel, as the boiling effect would limit the fuel cladding temperatures to a few hundred degrees

Honestly though, I'm going off of memory on a lot of this. read the hydrogen section for unit 4 here: http://icanps.go.jp/eng/03IIfinal.pdf

seriously you should read the report i linked. it's got all the technical details in relatively plain english (compared to most nuclear industry reports) and will likely answer your questions
a.ua.
#20
Jan29-13, 02:26 AM
P: 119
nikkkom
hydrogen was vented from Unit 3 and due to a faulty design of the common vent stack, part of it ended up entering Unit 4 and later exploding there.
Why the explosion at unit № 4 was not like an explosion unit № 1 ?.
Hydrogen would go up, because after the destruction of the ventilation pipe passed day.
Maybe there was another way for passage of hydrogen.
Common adverse communication with underground block № 3 ?

Besides a lot of secrets in connection with the actions of the U.S. army to extinguish the fire at unit 4.
Maybe it is, they opened the gate between the exposure and swimming pool reactor.?


At 7 am, a situation arose which the US military is still keeping quiet about.
http://ajw.asahi.com/article/0311dis...AJ201301280006
Hiddencamper
#21
Jan29-13, 06:28 AM
P: 178
Quote Quote by a.ua. View Post
nikkkom

Why the explosion at unit № 4 was not like an explosion unit № 1 ?.
Hydrogen would go up, because after the destruction of the ventilation pipe passed day.
Maybe there was another way for passage of hydrogen.
Common adverse communication with underground block № 3 ?

Besides a lot of secrets in connection with the actions of the U.S. army to extinguish the fire at unit 4.
Maybe it is, they opened the gate between the exposure and swimming pool reactor.?
The standby gas treatment line IS the common line between units 3 and 4. Read the linked information, it clearly explains what they found, all the possibilities, and why this is the most probable cause. The hydrogen, as it left the high pressure containment in unit 3, would have travelled out through the standby gas treatment line, where it would have been divided between the stack and the unit 4 reactor building, similar to how voltage is divided among two loops of different resistance.

The us army was not putting a fire out because no fire occurred. Additionally it doesn't matter if the refueling gates were in place or not as the reactor core is empty in unit 4 (additionally that doesn't even make sense, there's no interaction between the core and pool that would cause fire)

You need to understand with hydrogen, once you pass the LEL (lower explosive limit) all it takes is a little spark to set it off. A relay chattering, a hot glow plug, a lightbulb flickering.

Also this is a place for science engineering and physics. Let's please keep the conspiracy theories to a minimum. There is a lot of good compiled information in the various Fukushima posts, there is also a lot of official source information that is backed up by measurements, readings, and physics.
a.ua.
#22
Jan29-13, 08:31 AM
P: 119
Hiddencamper
Additionally it doesn't matter if the refueling gates were in place or not as the reactor core is empty in unit 4 (additionally that doesn't even make sense, there's no interaction between the core and pool that would cause fire)
Reactor № 4 is in the scheduled maintenance and was full of water.
Gates connecting the fuel pool and the reactor were damaged and some of the water from the reactor flowed into a swimming pool. (This information is from the Japanese)
If not for that, the water in the pool would not be enough.
According to U.S. estimates, it would not have to boil, it would have heated up to 90 degrees Celsius and evaporated.

Let's please keep the conspiracy theories to a minimum.
I'd love to, but the Japanese have repeatedly concealed information.
Also, I have never seen photos kontaymenta 4 reactor inside.
Gateways do not even photographed.
Hiddencamper
#23
Jan29-13, 09:02 AM
P: 178
Quote Quote by a.ua. View Post
Hiddencamper


Reactor № 4 is in the scheduled maintenance and was full of water.
Gates connecting the fuel pool and the reactor were damaged and some of the water from the reactor flowed into a swimming pool. (This information is from the Japanese)
If not for that, the water in the pool would not be enough.
According to U.S. estimates, it would not have to boil, it would have heated up to 90 degrees Celsius and evaporated.



I'd love to, but the Japanese have repeatedly concealed information.
Also, I have never seen photos kontaymenta 4 reactor inside.
Gateways do not even photographed.
I think you are misunderstanding the reports of the unit 4 SFP.

The reactor cavity and fuel pool were fully flooded with the gates installed. The gates were leaking, but this is of no direct concern as the water levels are the same. The concern that a us engineer identified is if the reactor cavity bellows collapsed somehow due to a future earthquake, water COULD drain out of the pool. However due to the weir walls designed into the fuel pool, the lowest the water could drop was a couple feet over the fuel. This reduces time to boil, but does not present a radiological issue.

The 90 degrees C was from a calculation to find maximum pool temperature using conservative assumption (no evaporation, Adiabatic heatup). The pool likely was below 90 C by the time the heatup was ceased. It was still below boiling point meaning there would not have been much loss of inventory.

Stating that Japan lied and refusing to use official data means that you are intentionally trying to avoid the facts about the accident. We are trying to talk about the actual accident and it's effects. Not the conspiracy theories. There are plenty of places that support that type of talk and it might be better to go find a different forum. If you are interested in actual data and interpretation of results by actual nuclear professionals feel free to ask more questions, but I for one will not give into speculation or conspiracy.
Kutt
#24
Jan29-13, 02:29 PM
P: 236
Here is the SPF at one of the Fukashima reactors. Not sure which one..

The fuel assemblies are undamaged and you can see debris from the explosion sitting on top of them.

a.ua.
#25
Jan30-13, 02:49 AM
P: 119
Hiddencamper
Stating that Japan lied and refusing to use official data means that you are intentionally trying to avoid the facts about the accident.
Did I wrote about the lies?
Japanese company and the government simply does not report some details
Many of the findings in the report is the assumption is more or less likely.
They do not know many things about their plant.
Here is a recent example.
http://ex-skf.blogspot.com/2013/01/f...ipes-that.html

That's ridiculous, and besides, they "cast a shadow"
it is a shame for the entire nuclear industry.
Astronuc
#26
Jan30-13, 06:54 AM
Admin
Astronuc's Avatar
P: 21,806
Closed for moderation. The discussion has drifted off-topic to rehash the Fukushima event rather than security of other NPPs sited along coastlines.

The spent fuel pool in Unit 4 did not go dry, nor was the fuel severely damaged, as was determined from visual examination and water sampling.
http://info.ornl.gov/sites/publicati...s/Pub33574.pdf

Industry responses to NRC concerns about plant safety following Fukushima event:
http://www.nrc.gov/reactors/operatin...an-plants.html


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