Japan Earthquake: nuclear plants

M. Bachmeier

Quote by AntonL

Hmmm, we have not seen any photos in possession of US government of todays surveillance flight by drone, which USA have passed to Japan. I just read that USA will reimburse 20000 US citizens their flight home Hmmm they seem to know more than they willing to tell

Seems there's no indication at present that photos will be released for public scrutiny.

Astronuc

Quote by TCups

It looked like on the earlier schematic that the fuel-handling machine only went over the core or the pool, not on both sides of the pool. That said, it also looked as if there might be a second pool on the opposite side. Not a detailed enough drawing for me to know. What is encouraging is the apparent integrity of the concrete walls beneath the fuel-handling machine. Is is a safe assumption that the rising smoke is coming from the pool and fuel rods? I think probably so.

Is the overhead crane (2) that is orange perhaps a completely different structure than the yellow fuel-handling machine under it? The overhead crane rails do traverse the entire length of the building. The fuel-handling machine's tracks on the floor only go as far as the access to the core. And there does look to be a second pool of some sort on both sides of the core containment (3), (4).

The overhead crane is used to lift the heavy plug and upper equipment of the top of the reactor pressure vessel (RPV). The plug can be set aside on the floor (I'm not entirely familiar with specific practices). The RPV head and internals, e.g., steam dryers, would be placed in an equipment pool (4) for shielding.

The refueling machine handles the fuel between the SFP (3) and core. There should be a transfer canal between the reactor cavity and SFP. When the core is being unloaded or loaded, the irradiated fuel is transfered underwater which shields the workers from the radiation.

Some wonder if the any of the SFPs or the transfer canal area, particualy in Unit 4, were damaged by the quakes. If so, there could be a leak - which compounds the problem of water loss from the SFP. BUT - we don't have that information.

1001001

What is the volume of SFP's in Daiichi reactors 3 and 4?

rjb100

Does anyone understand why the Grid supply from the Japanese nuclear plants cannot be simply back fed to supply electricity to the cooling pumps.

Relying on diesel generators at all nuclear plants seems a little hit and miss.

andyr

Quote by rjb100

Does anyone understand why the Grid supply from the Japanese nuclear plants cannot be simply back fed to supply electricity to the cooling pumps.

Relying on diesel generators at all nuclear plants seems a little hit and miss.

You mean from other plants that were unaffected? Or you mean from the Fukushima plant?

Astronuc

Quote by rjb100

Does anyone understand why the Grid supply from the Japanese nuclear plants cannot be simply back fed to supply electricity to the cooling pumps.

It appears that the transmission and distribution system in the area was damaged or destroyed by the quake, and parts by the tsunami. TEPCO is attempting to put in a 1 mi/1.6 km line ASAP - and I expect they have been working very hard to restore grid connection.

Relying on diesel generators at all nuclear plants seems a little hit and miss.

The EDGs are there precisely to provide power when there is loss of offsite power - loss of connection to the grid.

jinxdone

Quote by TCups

Perhaps. But as a radiologist, I make my living with my eyes, interpreting what I see. Here is a picture from the net of the Fukushima (nomen, omen?) of units 3 and 4, dated October 3, 2008. Note the location of the berm (X).

another view, after unit 3 has exploded, but before the explosion and fire at unit 4:

http://media.kansas.com/smedia/2011/...filiate.80.jpg

Some brave soul peeked out from behind that berm (X) in the first photo to take this picture (annotated with my personal interpretations).

Presuming the access tunnel (1) in the diagram below is coming from the building next to the reactor in the first photo, which seems reasonable, that square hole in the side of unit 4 is, in fact, precisely where the diagram puts the SFP's location (3).

Do you think the roof of the Unit 4 building still looks intact? If there is still (boiling?) water in the SFP, where is the steam? Instead, I see a faint cloud of dark, sooty smoke wafting from the square hole with the red dots inside at an angle across the tower to the right, in the last photo. I hope I am wrong, but my eyes tell me something different from the official reports you quote.

I looked at the helicopter video frame by frame. There are a few frames in it showing the side of reactor building 4 with the supposed SFP hole in it.

The angle is only visible for a few frames before the tower obscures the view at 00:57. The copter is moving from this location showing reactor 4 towards the bottom left and reactor buildings 3, 2 and 1 are shown in succession in this fly-by.

Curiously, I think there should have been a much better view of this side of reactor building 4 earlier in the video, as the helicopter was flying the other way. But this part of the video is missing (I would assume it has been cut out?).

See the video for yourself on youtube.

turbo

Surely, it is not necessary to rely on hand-held video taken from a helicopter trying to stay out of a dangerous or fatal radiation zone. We have a carrier group off-shore that likely has remote surveillance drones. Decent hi-rez stuff (with IR sensors as well, possibly) that could show us in great detail what is going on there without risking human exposure.

Astronuc

Worker at Japanese nuclear plant: We’re putting our lives on the line

http://news.yahoo.com/s/yblog_theloo...es-on-the-line

The sprayed water like they were fighting a fire, not filling a pool with water.

turbo

Quote by Astronuc

Worker at Japanese nuclear plant: We’re putting our lives on the line

http://news.yahoo.com/s/yblog_theloo...es-on-the-line

The sprayed water like they were fighting a fire, not filling a pool with water.

Yep. Air-dropping water from a bucket made for fighting forest fires is not too effective. To replace half of the water in a 40x40x40 SFP would require 992 tons of water, accurately delivered. Earlier reports that 30 (IIR) tons of water had been dumped from 'copters seem like a drop in the bucket, especially when looking at that image, because the water is essentially going about everywhere and is not targeted.

For fire-suppression in a brushy place, those drops might be effective, but not here.

TCups

Quote by turbo-1

Yep. Air-dropping water from a bucket made for fighting forest fires is not too effective. To replace half of the water in a 40x40x40 SFP would require 992 tons of water, accurately delivered. Earlier reports that 30 (IIR) tons of water had been dumped from 'copters seem like a drop in the bucket, especially when looking at that image, because the water is essentially going about everywhere and is not targeted.

For fire-suppression in a brushy place, those drops might be effective, but not here.

I am wondering if there isn't some place they could scoop up lots of snow and drop that. Per volume, the weight wouldn't be different. Snow would be less dense than water, but big snow ball might be easier to drop precisely on target, and the heat of transition of the ice would provide an additional 880Kcal/M of cooling as it melted to water to fill the SFP.

kfmfe04

NYT article on US fly-over:

http://www.nytimes.com/2011/03/18/wo...a/18intel.html

Astronuc

Quote by kfmfe04

NYT article on US fly-over:

http://www.nytimes.com/2011/03/18/wo...a/18intel.html

and this article has some decent pictures and schematics
http://www.nytimes.com/interactive/2...rs-status.html

Borek

Polish media reports electric line is ready.

turbo

Quote by Borek

Polish media reports electric line is ready.

NBC nightly news, too. Now, let's hope pumps, valves, etc work.

*Angry Citizen*

What I'm most curious about are the spent fuel ponds. Would the reinstatement of power in the facility allow the ponds to be cooled without having to pump in a continuous stream of fresh water? I'm just fuzzy on whether or not there's an actual cooling system for the spent fuel ponds, or if they just replace the water as it boils off.

kloptok

Does it matter for the spent fuel pools if there is external power or not? If there isn't some electrical pumping system to refill the pools it doesn't seem like it would make a difference.

Don't take me wrong, of course it's a huge improvement if external power is available, especially for the reactor cooling. But I was under the impression that the real danger now is largely due to the spent fuel in the pools.

EDIT: Noted that Angry Citizen posted simultaneously about the same question as me.

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1001001	What is the volume of SFP's in Daiichi reactors 3 and 4?

rjb100	Does anyone understand why the Grid supply from the Japanese nuclear plants cannot be simply back fed to supply electricity to the cooling pumps. Relying on diesel generators at all nuclear plants seems a little hit and miss.

turbo Recognitions: Gold Member	Surely, it is not necessary to rely on hand-held video taken from a helicopter trying to stay out of a dangerous or fatal radiation zone. We have a carrier group off-shore that likely has remote surveillance drones. Decent hi-rez stuff (with IR sensors as well, possibly) that could show us in great detail what is going on there without risking human exposure.

Astronuc Admin	Worker at Japanese nuclear plant: We’re putting our lives on the line http://news.yahoo.com/s/yblog_theloo...es-on-the-line The sprayed water like they were fighting a fire, not filling a pool with water.

kfmfe04	NYT article on US fly-over: http://www.nytimes.com/2011/03/18/wo...a/18intel.html

Angry Citizen	What I'm most curious about are the spent fuel ponds. Would the reinstatement of power in the facility allow the ponds to be cooled without having to pump in a continuous stream of fresh water? I'm just fuzzy on whether or not there's an actual cooling system for the spent fuel ponds, or if they just replace the water as it boils off.