Japan Earthquake: nuclear plants

havemercy

Sorry, but they are discussing the temperature of the pool and not of the reactor no ?

the drop of the temperature of the spent fuell pool, i guess, could not lead to the conclusion that the core is gone undergroud, isn't it ?

TCups

I will "guess" here, but it will be an educated guess. If the survey were done by a helicopter, then they might be using a laser interferometer and it would indeed measure the surface temperature of what it were shined on, in this case, the surface of the exposed SFP of unit 3. This would say nothing about 1) how deep the water is in the pool, or 2) if there were still fuel rods in the pool, or if there were still fuel rods in the pool, how many were still there. Also, Fred's "news fragment" doesn't indicate degrees in Fahrenheit or Celsius. I would hazard to "guess" degrees Celcius (ºC).

If they are all still there, then a temp reading of 23ºC is fantastic news. If all of the fissionable material has been blown out of the pool and (speculating wildly here) lies out and about on the ground or atop the building ruins, "beaming" neutrons and scattering gamma radiation, then there would be no reason for the pool to heat up. The real answer could be either or anything between those two ends of the possibility spectrum. Who knows.

KateB

Here is what I had asked earlier re: the Neutron ray, as well as a person's excerpt of the press item describing said neutron ray- that also inquired above me (page 58 near the bottom) My knowledge of nuclear physics is rudimentary, but wouldn't neutron rays captured 1.5 km away, even such low readings, lead one to extrapolate that fissable material escaped the Suppression pools, and perhaps even containment?

From Reuters: "Radiation at the crippled Fukushima No.2 nuclear reactor was recorded at the highest level since the start of the crisis, Japan's nuclear safety agency said on Wednesday. An agency spokesman said 500 millisieverts per hour of radiation was measured at the No.2 unit on Wednesday. Engineers have been trying to fix the plant's cooling system after restoring lighting on Tuesday."

from Kyodo:

Electric Power Co. said Wednesday it has observed a neutron beam, a kind of radioactive ray, 13 times on the premises of the Fukushima Daiichi nuclear plant after it was crippled by the massive March 11 quake-tsunami disaster.

TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant's No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level.

Not trying to flame the fire here. The rad levels are low and I'm hoping TEPCO continues to make progress controling the site but the neutron beam got me thinking about reactor integrity. Neutron beams are product of fission correct? Would this finding confirm reactor damage even if it's just a pin hole?

Y, 11:28 AM #928
KateB

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Re: Japan Earthquake: nuclear plants
I was actually just going to query on the neutron beam reported 1.5 km from the Fukushima nuclear plant. As a Biochem undergrad, my knowledge of physics is rudimentary at best, but wouldn't a neutron beam offsite signify release of plutonium/uranium, and to extrapolate further, does this mean that one of the spent fuel pools blew fissable material "sky-high"? What are the implications of this news? I have been following this thread for a while, and this has been a great pool of knowledge and learning for me.

|Fred

I thought that emphasized strongly enough my surprise , rather than my joy.

Tepco had this information since this morning... and it was only released at 21:15
it is 2:45 am ... and we are still waiting for tepco press conference that has been delayed ... ( am I losing my science? )

NB: Japanese do not use barbaric units.. they use celcius :o)
Ps: They says that the temperature mesured on the 23th was 57°

TCups

No, Fred -- keep us informed. Thanks.

Pheesh

At the bottom of this article from today..

http://english.kyodonews.jp/news/2011/03/80849.html

"The government said, meanwhile, it detected 2.54 million becquerels of iodine and 2.65 million becquerels of cesium, another radioactive substance, from weed leaves in the village of Iitate in Fukushima Prefecture about 40 km northwest from the nuclear plant, far above the provisional limits for food of 2,000 becquerels for iodine and 500 becquerels for cesium.

Abnormally high levels of these materials were also detected again in the sea near the plant, TEPCO said, warning the radiation levels in seawater may keep rising."

So...evac zone is 20km...these levels were detected 40km away, yet they are only 'considering' increasing the evac zone for convenience. Am I just misunderstanding the amounts quoted, they seem significant.

Thanks everyone for the information here, I have been quietly absorbing it.

AntonL

the turbine building 3 is about 125 x 35 metres
the reactor building 3 is about 45 x 34 metres
reactor building to turbine building is about 25 metres apart
(source measured on google earth 35:25:15N 141:02:02E)

Turbine building has an aspect ratio of 3:1


Japanese plan has an aspect ratio of 2:1
I estimate it at 120 by 60 metres (based on door sizes, corridors)
Has no doors to the outside, so it is either a basement or an upper floor,
My guess upper floor as a ladies and gents can be identified. (just above the ng of Turbine Building)

My next guess - upperfloor of turbine building + connecting building between reactor and turbine

Attached Thumbnails

 

Bodge

Hi guys, 1st post!

Fascinating, terrifying stuff in this thread..

Here is a report by the US Department of Energy on blackout (no power supply) conditions in a Mark.1 G.E. BWR.

Note the timeline below:




Here is the full report.

http://www.osti.gov/bridge/servlets/...5j/6124656.pdf

It states that all reactors should have ruptured their boilers within 8 hours.

Can we *really* have corium below ground? Where is the water table?

Joe Neubarth

So all the diesel generators were on the ground floor? I have read that the diesel generators were washed away. So what was the extent of the damage to the main Turbine Generator? I am guessing that is what was in the middle of the schematic???

Borek

They were not. They started to work as expected and failed after about an hour.

|Fred

tepco conference just finished at 5 am !!... ****

Borek

If memory serves me well, cooling systems were working for about 9 hours - first on DG, then on batteries. I don't know how fast heat output from decay goes down, but for sure it is the strongest during first hours after scramming.

Bodge

Thanks Borek



Still worrisome though

|Fred

Japanese are considering upgrading to INES 6, very confusing they were talking about radiation in terms of 27 Ci in the water on the power plant.
I'll wait for the official bulletin..

edit: mainly the press conference was minor statement from tepco indicating that, the worker went to a zone that was supose to have minor "air" radiation,when they arrived they found 13 cm of water , 2 of them where not prepare for that and did not have boots, (those 13 cm of water were not present the day before)
the radiation was in the range of 400mSv/h .
The press asked a lot of questions as for where does the watter come from etc.. Tepco does not know , one hypothesis that they are considering is a total meltdown of the rods (Spent Fuel ?) ..

we will get a better view tomorrow

M. Bachmeier

From post #22 http://www.physicsforums.com/showthread.php?t=481620

Re: Astronuc

"The matter of the neutron 'beam' or neutron radiation is of concern. It would seem to indicate loss of transuranics (fuel particles/fines) from the containment, which is not a good sign.
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KateB

Thank you. That is what I was concerned about. I appreciate the reply, It didn't occur to me to check other threads. I know speculation is not encouraged here, but perhaps someone could posit an educated guess as to the implications of transuranics escaping containment, and most especially if they had come from the Hydrogen explosion at No. 3 that rendered the building? I realize this hinders the effort at containment, but my question centers more on what the best and worst outcome regarding the possible escape of these particles could mean, mostly in the long term, as I know the half lives of these isotopes can range from multiple thousand to billions of years. I remember hearing a scientist say that the "fallout" from an atomic bomb was "safer" (which I realize is a ludicrous word to use in any discussion on large radioactive releases and/or bombs) than the slow fission and continued presence of transuranics within the environment. Is there a plausible way to recover any of these materials from the environment, IF there is indeed any release, or will an extended area have to be abandoned for...an eternity in human foresight? Thanks in advance.

Bodge

Anything to report?