Wednesday, June 27, 2012

#Fukushima I Nuke Plant Reactor 1 Torus Room: Over 10 Sieverts/Hr on Water Surface

TEPCO, soon to be "effectively" nationalized, sent own workers to the Reactor 1 building at Fukushima I Nuclear Power Plant on June 26 to measure the water level, radiation levels and temperatures inside the Torus Room. The workers used the CCD camera fitted with thermometer and dosimeter, and fed the cable through the gap in the floor from the 1st floor of the reactor building.

Right near the surface of the water, it was 10,300 millisieverts/hour, or 10.3 sieverts/hour.

TEPCO reports that the dosimeter failed in the water, at it exhibited the values of "10^8 - 10^9" (100,000,000 to 1,000,000,000) millisieverts/hour.

If you recall, this was the reactor building where the steam measuring 4 sieverts/hour was gushing through the gap between the pipe and the floor on the first floor.

From TEPCO's Photos and Videos Library, June 27, 2012 (there is also a 40-minute video, I'll post here later):

TEPCO also reports on page 4 of the handout,

  • The accumulated water level was OP. 4,000. (The Torus Room floor is at OP. -1,230, so the water is 5,230 millimeters (5.23 meters) deep.)

  • Transparency of the water confirmed at least to 60 centimeters.

  • Floating sediment on the bottom.

And no, they didn't do the water sampling.

There is no information on the document about the radiation exposure of the workers. They were in the vicinity of extremely high radiation for at least 40 minutes (length of the video). I hope several groups of workers took rapid turns.


Unknown said...

Is it physically possible to have such a high radiation level (1000 or 10,000sv/h or higher) ?
What could produce extremely high radiation level ? Can plutonium or other material produce that ?
I'm quite skeptical of the readings and the tepco "it failed" usual answer to unexpected events...

arevamirpal::laprimavera said...

I don't think it is physically possible to measure such high levels, particularly 10,000 sieverts/hour levels. TEPCO says the dosimeter broke, although I've already seen some English sites that cite this outrageous number, insinuating that these were the actual measurements.

I remember seeing a tweet by the Fukushima I worker who tweets from the plant, and he said the dosimeter that they use to measure the radiation inside the Reactor Pressure Vessel can measure something like 500 sieverts/hour. Any nuclear engineers care to comment?

Anonymous said...

be aware, the dosimeter is calibarated in mSV, so it's reading 10 SV/Hr which is 10% the radiation levels of the corium in the chernobyl elphants foot

now it broke when it went to 1 Billion mSV, which is enough radiation to burn as hot as the sun, so i suspect some hot piece of floating corium burned the cable.

Anonymous said...

According to this site, the "elephant's foot" is/was 10000 roentgens/hr, or about 1000 sieverts. So at 10 sieverts, the torus room of unit 1 would be about 1% of the elephant's foot.

Anonymous said...

Regional Nuclear War and the Environment
By Eben Harrell Thursday, Jan. 22, 2009,8599,1873164,00.html

* * * * *

Climatic Consequences of Nuclear Conflict

Anonymous said...

I'd like to see a chemical sample of that goo, but at 10 Sv/h that's not very likely.

Atomfritz said...

Again a nice horror video from Tepcotainments, Inc :)

I am particularly curious what these lava-ish yellowish-brownish structures in the middle of the video are.
They look as if they dropped there like candle wax or the like.
I really hope it is not corium, but what else could it be?

Afaik, the dosimeter(s) in the RPVs only serve the purpose of indicating how much the radiation has decayed (after shutting down).
This is used to verify that the short-lived fission products have decayed sufficiently so the reactor can safely be opened for maintenance.
In operation the radiation in the reactor is measured indirectly through the neutron flux meters, as the integrated dosimeter is off-range at the many many thousand sieverts then.

Anonymous said...

probably in reference to TEPCO Chairman saying all workers may die

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