Friday, June 10, 2011

#Fukushima I Nuke Plant Reactor 3 Bldg Radiation Measurement

as released by TEPCO at the press conference on June 10.

9 workers (5 TEPCO employees, 4 from TEPCO affiliate companies) entered the reactor building to do measurements and inspections in order to prepare for the nitrogen injection into the Containment Vessel. They spent about 30 minutes, surveying about half the floor, getting exposed to 5.88 to 7.98 millisieverts of radiation for their work.

96 millisieverts/hour radiation at the staircase going down to the basement, at the southwest corner (circled in red).

Blowup of the photo at the location (3), where 100 millisieverts/hour radiation was measured:


Ono said...

This area is just under the spent fuel pool.
There must be something.

Atomfritz said...

When looking at both pictures of location #3, my first impression was that of looking into a condemned house.

Radiation distribution suggests that the black stuff (soot) seems to have originated from above, like if heat and smoke of a blaze upstairs torched down.
Sadly the photos are of such low detail that I cannot recognize much.
This assumption could be supported by observing that nearby locations 1 and 2 look comparatively clean. Maybe the containment breached on a higher floor at some penetration and/or the dirt was released through a a containment hatch which popped open due to the blast. I mean, it was definitely locked when the reactor got shut down after the earthquake. Making a massive tresor door's locks break and swing the door open indicates quite some explosive power from the inside.
However, the radiation inside the building and near the containment hatch are comparatively low, and so I guess that the main release path was via the concrete reactor plugs at the top floor. If I guessed correctly the equipment hatch (and possibly other penetrations, too) popped open when the pressure spike already subsided. If they would have opened earlier, a much larger part of the releases would have gone through the floors of RB #3, rendering it much more radioactive.

By the way, I find it very interesting that Tepco reduced the overpressure in reactor 3 from 0.28 to 0.25 kPa. This avoids much gas escaping through the equipment hatch and the other perforations, and thus helps slow down the inevitable constant rise of radiation in RB#3.

Atomfritz said...

oops, posted the comment in a wrong topic.
Correct topic is here:

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