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.