The water level turned out to be lower then 4.000m at the most.
Even the radiation resistant endoscope for 1000Sv got too much noise.
Tepco inserted 2m of the endoscope to reactor2 from the hole called X53 on 1/19/2012. The operation took 6 Tepco employees and 28 workers from subcontract companies. The maximum dose of the worker was 3.07 mSv.
As the result, they could not see the water surface. Because the radiation level was too high, endoscope had too much noise to capture the clear image.
The heat gauge on the endoscope measured 44.7℃ at 9:13. The heat gauge set inside of around X53 measured 42.6℃, so Tepco judged the heat gauges inside are not completely broken.
Unexpectedly, inside was not too steamy but because the evaporated water kept dropping inside, it also prevented the camera from capturing clear image.
The coating inside of the reactor was damaged and ripped off like squama.
From the gap of the pressure between inside of the reactor and suppression chamber, Tepco assumed the water level could be above the grating cover, but they could not see the water at least above the cover.
The height of the cover is around 4.0m from the bottom of the reactor. At least the water level is lower than there.
Actual Fukushima worker analyzes the main problem is the extremely high level of radiation.
I’m back Today was warm, didn’t feel icy in my hands and feet. We managed to see inside of the PCV of reactor2. The image was clearer than I thought. I thought the inside might be more steamy. That’s sad not to be able to see the water surface, but it was an improvement for sure. but I’m concerned about the radiation level.
The camera we used today can resist for 1000Sv, but even the camera got so much noise (the white spots), the radiation level is really high. At usual reactor test, we put water-resistant camera into the reactor but it gets too much noise when the camera goes close to the highly radioactive place called top guide.
If you put the camera at too radioactive place for too long, the camera gets broken. Today the endoscope became like that. To get more detailed image, we would need a more protective camera. It would cost 100 million yen to buy the camera what can get close to the fuel debris with color image.
For the next time, we need to develop new equipment. We shall use the same hole to measure the radiation level next time. We can’t even tell what to do if we don’t know the radiation level inside.