Photos showed debris from the reactor building explosion up to about 30 meters inside of the building.
Radiation levels measured 150 mSv/hr on the building’s second floor, but dropped dramatically on the third and fourth floors. The radiation dose levels on the fifth floor (operating floor) were measured at 53.6 mSv/hr 1 meter from the floor. TEPCO is unsure of the cause of the higher radiation levels on the second floor.
Since the workers were able to use the balloon, they did not utilize the four-propeller flying robot that had also been shown in press releases.
Source: JiJi Press