TEPCO has released a video taken inside the Fukushima Daiichi unit 2 primary containment vessel.
The video is grainy and unclear, due to the quantity of water and radiation-induced interference, TEPCO said, although it did show that water in the PCV was not above a first floor grating (OP+9.5m). The actual water level in the unit 2 PCV is significant because the unit 2 wetwell is assumed to be cracked and leaking after some booming noises were heard in the first few days of the crisis.
An attached thermocouple gave support to current temperature readings; although its readings were slightly higher (at worst case, 45.7°C vs 42.6°C), the maximum difference was just over 3°C. The internal wall of the PCV was shown covered with rust-coloured deposits.
The video was taken by a borescope small-diameter camera with light source inserted in a penetration at an elevation of OP+12.5m. It was also inserted with a thermocouple wire that measured temperature. The penetration was prepared by installing two protective plates that were then drilled through to create a space for the borescope to pass.