via EX-SKF / January 18, 2014 / TEPCO released the video which was being taken by the robot on the first floor of Reactor 3 and which was being monitored by a TEPCO employee who noticed the water.
The flow looks significant and fast.
Location of the MSIV Room:
Radiation levels on the 1st floor of Reactor 3, from yesterday’s post:
The main steam isolation valve (MSIV) is one of the two most important safety systems in a nuclear reactor (the other one being the control rod drive mechanism). It seals off the water/steam from the Pressure Vessel in case of an emergency (like a big earthquake). This MSIV system is not supposed to fail.