(UPDATE 1/18/2014) Video, additional information in the new post. The water is flowing fast.
No images, videos, details yet.
From TEPCO's email alert for the press in Japanese (1/18/2014):
Water leak found near the Main Steam Isolation Valve Room on the 1st floor of Reactor 3 at Fukushima I Nuclear Power Plant
Today (January 18) at around 2:40PM, our employee who was monitoring the images taken by the camera mounted on the robot for removing the debris from the Reactor 3 building found the water running, at 30cm wide, from near the door to the Main Steam Isolation Valve Room located in the northeast area of the 1st floor of Reactor 3 into the floor drain funnel near the door.
This water is flowing into the floor drain funnel that connects to the floor drain sump in the basement of the reactor building, and there is no leak from the reactor building to outside.
There is no statistically significant change observed at the monitoring posts and in the plant parameters (amount of water injected into the reactors, temperatures at the bottom of reactor pressure vessels, temperatures inside the containment vessels, etc.).
We are currently investigating the situation of the leak and the cause of the leak.
The ambient air dose rate near the leak is about 30 millisieverts/hour.
Reactor 3 first floor radiation levels (from my 7/23/2013 post):
Compared to other reactors that had explosive events (Reactor 2 did not have hydrogen explosions like Reactors 1 and 3, but some kind of event did seem to happen in the Suppression Chamber), Reactor 3's radiation levels are markedly higher.