Is it vapor or smoke?
Now if you can stomach it, check out this video from about an hour before #4 starts blowing smoke or steam. That beam or whatever it is, on the right area near the lower part of the stack, came out of the ground. The anti-nuke people are going ape-crap over this. I have no idea what came out of the ground over there earlier tonight. And it appears that the smoke/steam is coming from possibly multiple sources since it was rolling into the camera view from the far right.
2012-02-06 17:08 light rays connects to spot light @ tepco fukushima
That video is a little over 1 hour before #4 started blowing smoke/steam. And around the time that TEPCO decided to inject boric acid into #2. Also reports that other SFP are getting too warm #3 and #5.