I'm not seeing this from anywhere else (more reliable) but Gizmodo says Mystery Steam Over Fukushima Could Be Sign of Another Meltdown "The newest update in the highly disconcerting series of devastating failures that is the Fukushima cleanup effort is troubling to say the least. Tepco has confirmed that (unexplained) plumes of steam have been rising from the mangled remains of Reactor Building 3. In other words, there's a chance Fukushima could be in the middle of another meltdown."
The source is The Ecologist and have three theories:
- Possibility 1 - a meltdown is taking place
- Possibility 2: 'corium' has reached groundwater
- Possibility 3: rainwater on stray fuel elements
Update: Much better info, Fukushima Meltdowns: A Global Conspiracy of Denial