Perhaps some of the heavy emissions I've been witnessing the last week or so are from the new incinerator, as suggested by an anonymous commentator a few days back:
Incineration of radioactive waste begins at Fukushima nuclear plant. The Mainichi, March 21, 2016 http://mainichi.jp/english/articles/20160321/p2a/00m/0na/004000cThe incinerator might be the source of the plume on the right hand side of the screenshot but does not explain the heavier emissions emanating from the top of unit 1, in the cropped second shot below:
Tokyo Electric Power Co. (TEPCO) has begun incinerating radioactively contaminated clothing and other waste on the grounds of the disaster-hit Fukushima No. 1 Nuclear Power Plant in an effort to reduce the volume of waste.
A three-story incineration facility has been built on the north side of the plant grounds. Every day around 7,000 people work at the Fukushima plant, creating a massive amount of waste in the form of used radiation suits, gloves and boots. Pre-disaster incineration equipment was destroyed by the March 2011 Great East Japan Earthquake and tsunami, which led to the construction of the new facility.