Earlier this week heavy snows at Fukushima Daiichi seem to have cleaned off the unit 1 cam lens so the pattern that was previously visible is gone now (see here for illustrations).
However, the Fukushima Daiichi unit 4 webcam shows much heavier than ordinary emissions.
Examine these two comparative shots.
The first screenshot is from February 6, 2017, at 1:53:
The second screenshot is from March 19, 2017
Here is a close-up cropped shot
One wonders whether structural conditions are deteriorating at the plant at an accelerating pace....