This is a very interesting article written by scientists from the U.K. They visited Fukushima, and went to the Daiichi power plant.  (The one that is owned by a Tokyo company and supplied energy to Tokyo. It melted down.)  It is an area I NEVER go to.  (It’s off limits unless you receive permission.) It’s a long article, but I recommend it.

http://physicsworld.com/cws/article/indepth/2018/jan/09/what-next-for-fukushima