Least with Chernobyl most of the radioactive material is still inside the core, so can be contained.
It's not. Chernobyl didn't have a containment building, and the vessel containing the nuclear materials had its lid blown off, so all the radioactive material was blown up into the atmosphere and surrounding areas. It was so bad that robots used to clean it kept shorting out and dying, so they ended up having people run out, one at a time, grab a chunk of the material, and chuck it back into the containment area or take it to a disposal area. It was so bad that each person could do it once for no longer than 15 to 30 seconds, and then be sent home.
I wonder if the level of Fukushima radiation would be more visible if it also was near a forest instead of near the ocean:
http://en.wikipedia.org/wiki/Red_ForestYou can see chernobyl station in the back