From Kyodo News (3/18/2012):
Kyodo News conducted the poll of 5th graders in elementary schools and 2nd graders in junior high schools who evacuated their homes after the Fukushima I Nuclear Power Plant accident but remained inside Fukushima Prefecture. Of 225 students who responded, 72 students (32%) were "worried about radiation for the first time [in their lives], after the nuclear accident happened), it was revealed on March 18.
3 students (1%) had worried about radiation even before the accident. On the other hand, 138 students (61%) "were not worried about radiation" even after the accident. It shows the mixed feeling that children have [toward radiation] in the "safety myth" created by their parents' and grandparents' generations, even as they lived near the nuclear power plant.
[I'm not sure what Kyodo means with the last sentence, as it doesn't sense. So the following is my interpretation of what Kyodo may have meant.]
As to their fellow students who evacuated to outside Fukushima Prefecture, 34% say they "understand", and 31% say they "want them back".
Kyodo News calls it "mixed feeling", but looking at the numbers it doesn't seem mixed. Nearly twice as many students say they don't care. There is no poll to compare that was taken prior to the accident, so there is no knowing what percentage of students had feared radiation prior to the accident.
From what I hear, people who have remained inside Fukushima are doubling down, so to speak, more than ever determined to live a normal (i.e. pre-nuke accident) life.
Dr. Shunichi Yamashita seems to have succeeded in securing his research subjects.
If you haven't seen the BBC documentary on children in Fukushima, please do so. The title of the documentary is "Japan's Children of the Tsunami". There may be a copy still somewhere on Youtube or Dailymotion.
It's not the matter of whether they worry about radiation or not. It is about whether it is right for any adults to keep these children, looking healthy and well-adjusted for the most part in the BBC documentary, trapped in Fukushima.