After the Fukushima triple meltdown in March 2011, the Fukushima prefecture set up a program to check children under eighteen at the time for thyroid problems. According to the Japan Times, Friday it was announced that, as of the end of 2013, 33 confirmed cases of thyroid cancer had been found. Three months before, the number was 25. 75 children were "suspected" of having the disease.
Of the 375,000 children eligible for the checkups, about 270,000 have been screened. Thyroid cancer is very rare in children. In the United States, the average incidence for children under fifteen is 1.6 per million. You would not expect to find more than a single case in a sample of 270,000 children; more likely you wouldn't find any at all.
A local "panel of experts" said (naturally) that "it is unlikely the disease was caused by exposure to radiation from radioactive materials from the stricken power station." However, no explanation or hypothesis was offered as to why, exactly, the children exposed to the radiation where getting thyroid cancer at rates 76 to 174 times what would be expected.