who does! Fortunately a trip to Hokkaido is NOT going to do either of those, here's a few reasons why:
At the height of the Fukushima nuclear reactor (near) meltdown massive amounts of radioactive material were released over a 24 to 48 hour period. The background radiation levels in Tokyo were 20 times higher than normal BUT that does was the equivalent of getting an abdominal x-ray (would your 13 year old refuse an x-ray for the same reason?).
A couple of things to note abut that radiation spike in Tokyo: the city is only 220kms from the plant. Where you are going is over 550kms away!
There is no indication that any significant radiation has settled on the island of Hokkaido.
Some beef from cattle which grazed in Fukushima prefecture did find its way into supermarkets, but a health official said the level of contamination was so low you'd have to eat the beef everyday for a year for it to even register in your body (which is a long way below any danger level).
The thing about radiation is that a large dose over a short time is dangerous, a small dose over a very long time is also dangerous: you and your daughter will be there for a short time and well away from any contamination, so if there is any radiation it will be an infinitesimally small dose over a very short time. Tell her to stop watching the news and start researching the FACTS for herself, he he he.
I have a 5 year old boy and a 16 month old girl - I'd have no hesitation in taking them to Hokkaido. about 7 years ago