David, do you want to listen to scare merchants, or scientists on this matter? You can always find someone willing to try and scare you out of your wits. Or you can apply the scientific method -- which is, after all, what all astronomy/optics is also based upon!
Take a look at this latest paper on radiation-risk levels in Japan, just out in PNAS:
http://www.pnas.org/content/early/2014/02/19/1315684111