One of the great things about radiation is that we can measure, accurately, it in infinitesimal units. We can measure radiation that hits us from stars that are hundreds of light-years away. We can measure the radiation from the so-called 'Big Bang" that happened billions of years ago.
The bad thing about it is that level of accuracy about something that can't be seen, felt or heard is open ground for fear mongers, scheming politicians and technically illiterate media clowns looking for ratings to create panic simply because they can all make a buck off it.
Fear and panic are great profit opportunities.
Personally, I'm incredibly impressed with the design of these reactors. The spent fuel pools not as much, but all in all, a complete station blackout after a 9.0 earthquake and a 8 meter tall tsunami, the plants dropped offline, and even without coolant, none of the expected horror stories have panned out in the slightest bit.
But then again, the most strident doom-mongers are the same old anti-nuclear crowd as always, working to drum up the level of fear for their own political gain, because heaven help us if they don't have a tragedy to usurp and exploit.