I would still worry, even the Japanese people know their government is not completely honest with them - and neither is ours. They would probably say it's because people will panic - sure they will. And the higher ups will just take off in some jet and wait it out in a safe spot halfway across the world - if need be.
Note I said worry - I'm not digging a fallout shelter. I'm just sick and tired of the official releases concerning anything (from medical procedures to nuclear meltdowns) where they tell you its no risk, - it's no worse than having a trillion chest xrays in one day . Then to sugar coat that they'll add you get that much exposure just being outside on a sunny day. I'm not buying any of that but, what can you do??
Life gives us so many opportunities to worry - just pick the one you like best and work at it. My mother schooled me so well in the art of worrying that she got to retire early and I took over.