As far as the quake, where it hit was a relatively small town in rural surroundings. It was quite a distance from Tokyo. Having said that, if there is a real nuclear meltdown, the whole country may be SOL, and depending on the direction of winds, who knows how much of the world (including at least one of our coasts) will be affected by radiation.
Whole country? Not likely. These things following predictable patterns of disbursal and deposition. If there is a major effluent release, the plume will track a reatiely narrow line over land following wind direction. Particulates that end up in the ocean will become so diffuse as to be non-existent. Gamma would all be local and temporary. Too soon to write off Japan. This is not the movies, and no one in the industry can watch “China Syndrome” with a straight face. Don’t work that way.