Its not only possible, its probable, due to japan being on the edge of a clockwise jet stream (9 oclock) while we are at (4 oclock) on that same stream. But the levels will be so minimal that you wouldn't even notice..
err.., i had to repeat this a few times to people at my work who were wondering the same thing so here it goes..
Chernobyl had a graphite based fuel source, making it possible to be carried much further at much higher dosages, These plants (which were sold to japan by GE, which is now GE-Hitatchi) have a more liquid and gas bassed fuel source, which dissipate much faster into the atmosphere.
300-rads is the equivalent of 75-100 Rem (milirems). People at my work push 100-200 milirems in their body daily and are alotted 300 milirem per lifetime.. Its when you get over 350-400 Milirems where effects like nausea and diarrhea occur