How would Japan's possible Chernobyl like nuclear crisis affect the US?

According to the International Nuclear and Radiological Event scale, the radiation coming from Japan's Fukushima plant is a level 6 out of 7. If it reaches level 7 that means Japan will be another Chernobyl meltdown where residents will be forced to evacuate possibly all of Japan. Also possible that the radiation may travel to Alaska, Hawaii and Western parts of US. The possibilities now are stronger than ever and if it were to happen how would it affect everyone living in US and where would the Japanese flee to live?