It's approximately 120 miles (as the crow flies) from the melting down nuclear plants to
Disneyland Tokyo. It's located roughly south from the nuclear plants (180 degree azimuth would be due south--DLT is at about 200 degrees).
As of today, Japanese officials have set the evacuation zone at 12 miles. However, U.S. officials have just challenged that assessment, and have advised U.S. civilians and military personnel to stay at least 50 miles away. The UK has just advised its citizens to leave Tokyo and all locations to its north.
In very basic terms, the U.S. advised evacuation zone reaches nearly halfway to DLT.