Your fears are well placed the disaster in Japan was bigger than chenobol made so by the fact that spent plutonium and Uranium rods were stored in the outer layer compartments in pools of cooling liquid. When the outer containment's blew there tops they sent 100's of kilograms of highly deadly elements into the atmosphere and sea. Why Plutonium these reactors we designed to burn weapons grade material after American and Soviets agreed on a nuclear arms reduction program.
Reports of radioactive elements such a radioactive cesium in the food supply are common.
I would suggest not to go at all. if you must there are supplements such potasuim iodide you cant take to protect the most vulnerable part of the body the thyroid gland.
Dr. Helen Caldicott: The Medical Implications of Fukushima, Nuclear Power and Nuclear Proliferation http://www.youtube.com/watch?v=8hTuqy6RpFQ
http://emergency.cdc.gov/radiation/ki.asp
http://www.nytimes.com/2012/01/22/wo...anted=all&_r=0