Taking care of Body during these times is probably a good idea. We had high levels of cecium around April 17th here in North America.
What to eat or not to eat in North America, Europe and others after the Fukushima accident:
Leafy greens are the first to be contaminated by cesium, or mushrooms (that concentrate radionuclids).
Miso and certified organic (important) seaweeds are excellent, especially Kelp and arame.
The very serious health guide "Prescription for Nutritional Healing" only recommends to eat apples (for pectin), kelp, garlic (which also concentrates cesium, BTW) buckwheat (for rutin), avocados, lemons, and cold-pressed safflower and olive oil (for essential fatty acids), and to drink steam-distilled water. Authors James Balch (M.D.) and Phyllis Balch (CNC) also recommend to take supplemental calcium and magnesium, coenzyme Q10, Gluthatione + l-cysteine & l-methionine, Grape seed extract (antioxydant), vitamin B5 (can be replaced by brewer's yeast), selenium, lecithin (protects cell membranes against radiation), vitamin C, vitamin B complex plus extra inositol, and zinc. It also states that chapparal protects against radiation but might be toxic for the liver after a week.