You can use colloidal iodine as a daily suppliment. (increase dosage for radiation detected)
scroll down:
http://www.herbalhealer.com/newproducts.html
I use kelp powder like salt for lots of my cooking: stir-fries, soups, home fries, salads, salad dressing, stews, etc. You can also get the Dulce in ‘shaker’ form.
I use iodine - paint a “silver dollar” circle on my abdomen or throat and wait to see how soon it disappears. If within, say 2 hours, I do it every day until it takes several hours - which, I've read, is an indication that the body doesn't need any more for a bit.
I do the above to make up for our iodine depleted foods.
I wonder if my regular regimen would help to protect me against fall out? (I'm too far away to worry about Japan, but I am curious)