One is to take potassium iodide, which protects the thyroid. But there is no need to take this if there is no problem with radiation. Here is more information on postassium iodide from Scientific American: Does Potassium Iodide Protect People from Radiation Leaks?
Another recommendation is to eat a diet of brown rice, miso soup, and sea vegetables. This diet apparently saved lives after the bombing of Japan in 1945. Since then, researchers have found that sea vegetables contain a substance that selectively binds radioactive strontium and removes it from the body. (Kelp tablets offer the same benefits as seaweed in its natural form.)
Another recommendation is to take the activated liquid zeolite drops recommended for toxic chemical detox. They also remove radiation from your body. Taking these drops will protect your health from both toxic metal/chemical and radiation exposure.