Potassium Iodide or alternatively, Iodate will protect only your thyroid from exposure to radioactive iodine. They do not protect you from other radiation exposure at all. Except for your thyroid, you are no more protected after taking these than you were before.
-bc
Short time near it, stay as far away as you can, (use improvised remote tools to move, etc.), use any shielding you can, get rid of clothes, shower, esopecially hair.