Sorry, the previous poster was right. Iodine does not neutralize radioactivity. Nothing neutralizes radioactivity, not even slightly. We have no way to destroy it. It only goes away by itself, gradually.

stable iodine fills up your thyroid like a full cup of water. When the radioactive iodine comes along, if your cup is full, the radioactivity can't get in, it just spills over and you pee it out. There is not enough iodine in seawater to fill up your "cup." seawater and creatures from the pacific are best avoided now, and for a ling time to come. I'm sorry, humanity has no way to fix it.