No reason for iodine tablets if a RTG got splattered across the landscape. If iodine tablets do any good there was fission involved. The threatening isotope i

No reason for iodine tablets if a RTG got splattered across the landscape. If iodine tablets do any good there was fission involved. The threatening isotope is Iodine-131, half life of 8 days. It's only found associated with fission or with atom smashers. It poses basically no direct harm, the threat is your body taking it up and putting it in the thyroid where it decays and irradiates the thyroid. Hence when it's a threat you take potassium iodide tablets--basically flooding your body with as much iodine as is safe. The fallout iodine gets diluted by all the iodine in the tablets, you absorb a much lower amount of the dangerous stuff.