Dissolve them up and precipitate the iodine with silver nitrate. Make sure it is iodine though and not iodate, either one will do for saturating your thyroid with stable iodine. If it is iodate the solubility product is a bit higher than for iodine, and it may be more appropriate to precipitate the lead salt of iodate. Also, the iodine doesn't "block" radiation, it just gives your body enough iodine that it doesn't need to absorb anymore, which in the case of a nuclear accident would be radioactive and would increase your risk of thyroid cancer.