On 17/02/2013 05:43, Windmill wrote:

But they give iodine tablets to those exposed.
What does I131 decay to? Is it also radioactive? If so, what in turn is
its half-life?

The whole point of iodine tablets is to provide all the iodine that the
person's thyroid needs using known non-radio-active iodine. Thus the
thyroid will not take up any radio-active iodine in the environment.

Do bear in mind that thyroid hormone is then distributed to every cell
of the body so radio-active iodine is a wonderful way of giving people a
dose of radiation to their entire body! (Whereas a modest excess
iodine/iodide can often be excreted quite readily. And hopefully the
radio-active iodine would be so excreted.)

(Technically, they often use Potassium iodide.)

Have a look he

http://en.wikipedia.org/wiki/Isotopes_of_iodine

--
Rod