Check these out: http://www.ebay.com/itm/10g-99-8-Iodine-...=item20fc9056a5 if that's for emergency only. You can protect such an ampule in a piece of thick walled metal tube. I think, it should survive a very long time 100% sealed.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.