Re: Iodine tablets

[dsimpson@unlnotes01.unl.edu]

Regarding the question of whether KI should have been distributed to the local
population after the Japanese criticality, it would seem to me that the answer
would be no.  KI would be appropriate in a situation involving a large inventory
of radioactive iodine (unlikely in a criticality accident not involving a
reactor), where there was a pathway to the environment (unclear to me in the
Japanese accident), and where KI was already distributed to the local population
prior to the accident(based on the statement in the EPA Manual of PAGs that
recommends administration within 1-2 hours of exposure).   Also the history of
non-reactor criticality accidents has indicated that internal exposures and
environmental releases have not been the  major problems, though the Japanese
accident does have some unique features including a nearby general population.

KI would be most effective following a reactor accident in a dry environment
with an open path to the atmosphere (such as Chernobyl or Windscale).  My
understanding is that in a wet reactor accident environment (TMI), much less
iodine will escape though the large inventory is still present.

When I lived in Tennessee,  it was also my inderstanding that TVA had
distributed KI tablets to local residents around their reactor sites.  I also
heard stories that some of those residents had self-administered the tablets
prior to medical X-rays or nuclear medicine studies as a protection against the
radiation, despite instructions to the contrary.  Perhaps someone from TVA can
let us know how their KI distribution system worked and whether it is still in
place.

+++++++++++++++++++++++++++++++++
David R. Simpson, Ph.D. CHP
University of Nebraska - Lincoln
dsimpson1@unl.edu
+++++++++++++++++++++++++++++++++


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