On 19/02/2013 10:15, Tim Streater wrote:
In article ,
Andy Champ wrote:

On 19/02/2013 09:54, Tim Streater wrote:
In article ,
Andy Champ wrote:

On 18/02/2013 22:44, John Rumm wrote:

Do you have a reference, I could not find iodine in any of the
Uranium
decay chains I looked at - perhaps I am missing one?

It's not in the decay chain. But if you hit U235 with a neutron it
can be one of the fission products.

OK so it's a fission rather than a decay product. That should mean, I
suppose, that after a reactor is shut down, no more is produced. And
what is there will, after a year or so, be gone.

The half life is 8 days. So after 8 days half is gone, after another 8
3/4, another 8 7/8ths... 53 days is 1% remaining. 160 days takes you
to 1 part in a million left. Not even a year until it wouldn't be
noticed.

When I did the calculation, I assumed that 100 tons of it had been
released (or was within the buildings, perhaps).

After two years you'd have about 100 atoms left.

As a matter of interest, how many atoms would an individual need to
consume to have an identifiable increase in likelihood of disease? I am
thinking thyroid cancers but there is some suggestion that some other
thyroid diseases might also have radio-active iodine isotopes somewhere
in their aetiology.

That mythical thing, an average human, produces around 85 micrograms of
thyroxine every day. Already a fairly small amount but hige compared
with 100 atoms.

--
Rod