[ RadSafe ] Iodine Chemistry of nuclear reactors in emergency cases

McNaughton, Michael mcnaught at lanl.gov
Wed Mar 23 17:06:04 CDT 2011


Thank you for the information. I have copied a few paragraphs from your message because I have a question about the information in these paragraphs.

Fission products are created as individual atoms so I suppose an individual atom of radioactive iodine is most likely to react with a different atom and form an iodide. I suppose it is less likely to find another iodine atom and form molecular iodine, I2. Is that correct?

So does that mean that after some time, there will only a small amount of radio-iodine in the chemical form I2? Is most of it in some other chemical form, perhaps in a form that can be collected as particulates on a filter?

Mike McNaughton
mcnaught at lanl.gov

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Franz Schönhofer
Sent: Wednesday, March 23, 2011 3:46 PM
To: 'The International Radiation Protection (Health Physics) MailingList'
Subject: Re: [ RadSafe ] Iodine Chemistry of nuclear reactors in emergency cases

Now let us go to the facts about iodine: 

One of the chemical speciations is "volatile" iodine, which simply is
molecular iodine, chemically characterized as I2 (two atoms form a
molecule). This is actually very volatile and if I want to smell iodine I
only need to open a semi antique powderflask with elemental iodine - it does
not boil at ambient pressure, but sublimates, which means it transfers from
solid phase directly to gaseous phase. In fact I need not open the flask,
only the glass window to the cupboard where I store it, because it is so
easily volatile.

Two other ones are the ionic forms of iodide I- and less frequently
occurring iodate IO3-. Those are less volatile, but occur in a nuclear

On the long term the organic species like methyl iodide will be formed and
they have a very different impact on the ecosystem.

The ratio of these species is reactor specific and very significant. Studies
exist for BWR, PWR etc. since decades. 

Molecular iodine will be mostly transported as a gas (like the rare gases),
iodide and iodate will be carried exclusively by aerosols. This might
already give you a coarse information about the different ways "iodine"

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