Fukushima

[Khandro]

French advisors are helping the Japanese to tackle the problem of radioactive water. It is said that they are attempting to remove the contamination, is this possible?

[Red_John]

most of the contamination is radioactive isotope of iodene and that has a half life of 8 days, so the effect will decrease exponentially over time. Not sure what they can "remove"

[jomifl]

washing usually works for contamination that hasn't been absorbed by plant or animals.

[Khandro]

When you say "Washing" do you mean it's a sort of filtration process; clean water comes out, and the radioactive element is separated and contained?

[jomifl]

Decontamination processes have been well developed since the exploitation of nuclear fission. Workers externally contaminated with radioactive materials are washed and scrubbed, soluble and particulate radiactive are removed from the water by ion exchange and filtration respectively. The same basic process can be applied to inanimate objects too. Chemical processes can be used to strip off contaminants adhering to surfaces. Contaminated material that has little value can be collected and stored safely.

[Khandro]

jomifl, So if I read you right, you are saying that what we call "Radioactivity" made up of physical particles? I always thought it was some sort of force, like magnetism or electricity, I never saw it like that; interesting, thanks. As I age I seem to know less and less about more and more!

[slinky.kate]

I'm going to guess it's ridiculously hard, though with the half life so small you would hope that it was converted to iodine-129 before you started drinking it.

Iodine-131 is one of the most energetic radioactive decays and is extremely soluble in the thyroid gland causing thyroid cancer. Though at the levels we're seeing (which is about 2 millionth the amount that is in Japan) it wouldn't be a huge problem.

In our house we have a filter on our tap which gets rid of any metals which are in the water, this would filter out any radioactive iodine before we drank it!!

[slinky.kate]

Radiation is the emission of an alpha, beta or gamma particle from when an unstable molecule, like iodine-131 decays.

These can consist of electrons, neutrons or protons from the atom, it's these emitted particles that are radioactive!

You can say that they are physical particles as they have a mass.

[jomifl]

Kate..Iodine is not a metal so don't rely on your filter unless you know it traps anions.

[jomifl]

Khandro .. as Kate said, the particles are those that atoms are made up of. They are emitted by unstable isotopes (which are atoms with one or more extra neutrons) when they decompose to a lighter isotope or lighter elements which may themselves be unstable isotopes. Emitted electrons are the least harmful and barely penetrate human skin whilst emitted neutrons are the most harmful as they penetrate matter quite deeply and can damage molecules vital to life. It is the unsable isotopes that are 'radioactive contamination'. Chemically and physically these unstable isotopes behave like their stable 'sisters' so will respond to the same filtration / absorption procedure.

[jomifl]

Kate..cations^

[slinky.kate]

Well noticed jomifl, I wasn't thinking when I sent the last message, was just looking at the table in my head thinking it's at the bottom, forgot how far it was to the right.

The filter on the sink is similar to a cation/anion exchange column therefore, with no counter ions in the mobile phase that would be really capable of moving the iodine (anion, see I got it right this time) it will be held on to the filter by size and charge so should be ok!

[jomifl]

Kate..would chlorine cause a problem in displacing the iodine? not that there is enough radioactive iodine to worry about (yet) :-)

[slinky.kate]

I think you mean chloride jomifl?

The filters are changed every 3 - 6 months, which should be enough to store the amount of anions/cations which you should expect in that time period.

Due to how packed the column is I think iodine would get trapped more due to it's size than charge. I'm not sure of the oxidation state of iodine at pH 6 - 8 but I believe it could be +7, which comparing it to chloride of 1 I wouldn't expect the chloride to displace it.

Though who knows, depends what the iodine picks up on the way along. The chelating agents found in water could change it's properties quite dramatically.

[jomifl]

Hi Kate, I was making the assumption that your water is chlorinated, if not then please disregard my comments. If it is chlorinated then chlorine /chlorate ions might displace iodine ions, but only if there is no other place for them to go. :-)