Jon Singer on sun 14 jan 01
The Uranium that is available to us as potters is depleted,
which is to say that the fissionable U235 has been removed
as well as modern technology can do so. This leaves mostly
U238, which is vastly the more common isotope in the
first place.
U238 is just barely radioactive, with a half-life of 4.5 BILLION
years or so, and does not represent a radiation hazard. If you
have a chunk of the stuff, just coat it with clear fingernail
polish, and it becomes a reasonable doorstop.
Just FYI, U235 has a half-life of "only" about 710 million
years, also a _very_ long time. Remember, the longer the
half-life, the less energy is emitted during any given period.
Radiation just isn't the issue here. The _real_ problem with
Uranium is that it is just astonishingly toxic. It and all of its
cousins (the Actinides) are pretty horrendous. With most of
them, ingesting even milligrams spells _serious_ trouble or
even death. I think Arne =C5se is very brave and _very_ crazy.
As to Potassium, the long post is technically sorta correct -- there
_is_ a radioactive isotope, and we all _do_ have some of it in us,
and that means that _we_ are radioactive.
OTOH, according to my copy of The Handbook of Chemistry
and Physics, ordinary K is about 0.00118% K40 (!), it has a
half-life that is over a billion years (!), and basically you can just
blandly ignore it. It is a non-issue.
The person who said that you expose your guts to radiation if
you take potassium supplements has grossly overstated the case --
the excess is probably undetectable.
Just by the bye, Vanadium is radioactive as well. The most
common isotope, however, has a half-life of 6 million billion
years -- got that? Six times ten to the fifteenth! If you want
to observe few disintegrations you take a kilo of the stuff,
sit your detector next to it, and put on several albums of your
favorite music. You'll be waiting for a while... Again, however,
the chemical toxicity is pronounced. Be careful when you
use V2O5.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In fact, I think that in general we have a whole lot more
to be worried about with chemical toxicity of our materials
than other issues. Enough of this radioactivity scare garbage,
okay?
Cheers --
jon
Gavin Stairs on sun 14 jan 01
At 01:02 PM 1/14/01, you wrote:
>The Uranium that is available to us as potters is depleted,
>which is to say that the fissionable U235 has been removed
>as well as modern technology can do so. This leaves mostly
>U238, which is vastly the more common isotope in the
>first place.
>
>U238 is just barely radioactive, with a half-life of 4.5 BILLION
>years or so, and does not represent a radiation hazard. If you
>have a chunk of the stuff, just coat it with clear fingernail
>polish, and it becomes a reasonable doorstop.
This is not correct. Depleted Uranium still has about half the U235 left
in it, and U238 is not a negligible radiation hazard. From the practical
view of a casual user of uranium in glazes, there is no real difference
between depleted and natural uranium.
Uranium is a controlled substance in most of the industrialized world, and
it is a moderate to severe hazard, depending on how you treat it. For
those who are apt to believe misinformation, it is by far the better
strategy to leave it strictly alone. Breathing any kind of uranic dust is
as good a way of encouraging lung cancer as I know. A significant fraction
of the hazard from dust particulates comes from uranium in soil and coal,
etc. Uranium is an unavoidable fraction of our Earth's crust, but the
level is well below a percent in most places. There are some elevated
concentrations in places like Oka, Quebec, and elsewhere.
In any event, this subject has been well discussed on this list. Please
consult the archives. Look for uUranium and Fiesta.
Gavin
Gavin Stairs
Stairs Small Systems
921 College St., # 1-A
Toronto, Ontario, Canada M6H 1A1
phone: (416)530-0419 stairs@stairs.on.ca
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