Joseph Herbert on tue 21 mar 00
Mia wrote: The uranium sold for pottery use is "spent uranium".
Nothing to be concerned about. It is a nice yellow glaze colorant for
cone 9 to 10. In a low fired lead glaze you can get a wonderful orange
red. If you cannot find it in ceramic supply places try a chemistry
supply place. However there are yellow stains that will give you the
same color effect. Mia in ABQ
The idea of Spent Uranium being sold to the public is interesting to
me. Perhaps Mia meant Depleted Uranium which is a different thing.
Usually in the Nuclear biz the term spent is applied to material that
has been run through a nuclear reactor and the fissionable atoms have
fissioned and the energy contained in those atoms is gone and the atoms
are spent. The atoms themselves are not gone, they have become two
smaller atoms (fission fragments) that often have rather nasty radiation
characteristics.
On the other hand, depleted uranium is produced by removing the
fissionable uranium (U235) from the mass of uranium leaving the less
radioactive material U238. This material is less radioactive, not
non-radioactive. In addition, both these materials have the same
chemical properties since they only differ by three neutrons in the
nucleus, a characteristic that does not change chemical properties at
all. The absence of the three neutrons allows U235 to split when it
captures a stray neutron, something that U238 generally does not do.
Any objectionable chemical characteristic, like producing heavy metal
poisoning, will be present in both kinds, equally.
What U238 will do when confronted with stray neutrons is absorb them and
change into some other kind of atom like Plutonium, as an example.
This particular reaction is the basis of nuclear weapons production and
the so called mixed oxide (uranium and plutonium) nuclear fuel cycle
used by Japan and other countries. Since the U238 that is in the
nuclear reactor forms Plutonium during its stay there, recovering the
plutonium (a material more fissionable than U235) more reactor fuel can
be produced without requiring more fresh uranium.
Aside from the problems with heavy metal poisoning, it is difficult to
know where one s depleted uranium came from. It could have come from
the process that removes the more fissionable material from original
virgin uranium metal. This would be uranium that went from ore to
metal to the processing plant and then out as depleted uranium. That
would be nice but there are thousands of tons of uranium metal
circulating in the world that are not like that. This uranium has been
through a nuclear reactor and then chemically processed to remove the
fission fragments and recover the plutonium. What is left after that is
also depleted uranium. A small but important difference is that there
may still be traces of the fission fragments or of the plutonium. This
could change the nothing to be concerned about to something very
different. Probably the person you purchase your uranium from is an
ethical person but the point here is you have no way of knowing just how
radioactive your uranium is and you cannot tell what characteristics the
trace impurities may have. You could do gamma ray spectroscopy.
Your customers deserve to know that the pot they are buying is
radioactive. They should also know that the glaze contains one of the
more soluble heavy metals. I have sustained no visible damage from
years of sleeping with my collection of orange pre-war Fiesta ware
with the possible exception of prolix writing but that is a choice I
make with knowledge and understanding. I am not sure a similar lecture
comes with the sale of that nice yellow coffee mug and juice beaker set.
We have not yet had discussions of the use of Radium Oxide as a glaze
colorant. It is really expensive and dangerous but there must be
someone out there who thinks it is a good idea and No particular
problem. Probably makes a bilious pink of some kind but with that
inner glow.
All nuclear non-proliferation treaties should include pottery glazes.
Joseph Herbert
| |
|
