terryh on thu 24 jun 99
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what is this? don't they teach common sense in school, not to mention,
physics and chemistry, and evolution? everything is dangerous if consumed
by a large amount. (well, vitamin C may be an exception? i bet not.)
somebody wrote:
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=3EI'll only pick out one, obviously wrong statement here=3B the one about
=3Ecobalt not undergoing any reaction in nuclear reactors. This is about =
as
=3Ewrong as it is possible to get. Cobalt has a large neutron absorption
=3Ecross section, which is a technical phrase meaning that cobalt readily
=3Eabsorbs neutrons in the reactor. That is why it works as a control.
=3EInserting cobalt control rods into the reactor core dampens the nuclear
=3Efire, like throwing water on a piece of burning wood. In the process,
=3Ecobalt becomes the highly radioactive, long lived isotope, cobalt60. In =
my
l=3Eine of work, we have to place stringent limits on cobalt in other metals
=3Eprecisely to avoid this effect, which would otherwise make our physics
=3Eapparatus too hot to handle after a few year's exposure in the =
experiment.
=3EAll of which has nothing whatever to do with studio pottery.
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you are wrong. you may be talking about cadmium (Cd), which has a large
thermal neutron cross section and hence, is used as control rods in nuclear
reactors. not cobalt. and, anyway, the large neutron absorption cross =
section
has
no bearing to nuclear toxicity. boron (B) and chlorine (Cl) also have large
cross sections.
and so what? are you going to get rid of NaCl salt out of our kitchen?
tasteless.
if cadmium is dangerous/toxic, it's because it is =22heavy metal=22. anyway,=
how
many
neutrons are flying around in your studio, do you know? zero. cobalt 60, =
long
lived?
it's just 5 yrs. that's a problem in some applications. it'll be more useful=
if
it had longer
life time. instead we use cesium (Cs) with life time of 30+ yrs in many
radioactive tracing
in spite of its low energy gamma rays.
please don't witch-hunt blue cobalt out of our studio. it's already so
expensive.
it doesn't need any demagogue.
terry hagiwara
e-mail: terry.hagiwara=40halliburton.com (W)=3B terryh=40pdq.net (H)
web: http://www.geocities.com/SoHo/Cafe/3755
Gavin Stairs on fri 25 jun 99
At 09:32 AM 6/24/99 EDT, you wrote:
...
>>Inserting cobalt control rods into the reactor core dampens the nuclear
>>fire, like throwing water on a piece of burning wood.
...
>you are wrong. you may be talking about cadmium (Cd), which has a large
>thermal neutron cross section and hence, is used as control rods in nuclear
>reactors.
...
Oops. There I go again. This is correct. The control rods are not
Cobalt. The rest of what I said still stands, though.
I would add that I'm not trying to say that Cobalt is a bad thing in
pottery glaze. It is one of the least bad of the strong colorants. My
objection is to the notion that a non-durable glaze is ok if all you
release is some cobalt. I prefer the notion that a glaze which is durable
and releases no significant quantities of anything is the goal. We can now
continue with the debate as to how much cobalt is significant.
Gavin
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