[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Plasma Torch Cutting
Forgivr me if this is a bit off thread, but something in your reply brought up a question. To what extent are graphite modeartors still used in reactors, ala Chernobyl Nuclear Power Plant? I'm sure I could get the numbers if I looked hard enough, but I'm asking on the off chance someone already has done the leg-work.
Floyd W. Flanigan B.S.Nuc.H.P.
-----Original Message-----
From: Franz Schoenhofer [mailto:franz.schoenhofer@CHELLO.AT]
Sent: Thursday, August 14, 2003 3:48 PM
To: NIXON, Grant (Kanata); 'Dave Biela'; radsafe@list.vanderbilt.edu
Subject: AW: Plasma Torch Cutting
-----Ursprüngliche Nachricht-----
Von: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu]Im Auftrag von NIXON, Grant
(Kanata)
Gesendet: Mittwoch, 13. August 2003 23:45
An: 'Dave Biela'; radsafe@list.vanderbilt.edu
Betreff: RE: Plasma Torch Cutting
Dear Dave,
(1) Chemistry: You are non-specific on the type of contamination on the
surface. But this item is important in order to understand the possible
chemical reactions that can take place.
As an example, C-14 contamination in an oxygen-rich environment (air) (+
heat) would prove a much different sort of radiological hazard (e.g., via CO
and CO2 formation) than would, say, Cs-137 contamination.
(2) The physics describing the release of contaminants or other particles
adhered to surfaces due to heating is a fairly well-known subject (adhesion
w.r.t. volatiles). This is a surface physics item that ought to be familiar
to semiconductor and optics people.
------------------------------------------------------
Dave,
Unfortunately I cannot give you a straight answer, but only a few hints.
A contamination by C-14 will be a very low radiological hazard, because both
CO and CO2 are gaseous and will be diluted extremely fast. A very small
fraction will be absorbed in the lung, but I guess that most of those gases
will be immediately exhaled. In any case the radiotoxicity of C-14 is very
low.
Cs-137 (or rather Cesium-compounds) are volatile above a temperature of
about 450 C, so they will volatilize at the heat of a plasma torch. The same
is true for quite a few other radionuclides. You may take as a guide the
emissions from the Chernobyl Nuclear Power Plant, which were caused not only
by the explosion and the meltdown of nuclear fuel, but mostly because of the
graphite burning for about 10 days.
I agree, that the type of contamination will of most importance, but you
have to consider the radiotoxicity of radionuclides as well.
Franz
************************************************************************
You are currently subscribed to the Radsafe mailing list. To unsubscribe,
send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
radsafe" (no quote marks) in the body of the e-mail, with no subject line.
You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/
************************************************************************
You are currently subscribed to the Radsafe mailing list. To unsubscribe,
send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
radsafe" (no quote marks) in the body of the e-mail, with no subject line.
You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/