Use of unsealed thorium in TIG Welding

[b.mckavanagh@cqu.edu.au (Byron McKavanagh)]

To Radsafers:
>Could you be specific which manufacturers and which Aluminium Oxide
>wheels?  Are
>you sure the use of Thorium is intentional?
>
>bill
>bkolb@arinc.com
>_______________________________________________________________________________
>Subject: Re: Use of unsealed thorium
>From:    radsafe@romulus.ehs.uiuc.edu at smtpgate
>Date:    5/13/96  1:44 PM
>
>Some manufacturers use thorium in the constuction of aluminum oxide grinding
>wheels.  Tungsten welding TIG rods are sometimes thoriated also. Doug Turner

Coincidentally, I received a call yesterday from an RSO, Mr Iain Morrison,
in industry who has been shown "Thoriated" welding rods, and was getting
0.6 uSv/hr at the surface of the packet (gammas only.)  The small print on
the seal of the packet said "radioactive".

The rods are:
Thermadyne (TM)  Tweco (R) Tungsten electrodes, 10 each to a packet.
AWS Classification - EWTh-2, Ground Finish, 2% Thoriated Tungsten,
made in USA by Osram Sylvania Inc, Chemical & Metallurgical Products,
Towanda PA 18848.

The enclosed safety information was difficult to read, but stated the
material contained ThO-2, and then had a figure of 1 x 10*-12* uCi/ml.  (Is
this in the rod, or in the fumes generated?).

These TIG rods are obviously deliberately thoriated.  They have been used
"for hard facing for many years - as long as the workshop Engineer can
remember - they keep them locked up in a filing cabinet as they are
expen$ive!!"

Does anyone know why, and what would be the risk in using these in an
unventilated area?
 I understand that fumes from TIG welding are normally removed from the
work area by a suction line & vented outside.

Iain and I are very interested in any information that could be provided.
Thanks in advance.


---------------------------------oOOo-(_)-oOOo--------------------------
Byron McKavanagh,
Radiation Officer,
Department of Applied Physics,
Central Queensland University
Ph 079-309625                   Fax: 079-309209
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~)(~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Just remember you are unique.  Just like everyone else."
(Dictionary of Cynical Quotations, 1996 ed.)
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