[Test-Equipment] Radioactive Tube Stamp

[rbethman]

On 7/3/2010 3:26 PM, Richard Knoppow wrote:
>
>       There are a lot of tubes with thoriated tungsten
> filaments, I think most of the Eimac triode and tetrode
> transmitting tubes have them.
>       Thorium was used in some types of optical glass
> especially for aerial photography lenses during WW-2. Some
> of these had enough radiation to cause "browning" of the
> glass over a period of many years. Thorium lends some
> desirable optical qualities to the glass but it was
> discontinued after the degree of radiation was discovered.
> Some sources claim that the thorium was an accidental
> ingredient, included as an impurity particularly to
> lanthanum, but that is not the case: thorium was delibrately
> used and is included in the formulas shown in the patents
> issued to the National Bureau of Standards, where rare-earth
> optical glass was developed. Even some high-performance
> lenses for domestic rather than military use contained some
> thorium elements. I don't know what the radiation levels of
> these lenses are but I understand that the decay products of
> thorium may be more hazardous than the thorium.
>
>
> --
> Richard Knoppow
Thorium is indeed a radioactive element - IF - it is Thorium 232.

The decay product of Thorium 232 is an alpha particle.  This is a not 
well understood method of decay to the "lay" person.

Use the example of Thorium being added to a glass compound.  The glass 
in and of itself protects the individual from the alpha decay products.  
Alpha particles CANNOT penetrate "unbroken" skin, paper, or glass.

Therefore they become a non-issue.

The use of Thoriated Tungsten filaments in a vacuum tube does NOT 
present a danger to the user/operator - UNLESS the glass envelope is 
broken.  *IF* one were to "inhale" the alpha particles, THEN significant 
damage can be done.

Significant is a "relative" term.  A "few" alpha particles being inhaled 
is not a *REAL* issue for the human body.  On the other hand, the 
inhalation of a LARGE amount IS.

If someone should happen to break a Thoriated Tungsten filament tube, 
simply place the entirety of it and its parts wrapped in paper or such, 
(to prevent tearing the NEXT layer.), and place it in a "Zip-Loc" bag 
and dispose of it as normal trash.

If it is done in this manner, it will NOT be a danger.

That is unless one desires to contact "Hazardous Waste Officials".  IF 
you do so, all bets are off!

Technically your home smoke detector should be considered hazardous 
waste, as also the compact fluorescent, or ANY  fluorescent light bulb.

The smoke detector uses a radioactive substance called Americium.  The 
fluorescent bulbs contain very small amounts of mercury.

There is "balance" in things.  One should not have sudden fears that are 
misplaced.   This is one of those areas that REQUIRES "common sense".  
Although one might consider that "common sense" is NOW uncommon!

Bob - N0DGN