Re: Radioactive material on CV990 ?

Date:         16 Oct 97 00:44:11 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>I heard that the rudders of the Convair 990 had counterweights made out
>of uranium.

I don't know about the 990, but I've heard that the 747-100 has some
uranium in the outer wings to dampen flutter that was identified in
flight testing.  This may just be an unsubstantiated rumor, though.

>- What type of uranium was this ?

It almost certainly was 238U with only minor "impurities" of other,
more radioactive isotopes.  According to the WWW periodic table of
the elements (see http://cst.lanl.gov/CST/imagemap/periodic/92.html)
at Los Alamos -- folks who ought to know about this stuff! -- nearly
99.3% of natually occuring uranium consists of this isotope.  While
still radioactive, it has a half-life of 4.51e9, making it far less
active than the rarer isotopes.  In fact, it was probably depleted
uranium (a waste product from producing enriched uranium fuels or
weapons-grade uranium), with an even higher percentage of 238U.

>- Did CV990 fly during their whole (and short) life with these
>counterweights or were they quikly replaced ?

Why would they have been replaced?

>- Are there other examples where radioactive materials are employed in
>civil a/c ?

Most elements have radioactive isotopes or contain trace amounts of
radioactive elements, so just about everything in an airliner is
slightly radioactive.  238U might not be much worse than more common
materials given its long half-life.

The only thing I can think of that is *chosen* for its radioactivity
is the radioisotope commonly used in smoke detectors.  I assume the
ones in lavatories on airliners are based on the same design.

--
Karl Swartz	|Home	kls@chicago.com
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