Re: Working life of sealed industrial sources -Reply

[Jose Lopez <JLOPEZ@MEDNET.SWMED.EDU>]

I actually participated in the "witch hunt", but it was a little more
complicated and spread than it appears. The "air ionizers" made primarily
by the 3M Co. contained Po-210 impregnated into  ceramic microspheres.
Since the air ionization was to be effected by the alpha particles, the
spheres were laid in a glue type environment where half of the sphere
was exposed, the alpha particle could escape, and was allowed to
ionize the air.
 Most of the devices included instructions (in very small print) indicating
that they should be kept away from moisture because the humidity would
weaken the bond  allowing the potential  release of the ceramic beads.

The devices were extensively used ,from your local K-mart photo-shop
to your many beverage bottling Co. (Coke, Pepsi, 7-up, etc.), to your
semiconductor Co.etc . The devices were frequently used as "guns" in
compressed air lines (where the moisture traps frequently overflowed)
or in manufacturing lines to blow into bottles and cans to take the static
out of any airborne particle (The whole manufacturing line is steam
cleaned once or twice per day). The problem was first detected as
contamination in a bottle of acid of extreme purity needed in the
semiconductor industry. The manufacturer of the acid was using the air
ionizers inside an industrial size bottle washing machine where the dry
air alternated with hot water and steam to clean the bottles. 

It was an exhausting incident which spread alpha contamination into
many unsuspecting locals that had obtained the devices under a General
License and where their only instruction was to leak-test them at a 13
month interval or return them at yearly intervals to the manufacturer for
replacement. Obviously, the only information that the States and the NRC
had was a periodic list from  the 3M Co. indicating the distribution of the
devices. The great majority of users did not returned the air guns on
yearly intervals and did not leak-tested them at the 13 month interval.

Jose lopez, PhD, P.E.
jlopez@mednet.swmed.edu