Re: magnesium-zirconium-thorium alloys

[Joel Baumbaugh <baumbaug@nosc.mil>]

	Susan,

	While I am "certainly" no expert, I have been affiliated with quite a
number of waste sites which contain aircraft "parts" of magnesium/thorium
alloys.  To this date, (in Southern California soils), none of the aircraft
parts which have been unearthed have been found to constitute a groundwater
hazard.  One reason for this (as I have been told), is that the metal forms
a hard oxide (rust if you will) which forms on the outer surface of the
metal  retarding further oxidization and subsequent dispersion into the
surrounding soil.  While the objects ARE radioactive, the external dose
rates are quite low (especially when buried) - and are certainly not a
hazard for casual handling, although I ALWAYS wear gloves for prudence sake.  

	I have found however that the radium-painted (and sometimes Sr-90)
surfaces of many objects (not just dials) buried with the aircraft have a
greater potential for soil dispersion and therefore groundwater and human
contamination.

	The good thing here is that (in my experience) the Navy has recently gone
to GREAT LENGTHS to remove any and all radioactive material (for reburial
in "properly" monitored facilities) that it finds/has found, and that it
feels has ANY potential to harm the environment. 

	No, I'm not trying to get a raise here... As we all know, the pendulum
often swings from one extreme to the other.  In the past, these sources
weren't considered a problem.  Now the government (at least the Navy) is
spending BIG bucks to clean up its past.

	Of course, this is all just my own PERSONAL opinion,


	Joel Baumbaugh (baumbaug@nosc.mil)

..


At 01:13 PM 1/8/99 -0600, you wrote:
>Several years ago my husband (an environmental consultant with
>radchemistry training) managed a removal action at the Metcoa Superfund
>site (in NJ, I think).  The contaminant of concern was thorium,
>apparently from the recycling of aircraft components.
>
>I've often wondered how many Superfund sites have undiscovered
>radioactive contamination because EPA (or the state environmental
>agency) doesn't screen or sample for it.  In my opinion, this is a
>potential exposure problem for site workers.  For example, I have a
>friend who worked as a field chemist at the Mare Island Naval Base
>landfill site who later learned that there might have been radioactive
>contamination in the landfill.
>
>Does anyone have experience or thoughts on this matter?
>
>Regards,
>Susan Gawarecki
>--
>==================================================
>Susan L. Gawarecki, Ph.D., Executive Director
>Oak Ridge Reservation Local Oversight Committee, Inc.
>136 South Illinois Avenue, Suite 208
>Oak Ridge, Tennessee  37830
>Phone (423) 483-1333; Fax (423) 482-6572; E-mail loc@icx.net
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