Re: Plastic and radiation damage

[Joel Baumbaugh <baumbaug@nosc.mil>]

	I will reply to RadSafe in case this is of interest to others:

	Gary,

	I saw two excellent answers by Gary P. and Scott K. but I "think" that you are asking about what damage (if any) the Autoclavable Carboys (usually with Handles) made of polypropylene that you find at many/most universities might show from temporary or long term storage of radioisotopes (whew, what a long sentence).

	Having worked at various/sundry universities/facilities which utilize such carboys, I can definitely say that yes, damage does appear to occur from the radiation.  Carboys which only contain non-radioactive liquids (either low or high pH., lipids [aqueous or non-aqueous]) in my experience, very seldom fail to maintain their integrity even after years/decades of storage.  

	Carboys which are used to store radioactive liquids (H-3, C-14, S-35, Ca-45, P-32, P-33, Cr-51, Rb-86......) eventually DO fail...most often around the "seam lines" of the containers.  After quite a number of failures, both statically in storage and dynamically during movement of the containers, secondary containers of sufficient size to contain an adequate percentage of the carboy's contents were considered mandatory (say 25 - 50 percent of the carboy's volume).  Believe me, 10 - 15 liters of P-32 liquid in a lab is NO fun to clean up - it goes under refrigerators, centrifuges, lab benches, under floor tiles, out in the hallway etc.

	I have noticed that as they aged, the carboys would loose their smooth translucent appearance, become totally opaque, often turn a yellow-brown color and would even become brittle with (I saw once) chips occurring where they were struck against another hard object.  When they get ugly (a subjective evaluation I know) it is time to put them into the solid RADWASTE stream and get new ones...

	A carboy with multiple microcuries or millicuries (kBq - MBq) of radioactive material is being "exposed to" (pardon the pun) many, many interactions/second - 24 hours a day, 7 days a week..... That's a BIG potential for chemical/plastic bonding breaks, and break they do...

	I hope this helps,

	Joel

..

At 10:00 AM 4/23/98 -0500, you wrote:
>Does anyone out there know if plastic is subject to any structural
>decomposition as a reults of being exposed to moderate exposure rate
>fields?  For instance, a plastic container being used to hold several
>gallons of liquid containing beta-gamma emitters at concentrations up to 1
>Ci/L (thats 37 GBq/L for our European friends).
>
>
>=======================
>Gary L. Schroeder
>Brookhaven National Laboratory
>Environmental Protection Office
>gs1@bnl.gov
>
>

Joel T. Baumbaugh, MPH, MHP
baumbaug@nosc.mil
Radiation Safety Officer
SSC San Diego, CA


	NOTE:	The contents of this message have not been reviewed, nor approved by
the Federal Government, the U.S. Navy, my bosses or my wife...

	How times change - how everthing remains the same:

2000 B.C.     "Eat this root."
1000 A.D.     "That root is heathen.  Say this prayer."
1850 A.D.     "That prayer isn't medicine.  Drink this potion."
1940 A.D.     "That potion is snake oil.  Swallow this pill."
1985 A.D.     "That pill is ineffective.  Take this antibiotic."
2000 A.D.     "That anibiotic is ineffective.  Eat this root."