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Re: Plastic and radiation damage

At 10:01 AM 4/23/1998 -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

Depending on the type of plastic and total dose, the plastic can discolor,
become brittle and crack (especially if it is under stress).  Many
non-conducting plastics can also build up charge too (ever seen those
electron "trees" formed in Plexiglass, which are created by electron
irradiation (LINAC), followed by tapping a grounded nail into the edge of
the Plexiglass sheet?).  For many common plastics, the onset of visible (to
the naked eye) structural damage usually requires a substantial total dose,
typically in the range of hundreds of kilorad to the tens of megarads.

The more important question to ascertain is, therefore, what is the total
dose that you expect the plastic container to receive?

You can find data on the correlation of damage in materials (including
plastics) versus total dose in the open literature and books on radiation
effects on materials.

Hope this helps!

Gary Pepper
Radiation Physics Consultant

Ottawa, Ontario, Canada
e-mail:  gpepper@capitalnet.com