Irradiation damage from alphas to plastics Frm (Re:Pu contact dose)

[Kerimbaev <kerrembaev@yahoo.com>]

Doug,



1. Have you looked at "H-3 water in contact with

plastic materials" studies?

There were similar phenomenas.



Low energy electrons and high energy alphas

should/would-? have similar penetrating

properties.



2. Flux x time (particles/cm^2 * sec) v.s damage

depending relationship would be more convenient

than a contact dose(RADs/GREYs) v.s. damage. 



3. Again, to conduct material science studies you

CAN NOT avoid experimental portion of it.

(MCNP fans excuse my point of view)



4. Irradiation of plastic materials with low

energy electrons (electron accelerator) could be

a very close simulation of the penetration

process, then you will need to get correction

factors to account for the difference in LET's.



5. Simulation with UV light could be another

alternative.



Regards,





Emil.







You wrote:



>>>....

solid material.  While the damage mechanisms from

photons and neutrons have

been well studied, the surface damage from alphas

are much less well known.

This is important when the material is being used

as a sealing surface, such

as polymers used as valve seats.  DOE experienced

a significant Pu-238

release and subsequent worker uptakes at one of

our facilities a couple

years ago, partially due to failure of a valve

seat, and I have the task of

recommending an approach for how we will deal

with these applications in the

future.  I would be happy to forward you a copy

of the accident

investigation report, as it may be of interest to

you and others.



As it turns out, current research indicates that

the damage mechanism is

much different for alphas than for penetrating

radiations, and we are still

trying to evaluate the significance of that fact

for our facilities.  I can

readily calculate the alpha dose rates

(technically, what I am looking for

is the energy-deposition rate from alphas in

various plastics), but I was

hoping to find a published method or results that

I can compare my results

against, to provide a technical basis for a

future DOE standard on this



Doug Minnema, 

>>>>>









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