re: ionization chambers, micro rem meters, etc.

[Keith Welch <welch@CEBAF.GOV>]

At 05:14 PM 11/14/96 -0600, you wrote:
>> What kind of operations involving radionuclides could result in a
> need to monitor beta dose rates and would not already limit access to
> the area by non-radiation workers due to contamination concerns?
> Maybe I spent too much time in the nuclear power community, but I
> couldn't think of anything. If there is, I would appreciate a reply<
>
>Your assumption is correct, as I see it. Considering the SDE 
>regulatory limit of 50 rem/yr, there really exists no occasion for 
>this scenario to be true. Even considering 100% inhalation of all 
>contaminants .. it just isn't possible.. If this isn't the case, I 
>too would be interested in probable scenarios where this concern is 
>valid.
>
>Sandy Perle

I don't want to speak for Jennifer on this, but I didn't interpret her post
that way at all.  She said, " I need to be able to assess accurately fields
as low as 2.5 microsieverts/h (0.25 mrem/h).  The radionuclides we work with
are low energy gamma/x-ray emitters, a wide range of energies of beta
emitters and some higher energy gamma emitters."  so it looks to me like she
needs to measure down to a level where she can make sure she is correctly
restricting access.  She did not say she was limiting access based on beta
exposure.  To take Richard's argument to an extreme we could ask why
contamination monitoring is needed in a nuclear plant when we already
control access based on external dose rates.

Looks pretty simple to me - she's got beta emitters, she wants to measure
them - she's not saying that they are the limiting exposure pathway.  Don't
the regulations say something about characterizing the radiation environment?


Just my two-cents worth.
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@cebaf.gov