RE: Posting of "Beta" Radiation Areas

["Redmond, Randy R. (RXQ) " <RXQ@ornl.gov>]

DOE has stated in G-10 CFR 835/C2 - Rev. 1, External Dosimetry Program  (I
did not check the latest revision), for beta particles with maximum energies
less than about 3.5 MeV, the dose limit to the skin [50 rem] is more
restrictive than that for the lens of the eye.  At higher energies, the lens
of the eye dose limit dominates.  Therefore,, at beta energies below 3.5
MeV, if it can be shown that skin monitoring is not required then it follows
that lens of the eye monitoring is also not required."  Reference is ICRU
Report No. 43.

Randy Redmond
Lockheed Martin Energy Systems
P.O. Box 2009
Bldg.  9769,  MS 8081
Oak Ridge, TN  37831-8081
Email:  rxq@cosmail3.ctd.ornl.gov
Phone:  423-574-5640
Fax:  423-576-6047


	-----Original Message-----
	From:	Sandy Perle [SMTP:sandyfl@earthlink.net]
	Sent:	Friday, September 10, 1999 10:45 AM
	To:	Multiple recipients of list
	Subject:	Re: Posting of "Beta" Radiation Areas

	Ray Weedon stated the following:

	> Beta dose could be considered a risk issue for DDE for the eyes.
In most
	> power plants, workers typically wear safety glasses or other types
of eye
	> protection which provide sufficient shielding that DDE to the eyes
is not of
	> concern. 

	While the question concerns posting requirements, the issue of 
	potential risk should be addressed, as stated by Ray above. For
there 
	to be a risk from beta exposure to penetrate the cornea and lens of 
	the eye, the beta energy has to be very high. Per 10 CFR 20, the LDE

	dose limit is 15 rem/yr at a depth of 0.3 cm. In a study conducted
at 
	FPL years ago, we determined that 95% of all beta dose found from 
	normal plant work around valves and other beta source components was

	attenuated by 70 mg/cm^3. While I am not positive, I believe that
the 
	thickness of the lens of the eye exceeds this value.

	In my opinion, it is a rare occurrence where the eye becomes a 
	critical entity when working around beta sources, unless the energy 
	is high enough to not only penetrate the 0.3 cm, but also 1 cm.

	Sandy Perle
	E-Mail: sandyfl@earthlink.net 
	Personal Website: http://www.geocities.com/capecanaveral/1205

	"The object of opening the mind, as of opening 
	the mouth, is to close it again on something solid"
	              - G. K. Chesterton -
	
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