Re: Industrial radiography and computers

["Mike Malaxos" <rss@arach.net.au>]

I do not know of any permanent effects on semiconductor junctions or
magnetic material caused by the sort of dose rates likely to be experienced
during the tests. My assumptions are based on the following:

1.  Dose rate from 65 Ci Ir 192  about 32 RAD /h. Dose rate at 12 m about
220 mRAD/h.

2  The beam should be limited with a collimator. The above dose rate should
only be in the useful direction This dose rate would be attenuated by the
floor (the part under examination).

I would imagine that dose rate 2 or 3 orders of magnitude higher would may
be necessary to see an obvious change in a germanium reversed biased
junction.

In summary if computers within 3 m of the exposed source were turned off (
which may be an unnecessary precaution) I would be surprised if any effects
whatsoever would be detected.




Best Regards
M.Malaxos
Radiation Safety Services
69-71 Robinson Avenue Belmont
Western Australia.  6104 
Fax 61 89 475 0165
P 61 89 475 0099  a/h 089 255 1214
email rss@arach.net.au
 

----------
> From: Ken Smith <ksmith@cats.ucsc.edu>
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject: Industrial radiography and computers
> Date: Saturday, 7 March 1998 1:10
> 
> Hi All - 
> 
> We are going to have a number of exposures taken of floors and walls in
one
> of our science buildings.  The purpose of the radiography is to determine
> the location of cables in the post-tension cement beams, to avoid them
> during a drilling operation.  We are contracting a local firm to perform
> the radiography. 
> 
> There has been some mention of removing any computer CPU's and magnetic
> storage devices (disk drives) in the near (40 ft') vicinity of the
exposures.
> 
> Do you know of any references that I can research?
> Has anyone personally experienced problems with computer storage loss by
> radiography exposures?
> 
> (The source that will be used is a ~65 Curie Ir-192 source)
> 
> Thanks in advance for any responses - please reply to my e-mail below
> unless you thing it interesting to the entire list.
> 
> ----------
> Ken Smith
> Acting Radiation Safety Officer
> University of California
> Santa Cruz, CA  95064                   
> Voice: (408) 459-3911
> Fax: (408) 459-3209
> e-mail: ksmith@cats.ucsc.edu 
>