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Re: A couple off-the-wall (unrelated) questions
Dear Jim,
X-Ray Diffraction Dosimetry
I am currently making a number of changes here in the University of Bristol, UK in just this area. Where our apparatus
is used in a safe configuration (where the system is interlocked and dose rate outside the enclosure less than a
supervised area), I do not issue dosimetry. For those who need to over-ride interlocks and work with even the
potential of a beam (due to some failure of the system) I issue dosimetry. Modern equipment is not our big problem.
We had apparatus from PRE-WAR (I finally got that junked about a year ago) and it takes a lot of work to get some
of the older sets to a reasonable level of safety. We are setting up a hierachical structure, where an experienced and
competant user is responsible for each set and then arranges that proper training is given to allow others to rise up
through the system and be allowed to perform increasingly high level work.
All our sets are being boxed in (those in regular use already are - the difficulty is those which are "out of use" until
someone needs another set) or disabled and trapped key over-ride systems added where they were not original
equipment or part of the upgrade. With some of the oldest sets we have difficulties with adequate control of the
shutter position and are working on this (our major problem is finding the finances to upgrade to better apparatus).
I strongly advise the use of radiation monitors but beware of the energy of the X-rays. I have recently been sent a
study from the National Radiological Protection Board here which demonstrates that leaks of radiation from analytical
sets tend to be mostly of the characteristic X-rays. We've had problems here with the fact that the normal monitoring
sets (end window GM) simply are not sensitive to low energy leakage beams which have been detected by thin crystal
NaI PM systems. The problem is that these are notorious for losing their calibration........
I don't think what we are required to do in the UK is directly helpful to you as it has been forcibly drawn to my
attention that the way rules are operated on the two sides of the Atlantic are rather different in emphasis, but I hope
this comment from a fellow sufferer will be of some assistance in rounding out ideas.
David Walland
University of Bristol (UK)
Radiation Safety Officer
On Fri, 20 Oct 95 15:41:50 -0500 Jim F. Herrold wrote:
> From: Jim F. Herrold <HERROLD@UWYO.EDU>
> Date: Fri, 20 Oct 95 15:41:50 -0500
> Subject: A couple off-the-wall (unrelated) questions
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
>
> Hello out there in RadSafe land...
>
> I have a couple things which are puzzling me on this Friday afternoon an dwould
> appreciate some insight. These are two ares in which I am sadly ignorant, so
> any answer, no matter how basic it may seem, is probably not too basic for me.
>
> #1. What recommendations do other research institutions follow for monitoring
> technicians in x-ray diffraction labs. We have a couple units on campus made by
> Scintag (an XDS2000 and a PADII), which are fully enclosed and shielded, so
> that exposures to all users have been less than detectable. In fact, the area
> monitors do not even register any exposures. Now, before you go telling me to
> talk to my state regulatory agency, you should know that here in Wyoming we
> don't HAVE one. It was eliminated three years back and no one over there at the
> Capital has a clue. What I am looking for, then, is the accepted guidelines in
> OTHER states who still care about x-ray safety. I've been meaning to go get
> some exposure levels with a portable PIC (as soon as I get a round TUIT). Based
> on that information, I'm inclined to leave the area monitors there but stop
> badging the people individually. Following the NRC guidelines (my only source
> of inspiration on radiation protection) I would say monitoring of individuals
> is not required. Feedback, please.
>
> #2. Can pancake geiger detectors be set off by high electromagnetic fields?
> Yesterday one of our techs was out surveying a lab and thought he had a short
> in his cable because the meter pegged as soon as it was turned on. He went back
> to get another geiger counter and the same thing happened in the same lab, but
> only near a bench with a number of lab instruments running on it. There was no
> radioactive contamination, it seemed to just be from the instruments themselves
> (a compressor, water bath and speed-vac). Excuse my ignorance, but is this a
> radiofrequency thing, or EMF? Should the electricians look at the wiring in the
> lab? Could there be a problem? It sure made it hard to do contamination
> surveys when just about anything electrical set off the GM detector.
>
> Have a nice weekend.
>
> Jim F. Herrold, RSO U U W W University of Wyoming
> e-mail: herrold@uwyo.edu U U W W W Environmental Health & Safety
> phone: (307) 766-3277 U U W W W W 312 Merica Hall
> fax: (307) 766-2255 UUUUUU W W Laramie, Wyoming 82071-3413
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> "Opinions are my own and do not represent those of the University of Wyoming,
> or anyone else for that matter. All mistakes are the fault of the computer."
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