Unsafe High School Science Project

["William G. Nabor" <wgnabor@uci.edu>]

Dear RADSAFER's:

     Yesterday I and a fellow member of the Southern California
Chapter of The Health Physics Society helped judge the Orange
County, California, Science Fair, an exposition in which students
aged 11 to 17 display their science projects.  The Chapter offers
an award to the best project involving radiation.  In the past some
of the projects have been truly amazing and ingenious.  Others have
been less so.  This year we ran into one that was frightening,
presenting a clear and imminent safety hazard to the student,
possibly lethal.  We fully intend to communicate with the student's
teacher and the fair officials expressing our concern.  However we
wish neither to discourage the student or her teacher from further
participation in science nor to bring up the specter of big, bad
radiation.  Therefore, I would appreciate any advice any RADSAFEer
would care to give on how best to proceed.  Please address your
comments to WGNABOR@UCI.EDU rather that to the list in general, as
I don't suppose many RADSAFEers would be interested in such a rare
occurrence.

   The project was a home-made X-ray machine constructed by a 15
year-old high school student in the following manner:  The power
supply was a 12 volt DC 10 amp commercial automobile battery
charger, the output from which was connected to a vibrator.  No,
not that kind of vibrator.  This one was a voltage booster.  The
negative output lead from the vibrator was connected to the base of
an ordinary incandescent lightbulb.  The positive lead was
connected to the tip if the glass globe under several layers of
aluminum foil, uncalibrated eyeball estimate 1mm thick.  The
student _claimed_ that she used a "geiger counter" to measure the
output from this device and got a 300 to 1000 mR/hr dose rate.

   We immediately started asking questions about this geiger
counter to determine how likely was it that this reading was
correct.  Unfortunately, English was not her native language.  We
could not determine if the responses we got from the student
indicated her total unfamiliarity with the physics involved or of
English.  She could not describe the counter.  The photograph she
had of the device was out of focus and overexposed so we could not
tell what kind of device it was except that we had never seen a
geiger counter of this sort before.  It looked somewhat like a
Ludlum AC powered area monitor, but was certainly no Ludlum
product.  Neither was it an old civil defense survey meter that the
U.S. government passed out ad libitum after the end of the cold
war.  Some of these could read in the R/hr range.

   We attempted to get some indication of the output of the
vibrator, which was housed in a wooden box with no external
markings of any sort.  She appeared not to understand the term
amperage at all and continuously confused voltage with wavelength.
We could, therefore, not determine either the output voltage or the
amperage of the vibrator and so remain ignorant of these two
critical parameters.

   Our safety concerns are three:  First, the electrical safety, of
which there was none.  With the exception of the power cord to the
commercial battery charger every connection was bare.  Alligator
clips, aluminum foil, bare wires, even the connections to the
lightbulb and the 120 volt AC mains, all were fully exposed.  This
represents a potentially lethal and fully unacceptable situation
which we will communicate to the teacher.

   The second was a minor fire hazard as the lightbulb was tightly
taped to an unpainted pine two-by-four.

   It is the radiation hazard with which I am asking help from
RADSAFE.  I am requesting your opinions on the following:
   1)  Remembering that the target is thin glass and about 1mm of
Al, and that the positive lead is connected to the outside of the
glass globe, how likely do you think it that this device could
produce X-rays or beta rays?
   2)  If it can produce ionizing radiation, how likely is it that
it can produce 300 to 1000 mR/hr?  We were not about to suggest
that she turn it on in the exhibition hall so we could take
measurements!
   3)  How best can we word our communication so as to prevent such
a project in the future without discouraging others from interest
in radiation?

   Finally, no, we did not give this project an award.

   Thank you for your help.
**********************************************************************
William G. Nabor
University of California, Irvine
EH&S Office
Irvine, CA,  92697-2725
WGNABOR@UCI.EDU
mailto:wgnabor@uci.edu
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