Re:gauges on the grounds?

[Mike Bohan <mike.bohan@yale.edu>]

Hello RadSafers & David,

I had an experience with an industrial radiography operation a few years ago
at my hospital.

I was decontaminating an Iodine-131 therapy room located on the 9th floor of
the Hospital.  I was counting my wipe tests with a portable wipe test counter.
 I was concerned because I was getting "positive" results from areas which
were completely covered with Herculite during the therapy.  Consequently, I
recounted my wipes to make sure and they were magically "negative".  

I resumed counting and again started to get "positive" results.  I thought
that maybe I might be seeing some counts from a nearby patient which may have
had a diagnostic nuclear medicine exam.  I used a LEG probe to survey the room
and went down the corridor, but could find no spurious source for the
radiation.  I went back to the room and noticed an increased background which
grew as I reached the window.  I was looking out the window and entertaining
crazy thoughts like maybe I'm getting scanned by the Starship Enterprise when
I glanced down 9 floors to see a couple of guys wearing hard hats climbing out
of a pit in front of the hospital.

I immediately went down to the front of the hospital and saw one of the men
carrying an ion chamber.  I introduced myself and asked them what source they
were using.  They told me that they were using their "little" source because
of the close surroundings.  Their little source was 20 Curies of Ir-192, the
"big" one was about 100 Curies.  I told them I was picking up their source on
the ninth floor of the hospital which they found hard to believe.

The hospital was in the midst of constructing a new wing and were running new
steam lines to heat the new building.  The radiography crew were testing the
welds on the steam lines.  I found out that the steam lines were going through
the main hospital building and directly under my emergency x-ray dark room. 
They were going to test the lines through this area, so as a precaution, I had
the film supply in the dark room moved during the testing phase.

In observing their operation, they did a good job setting up an exclusion
zone.  I was amazed how hard it was to keep bystanders out of the controlled
area.  Many people wanting to take a short cut would attempt to cross the
exclusion zone barriers and had to be verbally chased out during testing.  In
the building, they shielded the source somewhat to reduce exposures to the
floors above.  All in all, it was an interesting experience, but I told them
that if they work on other hospital projects they should locate the RSO and
give them a heads up.  The RSO needs to know about these operations in case
they might cause some conflicts or confusion

As for the regulatory issues, they have their own license and their operations
are limited by their license conditions.  You would not need to modify the
university's license to cover their operations, nor would the university be
liable to the NRC for any event caused by their operations.

Regards,

Mike Bohan
Radiation Safety Officer
Yale-New Haven Hospital
Radiological Physics
20 York St. - WWW 204
New Haven, CT   06504
mike.bohan@yale.edu
TEL (203)688-2950
FAX (203)737-4252
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