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6 Radiation Protection Volume 1
6.3.4 Testing the Shutter Mechanism
This procedure ensures that the shutter mechanism is operating
correctly and that the shutter is closed and the source is completely
shielded when CLOSED is indicated by the device handle or cylin-
der. This is very important to avoid exposures to radiation if for
some reason (such as a broken shaft in a point source shielding)
the shutter indication is CLOSED but the shutter remains open. The
USNRC and Agreement States make this a mandatory test to be
done at intervals not to exceed 6 months. You may be asked to
provide documentation of previously performed tests and a sched-
ule for the next set of tests on your devices.
Make sure that the process engineer is aware that process
information will be interrupted during the test.
Determine the count rate (via the HART
®
Communicator or
SIMATIC PDM).
Write down the reading.
Move the shutter to the CLOSED position and observe reduction
of displayed counts to zero or to a very low background level.
Write down the reading.
Repeat the sequence 5 times, noting the readings each time.
Ensure that the shutter moves freely, without binding or stick-
ing.
If all is well, disconnect the HART
®
Communicator or terminate
the SIMATIC PDM and report the result to the process engineer.
If there is a failure or you have doubt, notify the BERTHOLD
TECHNOLOGIES service department.
Document the test, including the date of test, the device model
and serial number, test conclusions and your name. A govern-
ment inspector may ask you for this information.
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