Appendix J Routine & Preventative Maintenance – Standard Models
358
Testing for Alarms
A regular check of the ALARM TEST system should be performed using a source
with activity near the release limit for the Alarm Set Point. Insert the small key into
the Alarm Test key switch and switch from NORMAL to ALARM TEST. The switch
is located on the outside frame on the GEM-5 (e.g. see photo in Figure 6 on page 11).
The key cannot be removed in the ALARM TEST position. The monitor will begin
counting down to a Clean/Contaminated decision. There will be a pause when the
decision is displayed (the default is 2 seconds, set in the Wait Timeouts screen) and
then the countdown is repeated. Placing a source in front of any detector will cause a
contaminated decision and will verify that the detector is functional and the alarm set
points are correct.
When performing an Alarm Test on a foot detector when Count Gamma Body In
Two Steps is set to “YES”, the check source should be left on the detector for two
counting periods. If the result is “CLEAN” on the first count, this should be ignored.
At the completion of the test, return the key switch to the NORMAL position and
remove the key from the lock. It is not necessary to test every detector every day, but
a random check of a few detectors takes only a few seconds. Housekeeping staff that
perform daily cleaning could do this test, or regular service maintenance or radiation
control personnel could perform it. Report any discrepancy to the appropriate group
or authority for early corrective action.
The Alarm Test mode is described more fully in the previous Chapters.
Repair of Detectors
Handle detectors carefully at all times, even if the detector has failed. No refund will
be given for any detector exhibiting physical damage, no matter what the failure
cause.
If Mirion Technologies (Canberra CA) Ltd. is to repair a d
amaged detector, contact your
local Mirion Technologies (Canberra CA) Ltd. affiliate to obtain a returned authorization
number and shipping information prior to returning a detector.
Proper operation of gamma scintillation detectors requires a 100% opaque envelope
surrounding the detector and photomultiplier tube. Any leakage of light will cause
the detector to malfunction. The plastic scintillation detectors have no life limiting
mechanisms other than physical damage such as breakage. Most failures are caused
by a damaged light seal. A failed photomultiplier tube or detector board will also
cause the detector to malfunction.
If repair to the light envelope or the photomultiplier tube cannot be accomplished by
the owner, detectors can be returned
to Mirion Technologies (Canberra CA) Ltd. for
repair or exchange. Contact your local Mirion Technologies (Canberra CA) Ltd.
affiliate to obtain a returned authorization number and shipping information prior to
returning a detector.
To Next Page
Loading...
Need help?
General
