Ludlum Measurements 52-1, Manual

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Model 52-1 Family Technical Manual
Section 3
Ludlum Measurements, Inc. Page 3-3 July 2018
Operational Check
To ensure that these instruments are functioning correctly, an operational
check should be performed routinely or before using the instrument. This
check verifies that the instrument is turned on, that the settings are
appropriate, and that the system alarms when the detectors are exposed to
excess radiation (above background level). Ludlum Measurements suggests
that this operational check be performed after setup and before use. As long
as the system passes the operational check, no calibration or other checks are
necessary. If the response or any function of the portal monitor changes,
the instrument should be checked and brought into compliance with the
manufacturer’s original specifications.
Check each of the detectors for sensitivity to beta/gamma radiation. Verify
that you get a RADIATION ALARM, using the check source supplied with
the instrument (normally a
137
Cs, 1
µ
Ci or 37.5 kBq activity source.
In walk-through mode, simply walk through the portal, holding the source in
proximity to a detector. This action should cause the portal to enter the
RADIATION ALARM status until the alarm time parameter is complete.
In stop-and-count mode, you should stand in the portal for the duration of
the count time. At the end of the count time, the portal should enter the
RADIATION ALARM status until the alarm time parameter is complete.
Repeat alarm checks for all four sections to confirm that all detectors are
functioning.
To also provide assurance that the instrument meets the FEMA emergency
response criteria prior to operation of this portal, do the following: Pass the
1 µCi (37.5 kBq)
137
Cs checksource through the center of the portal at several
points between 15.2 and 168 cm (0.5 and 5.5 ft) from the floor of the portal
and verify that the alarm is triggered each time. If the portal does not alarm
each time, the user may need to adjust the count time, the alarmpoints, or
move the portal to a location with lower background radiation.
Personnel Monitoring
A count starts when someone blocks the infrared beam. A count can
only be started when the system is in the
ENTER mode. Do not enter
the portal while the yellow UPDATING status LED is flashing.
Prior to personnel monitoring, the monitor must be allowed to update the
background count. This mandatory update occurs just after power-up, and
takes one minute. New background data is compared to the low and high