Chapter 5 Parameters Definition
120
Alarm Test Source Dimension/Date: This is the same item as described in the
F5 – Group Settings screen on page 127 but applies to the selected zone only. This
item is used to convert Alarm Test Source activity values expressed in Bq/cm² (or
dpm/cm² or nCi/cm² or pCi/cm² or µCi/cm
2
) to Bq (or dpm or nCi or pCi or µCi as
appropriate). It only appears if a “…/cm²” unit is chosen in the Activity Units setting
in the F1 – Common Values screen on page 103. It is shown here for information, but
set in the F9 – Edit Calibration Source List screen on page 137.
The Date is automatically filled in based on the Source.
Expected Net Rate is also shown for Alarm Test Source. It is obtained by decay
correcting alarm test source activity and multiplying by percent of source visible and
current detector efficiency
Verification Test Extra Time: This setting is only shown when a “Verification
Test” is set as the Alarm Test Type. It allows extra time for positioning source for
specific detectors such a hand detector or first detector using a different source. The
next three items on this screen relate to background count rate alarm settings and
apply only to single detection zones.
When viewing individual Gamma detectors, the following are shown (also applies to
Gamma groups in F5 – Group Settings Gamma screen on page 127 for Gamma
groups):
High Background Rate
5
: This is the same item as described in the F5 – Group
Settings screen on page 127 but applies to the selected zone only. It defines the level
abovewhich the monitor should not be operated (i.e., the level above which it is
expected that interference from the background will prevent the release limit from
being measured with the required confidence of alarm K Beta). The resulting action
is determined in the F4 – Out of Service Causes screen (for example, a setting of
AUTO, any detection zone that exceeds this count rate during a background update
will generate a High Count Time Fault. An indication of an appropriate setting may
be obtained from the F4 – Monitor Time vs. Bkg Rate graph in the F5 – Information
Menu. The factory defaults for non-frisker detectors are 60 cps for Alpha channel,
200 cps for Beta channel, 600 cps for small Gamma detectors (shoe & head) and
1800 cps for large Gamma detectors (full body). This setting will flag high
background rate when the required monitoring time exceeds the Maximum Monitor
Time (set in the F2 – Wait Timeouts screen.
The range is 1 to 16600 cps; default 1800 cps.
Excessive Background Rate
5
: This is the same item as described in the F5 – Group
Settings screen on page 127 but applies to the selected zone only. The factory default
setting is 15000 cps. This is the count rate considered to be beyond the accurate
counting capability of the electronics. This rate would indicate a component
malfunction or an exceedingly high background. The action to be taken when this
level is exceeded is defined in the F4 – Out of Service Causes screen.
The range is 10 to 16600 cps; default 15000 cps.
5
High Background Rate, Excessive Background Rate, and Low Background Rate settings apply to single detection zones
only, not sum zones.
To Next Page
Loading...
Need help?
General
