SAIC Exploranium – GR-135 System Manual page: 7
2.0 SYSTEM DESCRIPTION & FEATURES
This manual fully describes the MANUAL mode so full system functionality is covered
See Appendix A for AUTOMATIC mode operation
2.1 OPERATIONAL FUNCTIONS
The GR-135 may be operated in 2 Primary radiation monitoring functions.
a) SEARCH + DOSE mode
In this mode, the GR-135 acts as SEARCH Meter displaying the current COUNT RATE in
counts/sec. A variable-tone AUDIO will indicate radiation intensity with an automatic audio meter
or user adjusted alarm level. A “chart-record” of the last 100 data points is displayed on the
screen during the SEARCH. This mode is typically used to search for radioactive material or to
carry out Total-Count grid Search.
This mode also displays the current DOSE RATE (in selectable units and quantities) as well as
ACCUMULATED DOSE from the time the mode was enabled. The dose meter is used to
determine the relative hazard level and to assess handling requirements of a radioactive material.
Dose Search of an area can also be carried out in this mode
b) IDENTIFY mode – (Nuclide Identification)
In this mode, the GR-135 accumulates spectral data from a sample and analyses the spectrum in
terms of emitted energy level and net count contribution. The nuclides responsible for producing
the spectrum are identified by comparison to a nuclide library and presented in tabular form.
This essential information can then be used to determine risk assessment. If the optional CZT
detector is used the unit automatically decides on detector use as determined by the source
signature, so this is fully automatic.
2.2 SYSTEM FEATURES
a) INSTRUMENT BODY - The instrument body consists of 2 primary parts, the lower case and top
panel. The lower case is deep-formed aluminum that provides a strong basic structure. The top
panel is specially formed ABS plastic that minimizes weight while maintaining the ruggedness of
the unit. The combination of the two parts provides a high degree of system strength, suitable
for field operations where mechanical abuse may be unavoidable.
b) DETECTOR –
1- NaI - The 4.0 cu. in. (0.065L) Sodium-Iodide [NaI (Tl)] detector assembly is specially
designed for rugged environments. The NaI crystal is enclosed in a specially molded
rubber sleeve to give a high degree of mechanical protection against shock and is fully
enclosed within the instrument body.
2 - GM – the rugged GM tube is mounted just behind the instrument front face and is used
to extend the Dose Rate range to 1R+ for special applications
3 - NEUTRON – this detector is a solid-state non-gaseous detector with high sensitivity and
has no travel restrictions.
4 - CZT - this optional detector is used in special applications to improve the systems Nuclide
ID capability. CZT is a specialized detector with a resolution approx twice that of Sodium-
Iodide thus allowing discrimination of some peaks that are impossible to see on a NaI
detector.
c) HANDLE - The handle is a custom designed molded rubber part with a carefully designed
diameter and special indentations for fingers. The rubber type was selected to give a good
balance between strength and comfort.
To Next Page
Loading...