GR-100 User's Manual Revision 1.2
2.0 Operation
NOTE
: In normal background conditions (absence of radiation sources), the count rate should be
between 5 and 25 cps and the dose rate about 50 - 250 nGy/h, 50 - 250 nSv/h or 5 - 25 mR/h.
The battery status icon is fully black when battery is fully charged. As the battery capacity goes down
the black filling decreases to the right-hand side. The icon is “empty” if the capacity drops down to
about 10 %.
The YELLOW LED light flashes faintly every three seconds to show the system is operational and battery
is OK. If battery is low, the RED LED light starts flashing.
2.7 Dose rate
The GR-100 is an instrument that accurately displays the computed Dose-Rate over the full spectrum
range. The unit is calibrated so that whether the source is Americium, Cesium, Cobalt or any other
isotope, the Dose Rate computation is accurate. This is achieved by using an internal spectrometer
analysis system that compensates for spectral influence of the Dose Rate. The Dose Rate is shown in
both Monitor and Search modes in the bottom part of the display.
Note
: The displayed Dose Rate is a 10 second moving average. It means that the value is renewed
every second, but it is calculated from the signal measured during the last 10 seconds.
Current Dose Rate can be measured in three different units:
•
Gy/hr (Grays per hour) units are used mostly in Europe for radiation Dose Rate measurements.
•
R/hr (Roentgens per hour) units of exposure to radiation are used mostly in North America.
•
Sv/hr (Sievert per hour) units are used for equivalent Dose Rate when the person’s health risk is
assessed.
The measurement range is 0.01 – 100 µSv/hr, covering the range from very low background to the
danger level. When the actual dose rate is higher than 100 µSv/hr, the message OVERLOADED is
displayed instead of the dose rate value. The display returns to show the dose rate when radiation level
drops below 100 µSv/hr.
The calibration point for dose rate is defined as the center of the gamma detector, which is 3 cm from
the top edge of the unit (in the middle of display), 1 cm from the right edge and 1.3 cm under the face
side. The irradiation direction is from the side opposite the display.
The Dose Rate is accumulated in the GR-100 memory during operation in Monitoring or Searching mode
and stored every hour, or when the unit is powered down. The results can be downloaded to a PC and
saved. The Dose Rates are always stored in nSv/h units no matter what selected units are set for
viewing on the display.
SAIC/Exploranium – Proprietary
Page 7
Revision Date:
November 2004
Summary of Contents for GR-100
Page 14: ......