S.E. International Radiation alert Monitor 1000 EC Operation Manual - page 11
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Chapter 4: Common Procedures
The following sections give instructions for several commonly-used procedures. With any procedure, the user
must determine the suitability of the instrument or procedure for that application.
Establishing the Background Count
Normal background radiation levels vary at different locations, different times, even in different areas of
the same room. To accurately interpret the readings you get, it is good to establish the normal background
radiation count rate for each area you plan to monitor. You can do this by taking a timed count. See Chapter 3:
How To Take A Timed Count.
A 10-minute average is moderately accurate. You can repeat it several times and compare the results to
establish accuracy. To establish a more accurate average, take a 1 hour timed count. If you need to determine
whether there is prior contamination, take averages in several locations, and compare the averages.
Environmental Area Monitoring
You can keep the Monitor 1000
EC
in dose/rate mode whenever you want to monitor the ambient radiation, and
look at it from time to time to check for elevated readings.
If you suspect an increase in ambient radiation, use the count mode and take a 5 or 10 minute count, and
compare the average to your average background count. If you suspect an increase that is too small to detect
with a short timed reading, you can take a longer count (for example 6, 12, or 24 hours).
Checking for Surface Contamination
To check a surface, hold the detector window close to the surface, and read the count rate (wait 30 seconds
or until the reading has stabilized). Do not touch the unit to whatever you are checking to avoid contaminating
the unit.