Using a Survey Meter

Radiation Survey Meter – Description and Use

Purpose and limitations

• Used to detect moderate‑ to high‑energy beta, gamma, and X‑ray radiation
• Cannot detect low‑energy beta emitters, such as tritium (H‑3)
• Not appropriate for measuring tritium contamination

Components

• Probe – detects radiation
• Base unit – houses electronics
• Meter face/readout – displays measurements

Pre‑use checks

Before using a radiation survey meter, ensure the following:

Calibration and compliance

• Verify the presence of a valid calibration sticker
  • The CNSC requires annual calibration for meters used for dose‑rate measurements (e.g., mR/hr or mSv/hr)
• Note:
  • Instruments that read in counts per minute (cpm) or counts per second (cps) are considered contamination meters
  • These instruments cannot be calibrated and are instead verified annually for proper operation

Instrument suitability

• Confirm the probe is appropriate for the radioisotope being used
• If uncertain, contact the Radiation Safety Officergurnam.manku [at] affiliate.mcgill.ca ( (RSO))

Equipment condition

• Ensure all cable connections are secure
  • Loose connections may damage the instrument
• Perform a battery check

Operating the survey meter

• Set the scale to the lowest multiplication range
• Turn on the audio function
• If the instrument has an F/S switch, ensure it is set to “F”
• Allow the meter to warm up for 15–20 seconds
• Measure and note the background radiation level
  • Perform this step away from radioactive sources

Surveying for contamination

• Hold the probe as close as possible to the surface without touching it
• Use the audio signal to help locate contamination
• Identify and record the highest count rate (cpm)
• Assess the extent of contamination
• Perform a wipe test to determine whether contamination is removable

After use

• Turn off the survey meter once monitoring is complete

Interpreting survey meter readings

When using an end window or pancake probe:

Converting radiation meter readings

Units	Meter Readings
cps	0	2.5	5.0	7.5	10.0	12.5
mR/hr	0	0.1	0.2	0.3	0.4	0.5
µS/hr	0	1	2	3	4	5

To convert to cpm: cps x 60 = cpm