Radiation safety

Geiger Müller Counters

Geiger Müller (GM) counters provide effective detection of X-rays, gamma and beta radiation. There are two types of GM counters, which serve different purposes: Survey Meters and Contamination Meters.

Survey Meters are primarily used to conduct area surveying whereas Contamination Meters are used in the detection of radioactive contamination. The Canadian Nuclear Safety Commission (CNSC) requires that survey meters be calibrated every 12 months, and each time the probe is changed or broken. There are no calibration requirements for contamination meters, however it is recommended that they are checked periodically. A copy of the calibration reports are kept on file in the Hot Lab.

Meter applications:

When to use a survey meter (mR/hr or uSv/hr readout):

• Monitoring TDG 7 packages
• Conducting area monitoring

 When to use a contamination meter (CPS or CPM readout):

• Detecting personal contamination
• Detecting contamination of work area and materials
  

Important: Always perform a battery check prior to using any GM Counter.

For detailed instructions on how to use a GM counter, please watch the Proper Use of a Geiger Counter video, created by Northwestern University, and see the How to use a GM Counter booklet.

Liquid Scintillation Counters

Liquid Scintillation Counters (LSCs) are used to measure ionizing radiation. LSCs provide effective detection for lower energy radiation. Radiation Safety staff conduct monthly calibrations and background checks of the instrumentation in the Hot Lab facility.  Staff also conduct annual calibrations and background checks on instrumentation in research facilities. Copies of all calibration records and background checks are kept on file by the Radiation Safety Technician.

When survey meters are not applicable, detection of contamination from lower energy radiation is conducted by measuring wipe tests in the LSC. Before counting samples in the LSC, liquid scintillation cocktail that is added. The ionizing radiation interacts with the cocktail and produces light, the device then measures the generated light of each sample to determine the amount of radioactivity.

For information on the use of LSC instrumentation, please watch the SFU LSC Training Video and see the Mandatory Checklist and LSC Logbook.

Note: LSC users are urged to follow the mandatory checklist to avoid damage and costly repairs to the instrumentation.

Gamma Counters

Gamma counters are used in the detection of radioisotopes emitting gamma radiation. The scintillation detector holds a sodium iodide crystal and upon interaction with gamma radiation light is being emitted and interacts with a photomultiplier tube (PMT). The intensity of the light is proportional to the energy of the measured radiation.

Counter applications:

• Counting gamma radiation emitting samples
  
• Thyroid bioassay

SFU participates in an annual Thyroid Performance Test in collaboration with Health Canada to ensure proper functionality of the Gamma Counter for thyroid bioassays. A copy of the performance test results and certificate must be kept on file with the Radiation Safety Officer.

Note: If you are working with Radioiodine, contact the Radiation Safety staff. For more information, please refer to Dosimetry– Internal Exposure Monitoring.

Neutron Generator

Neutron generators are neutron source devices which contain compact linear particle accelerators which produce neutrons by fusing isotopes of hydrogen.

The Nuclear Science Laboratory (NSL) at SFU includes the operation of a Neutron Generator Facility (NGF). NSL provides required training and  access to a Thermo  Scientific  P-385 deuterium-tritium neutron generator  producing 14.2 MeV neutrons at a nominal rate of 3 x 10 E 8 neutrons/second as well as to a state-of-the-art gamma ray and light ion detectors.

The NSL represents a small operation and supports a research program which includes nuclear structure studies, develoment of techniques for radiation detection, production and separation of radioisotopes, neutron activation analysis and studies of environmental radioactivity.

For details, please contact:  Dr. K. Starosta, Chemistry Dept., email: starosta@sfu.ca