Requirements: The frequency of radiation contamination surveys depends on laboratory classification, as specified in your Radioisotope Use Authorization (RUA):
- Low-use lab – monthly
- High-use lab – weekly
- Greater than 10 millicurie (mCi) per experiment – daily or after each use
If you don't know your lab classification, contact the health physicist for your location.
Recommendation: Environment, Health & Safety (EH&S) recommends meter surveys before and after each use of radioactive materials.
The type of radioisotope involved and area to be surveyed determine whether you need to perform a direct or indirect survey. Read How to Perform a Radiation Survey for step-by-step instructions on both methods.
 Direct survey: Use a meter and probe to provide immediate indication of contamination. Perform direct meter surveys for all isotopes except tritium. In areas of locally high background readings, such as near or on the outside of a waste container, both a direct and indirect survey are required.
 Indirect survey: Use wipe tests for tritium use. You can substitute wipe tests for meter surveys in areas where meter monitoring is impractical (e.g., inside a microfuge) or where very small amounts of activity (less than one microcurie) are used.
Survey meters operate on the same basic principles but have varying capabilities and limitations, depending on the type of probe being used. Select the probe appropriate for the radioactive materials used in your lab.
- Geiger-Mueller probes detect beta-emitting radioisotopes. However, they can't detect H-3 and are poor at detecting radioisotopes that emit only photon radiation.
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- Scintillation probes detect gamma- (or X-ray-) emitting radioisotopes.
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See Additional Resources for Radiation Safety for vendors of survey instruments.
Need an expert? Contact EH&S Radiation Safety, (858) 534-6418.
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