B. Points to consider if interpreting the measurement of contamination

There are many problem areas when attempting to interpret a contamination measurement. Some of the more important are: 

• Surface - detector distances because close monitoring may be required.
• Dead time - if the correction is not built into an instrument’s scale, it can be accounted for.
• Instrument detection efficiency - this may be complicated, especially if multiple emissions occur.
• Absorption of radiation by surface coverings (e.g. paint, grease) - in some instances the effect of a coat of paint may be that the contamination is not detectable at all.

Precise measurements are rarely required and, providing rational assumptions are made and realistic uncertainties are determined, contamination monitors and wipe test techniques can be used to provide estimates of activity levels present.

Guidance on the specialist task of estimating surface activity can be found in module ‘Estimating surface radioactivity’.

 

Good practice online modules

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• Practical radiation monitoring
  
• Practical radiation monitoring units
• Radiation monitoring strategy
• Choice of radiation instrument 
• Radiation monitoring techniques  
• Estimating surface radioactivity
• Radiation instrument calibration
• Uncertainties in radiation measurement 
• Troubleshooting in radiation monitoring