Number 31 July, 2000

"To Survey and Protect"

Preventing and policing contamination are two of the most important work practices in any radiation laboratory. Routine surveys allow you to find contamination before it spreads, protect yourself from harm due to accidents, prevent harm to others, assess the progress of decontamination efforts, and stay in compliance with the rules and regulations.

ORS's periodic visits function as a check on the quality of your work practices and surveys. Proper survey meter use becomes second nature when surveys are a routine part of your workday. They don't need to be tedious and time consuming; a quick check of the work area and your hands and clothing may be all that is needed to give you peace of mind. This article addresses use of portable survey meters. If you use H-3 you must survey using the wipe test method counted in liquid scintillation.

Even a quick survey needs to be done properly for it to be effective. Check the batteries and check the operation with a source of radiation each day you use a survey instrument. You could point the detector at a source vial or even a radwaste container. If the batteries are low or the meter does not respond, correct the problem immediately or remove the instrument from service and tag it for repair. [Tip: State inspectors like to ask radiation workers if they check meter operation before use.]

The survey method is equally important. You generally will survey using the lowest and most sensitive scale. Know the ambient background in the lab; measure it away from any source of radiation before you start to survey. Move the detector slowly over the surface without actually touching it. Be alert to small deviations above background; when you notice them, pause the detector over the spot and see if the count rate continues to rise. Don't touch the surface of the detector and keep it away from sharp objects, or you could get a rude and expensive surprise when the window "pops." If you are surveying an area with a high background, such as next to a waste container, wipe the surface with a filter paper, take it to a place with lower background and measure it there.

Places to check in addition to the benchtop include centrifuges, incubators where S-35 methionine has been used, vortex mixers, trash cans, the floor at the work area, sink surrounds, the floor or bench around waste containers, the fume hood sash (where you put your hand on it to push it up and down), the rims of stools, and chair backs.

Finally, take a look at the calibration sticker on your survey meter. If it is more than a year old, call ORS to arrange for testing and calibration.

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Comfort and safety can go hand-in-hand in the laboratory during the summer months. Travel in shorts and sandals but change into more substantial clothes and shoes when you get to the lab.