CONTAMINATION CONTROL

Contamination can be measured at levels far below those that are hazardous.

For first responders with protective clothing and respiratory protection, external radiation is normally by far the greater hazard.

When leaving the scene of the emergency you leave the radiation behind, but you can take contamination with you. Check for contamination before you leave the area.

Contamination Control Methods

When a person or item leaves an area with a potential for contamination, strict procedures should be put into place to control the contamination and prevent its spread.

These include:

A survey of personnel for contamination A survey of equipment for contamination

While emergency actions take priority, remember that cleaning up after an emergency includes contamination surveys.

During an emergency you do not worry about getting the equipment dirty.

After the emergency you must clean the equipment.

In the case of an emergency involving radioactive materials, all equipment must also be surveyed for contamination prior to being removed from the area.

Protective Clothing

Protective clothing (e.g., “Anti-Cs”) keeps contamination off your skin and personal clothing.
You could use standard coveralls, but fire department turnouts are as good (or better) and serve the same purpose.

When working in contaminated areas, you should use masking tape (or similar) to seal the openings of your protective clothing and prevent contamination from getting through any openings.Button top shirt buttons and roll down shirt sleeves if no other protective clothing is available.






When working in contaminated areas, you should use masking tape (or similar) to seal the openings of your protective clothing and prevent contamination from getting through any openings.

Button top shirt buttons and roll down shirt sleeves if no other protective clothing is available.













When removing contaminated clothing, care must be taken to prevent cross contaminating your under clothing, you skin, or the area around you.









Contamination Monitoring Equipment

Radioactive contamination can emit alpha, beta, and/or gamma radiation.

Several hand probes have been developed for count rate meters to detect the various types of radiation emitted from contamination



Monitoring for Fixed Contamination



Beta-Gamma Contamination Monitoring

Beta-gamma contamination is normally monitored using a “Pancake” type Geiger-Mueller (GM) detector and is designed for contamination surveys of personnel, table tops, floors, equipment, etc.
Survey for beta-gamma contamination at a distance of 1/2 inch and at a speed of 1-2 inches a second.
Warning: The mica cover on the probe is very fragile and will pop very easily



Alpha Contamination Monitoring

Alpha contamination is normally monitored using a scintillation-type detector.

Measures light produced inside the detector by the interaction of an alpha particle with detection medium.

Designed for contamination surveys of personnel, table tops, floors, equipment, etc.

Survey at a distance of 1/4 inch and at a speed of 1-2 inches per second.
Warning: Even a very small hole in the mylar can cause erroneously high readings


Performing a Whole-Body Survey

Perform a detailed, whole-body survey of all exposed surfaces for the appropriate type(s) of contamination (alpha, beta-gamma, or both alpha and beta-gamma).

Start at the head and proceed to the feet. Pay particular attention to the following areas: contaminated area (if known), nose and mouth, hands, skin folds, buttocks, knees, and feet.

Move the probe at the appropriate speed and hold it at the proper distance.




Performing the Survey













If the count rate increases during the survey, pause for 10 to 15 seconds over the area to provide adequate time for instrument response.

If the count rate once again increases, or the instrument alarms, the presence of contamination is confirmed.

If contamination is confirmed, remain in the area and notify radiological control personnel.

Whole-body surveys should take several minutes. Do not hurry!