APPENDIX BB

Surveying for Direct Radiation Exposure

1. The user of the survey meter should thoroughly read the instruction manual and become familiar with the switches and settings.
2. It is important to verify the instrument's batteries are charged by setting the scale selector switch to "battery check" or by pressing the "battery test" button. The needle should read on or near the appropriate indicator on the scale. If low batteries are indicated, they should be replaced.
3. If a "check source" is attached to the instrument, the probe should be placed against the source and the reading observed to assure the probe is functional. If the check source reading is recorded somewhere on the instrument, the measured level should be compared with the recorded reading. Variations of more than ten percent may be an indication of probe malfunction. If a check source is not attached to the instrument, it is advisable to check the probe operation with any available radiation source (e.g., stock vial)
4. The instrument should be switched "on" before approaching any radiation source. Some GM tubes can be "saturated" when exposed to high radiation fields resulting in false negative readings.
5. At the beginning of the survey, the scale switch should be set on the highest scale (usually x10 or x100) and sequentially reduced to the next lowest position until the needle begins to register. It is important to pause at each scale setting to allow the needle to stabilize.
6. If the meter needle "pegs" (goes off scale) during the survey, sequentially increase the scale selector, again, pausing at each setting to allow the meter to stabilize. Some instruments have a "reset" button which "zeroes" the needle on each scale setting.
7. Throughout the survey, the meter readings should be documented (remember to multiply by the appropriate scale setting). Documentation should also include the name of the person performing the survey, the survey meter model # and serial #, and the date of the survey.
8. Upon completion of the survey, the instrument should be switched off to avoid discharging the batteries. It should be noted that some instruments have a separate switch (and batteries) for the speaker; therefore, it is important to switch off the speaker of these instruments as well to avoid discharging the speaker batteries.
9. If the instrument is not used for an extended period of time, the batteries should be removed to prevent instrument damage from corrosion.

Surveying for Contamination

1. Before initiating a survey for contamination with a survey meter, steps one through four from "Surveying for Direct Radiation Exposure" (previous page) should be followed.
2. When surveying for contamination, the scale switch should initially be set on the lowest scale and sequentially adjusted to the next highest scale should the meter needle go off scale.
3. It is important to move the probe slowly when performing these surveys and the probe should pass within two cm of a potentially contaminated area. It is equally important to avoid contaminating the survey probe.
4. Speakers and/or headphones are very helpful when surveying for contamination because they respond more rapidly than the meter needle to variations in the contamination levels being detected by the probe.
5. It should be noted that exposure rate readings (i.e. mR/hr) are intended for photon (e.g. x-rays or gamma rays) radiation only. Beta radiation readings should be read and recorded as cpm if the instrument is equipped with a cpm scale. Otherwise, beta radiation measurements may be recorded in arbitrary units of mR/hr; however, such measurements of beta radiation do not necessarily reflect the actual skin dose rate. The efficiency of a Geiger counter and survey probe for various energies of a beta-emitting radiation is provided on a tag at the time of instrument calibration. To determine the activity being detected, use the following formula: dpm = cpm/efficiency
6. Steps six through nine from "Surveying for Direct Radiation Exposure" should be followed to complete the survey for contamination. Swipe surveys are required in areas where contamination is detected by the survey meter to determine if the contamination is fixed or removable. Decontamination procedures should be implemented as necessary.