Specifications include, but are not limited to:
A. Use a radioactive sealed source(s) that:
1 Approximates a point source;
2 Is a certified, NIST-traceable, standard source that has an activity or exposure rate accurate to
within 5%; if the activity or exposure rate is determined by measurement, document the
method used to make the determination and traceability to NIST;
3 Emits the type of radiation measured;
4 Approximates the same energy (e.g., Cs-137, Co-60) as the environment in which the
calibrated device will be employed; and
5 Provides a radiation dose rate sufficient to reach the full scale (<1000 mR/hr) of the
instrument calibrated. Use the inverse square and radioactive decay laws, as appropriate, to
correct for changes in exposure rate due to changes in distance or source decay.
B. A record must be made of each survey meter calibration and retained for 3 years after each record
is made (10 CFR 20.2103(a) and 10 CFR 35.2061).
C. Before use, perform a daily check (with a dedicated check source) and battery checks.
D. Instrument readings should be within ± 10% of known radiation values at calibration points;
however, readings within ± 20% are acceptable if a calibration chart or graph is prepared and
made available with the instrument.
E. The kinds of scales frequently used on radiation survey meters should be calibrated as follows:
1. Calibrate Linear-Readout Instruments at no fewer than two points on each scale. Calibration
will be checked near the ends of each scale (at approximately 20% and 80%).
2. Calibrate Logarithmic-Readout Instruments at two points on each decade.
3. Calibrate Digital-Readout Instruments with either manual or automatic scale switching for
indicating exposure rates at no fewer than two points on each scale. Check calibrations near
the ends of each scale (at approximately 20% and 80% of each scale).
4. Calibrate Digital-Readout Instruments without scale switching for indicating exposure rates
at two points on each decade.
5. Calibrate Integrating Instruments at two dose rates (at approximately 20% and 80% of the
dose rate range).
F. Readings above 1000 mR/hr (250 microcoulomb/kilogram of air per hour) need not be calibrated;
however, such scales may be checked for operation and approximately correct response.
G. Include in survey meter calibration records the procedure used and the data obtained. Record the
1. A description of the instrument, including the manufacturer’s name, model number, serial
number, and type of detector;
. A description of the NIST-traceable calibration source, including the calibration procedure,
exposure rate, distance at which it was measured, and date of measurement;
3. For each calibration point, the calculated exposure rate, the indicated exposure rate, the
calculated correction factor (the calculated exposure rate divided by the indicated exposure
rate), and the scale selected on the instrument;
4. The exposure reading indicated with the instrument in the “battery check” mode (if available
on the instrument).