Measuring Radioactive Contamination - doe-hdbk-1106-97

DOE-HDBK-1106-97

Lesson Plan

Instructor's Notes

C. Measuring Radioactive Contamination

EO3: IDENTIFY the

Because radioactive contamination is radioactive material,

units used to measure

the units are the same, e.g., disintegrations per minute

Radioactive contamination.

(dpm).

When measuring the amount of radioactive contamination

(material) on a surface, the units most commonly used are

disintegrations per minute per 100 centimeters squared

(dpm/100 cm2).

1. Direct reading

Contamination monitors measure radiation emitted by the

radioactive material. The units are normally counts (as

seen by the monitor) per minute (cpm).

2. Discuss counts per minute (cpm) versus disintegrations per

minute (dpm).

Explain counter efficiency.

There is a direct relationship between the counts recorded

and the actual activity (disintegrations) present. The

counter efficiency (expressed as the ratio of cpm/dpm) is

divided into the measured cpm to obtain the activity.