A survey is an evaluation of the radiological conditions and potential hazards incident to the production, use, transfer, release, disposal, and/or presence of sources of radiation. When appropriate, such survey includes, but is not limited to, tests, physical examination of location of materials and equipment, measurements of levels of radiation or concentration of radioactive material present.
Surveys are can be performed using two different special units; microroentgens per hour (µR/hr), and counts per minute (cpm).
The roentgen is a measurement of radiation levels existing at any particular point in air where a radiation detector is positioned. The roentgen is the unit of measurement for radiation exposure, particularly gamma ray exposure when working with NORM. The microroentgen per hour (µR/hr) is the basic radiation unit over time used to provide an indication of the amount/concentration of NORM that is being emitted from an object, also known as exposure.
Counts per minute (cpm) is a measurement of loose alpha and beta particle radiation contamination being emitted from a person or an object, which is measured with the Geiger-Mueller “pancake” probe. This unit is primarily associated with the process of surveying personnel called frisking. Gas-processing equipment and facilities are surveyed with the Geiger-Mueller “pancake” probe due to beta particle contamination that is not detectible by the scintillation probe.