Radioisotope level measurement technology
Gamma rays are short-wave electromagnetic waves emitted from radioactive sources. They are used for measurements more often than other types of nuclear radiation due to their high penetrating power. These rays are absorbed by passing through the medium. The amount of absorbed radiation depends on the path length of these rays in the medium and its density.
where, Io is the intensity of the incident radiation, I is the radiation intensity after passing through a layer of material with thickness x, density ρ and mass absorption coefficient µ. The mass absorption coefficient depends on the γ-radiation power and the absorption properties of the material.
γ-radiation emitted from radioactive sources, such as cobalt-60, cesium-137, etc., passes through the walls of the tank, as well as the controlled substance in it and the air space above it, before reaching the radiation detector (see fig.). The intensity of the measured radiation depends on the level of the monitored substance in the tank, for example, when the level of the measured material rises, the energy reaching the detector decreases. Electronics converts this change in energy into a change in level.
Since no elements of the measuring system are in contact with the substance being measured, the use of such devices with aggressive, high-temperature, pressurized control materials is permissible. They are characterized by high measurement accuracy.