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Thin Layer Activation (TLA)

In this corrosion monitoring technique developed from the field of nuclear science, a small section of material is exposed to a high energy beam of charged particles, to produce a radioactive surface layer. For example, a proton beam may be used to produce the radioactive isotope Co-56 within a steel surface. This isotope decays to Fe-56, with the emission of gamma radiation. The concentration of radioactive species is sufficiently low, that metallurgical properties of the monitored component are essentially unchanged. The radioactive effects utilized are at very low levels and should not be compared to those of conventional radiography. The change in gamma radiation emitted from the surface layer is measured with a separate detector to study the rate of material removed from the surface. The radioactive surfaces can be produced directly on components (non-intrusive) or on separate sensors (intrusive).