Use of Tc-99m for process description and quality control in material-removing surface treatment processes and for determining the filtering capacity of aerosol retention systems

Abrasive processes are used to clean contaminated surfaces. As a measure of the cleaning quality, the ratio of contamination BEFORE K${}_v$ to residual contamination AFTER K${}_n$ is used as a comparison, the decontamination factor K${}_v$/K${}_n$. In nuclear technology, typical nuclides are used that cause radioactive residues and waste (long half-lives, e.g. Co-60: 5.3 a, Cs-137: 30.2 a). These nuclides are used to control and describe aerosol retention (= filter effectiveness). The affected components and systems are subsequently radioactively contaminated. They must be extensively decontaminated - which causes radioactive waste - or are themselves disposed of as radioactive waste. Tc-99m is used instead of the above-mentioned nuclides. Due to its short half-life (6.01 h), it is possible to determine the cleaning effectiveness of the decontamination and cleaning processes and the aerosol retention of the filter systems very precisely. On the other hand, the Tc-99m activity decays quickly, i.e. the Tc-99m disappears. The components and accompanying materials used can generally be measured without any problems. The measurable residual activity of all materials and components involved in the process and the inspections is below the exemption limits of the Radiation Protection Ordinance. The use of Tc-99m has been standard in nuclear medicine for decades and its application is highly quality-assured.