Development of an automatically operating radon exposimeter "au.raex" for occupational radiation protection dosimetry related to Radon

Status:

completed 10/2023

Aims:

The research project "Development of an automatically switching radon exposimeter 'au.raex'‚ for the improvement and simplification of personal and local dosimetry in connection with radon", focuses on the measurement of alpha radiation, which is released during the decay of the radioactive gas radon. As conventional dosimeters cannot be used here and the method currently used often leads to over- or underestimates of radon exposure, a new exposimeter "au.raex" is to provide a near-series prototype that can interrupt the measurement to enable more accurate, time-resolved exposure data during working hours.

Activities/Methods:

The project is divided into three work packages: Requirements definition, product development and test phase. In the first work package, the requirements are defined in collaboration with the employers' liability insurance association. The Institute for Product Development at the Karlsruhe Institute of Technology (IPEK) then develops the prototype in the second work package. This is to feature three different operating modes: manual, timer and motion mode. The test phase and thus work package three, divided into laboratory tests and tests with test persons, is intended to check the functionality of the different modes.

Results:

During the development of the prototype, a sealing concept was found and implemented that operates very robustly, does not lead to jamming and can be designed to save space. In addition, the air exchange in the measuring chamber is promoted by the operating principle of a piston. The three operating modes were implemented in the programming of the microcontroller, supported by the respective sensors. A triaxial MEMS acceleration sensor is used for motion detection, which communicates with the microcontroller via interrupts at adjustable threshold values. During the project period, the housings of the prototypes were successfully tested for leaks. The tests with the manual and time-controlled (timer) mode under laboratory conditions were also successful. However, the planned test phases in the field to check the motion-controlled operating mode could not be fully completed.

The test results to date show that both the manual mode and the timer mode were able to measure the expected radon concentrations. However, the timer mode has limitations in the field, as the setting of fixed opening and closing times before the start of exposure means that any missing times cannot be taken into account without separate documentation. Furthermore, the motion mode is not yet sufficiently functional to be operated autonomously and provide reliable values. The goal of a near-series prototype has therefore not yet been fully achieved and further development work is required.

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