Chipless Passive Sensor for Wireless Monitoring of High Radiation Doses in Nuclear Infrastructures

International audienceThe dosimetry is one of the crucial techniques that are needed to assure personal safety and facilities security in the areas of high radioactivity as nuclear power plants or powerful experimental research infrastructure (LHC, XFEL, ITER). Until now, the common electronic dosimeters are based on the silicon diodes or field effect transistors what limits the measured dose value up to few Mrad, as the higher levels lead to the device saturation. The other techniques that allows for higher dose measurement (up to 100 Mrad and more) are based mostly on the variation of physic-chemical parameters of different materials but need the post measurement treatment of the sensor that has to be taken out of the monitored zone and use of the special equipment what makes the continuous measurement impossible. Moreover, in case of nuclear reactors the access to the radioactive zones is limited what leads to the measurement frequency in range of a few times per year. The solution that may overcome that problem is the use of the recently developed innovative concept of the passive sensors that are interrogated by the radar technique. Such a solution uses the small (millimeter sized) micro-resonators designed for the ultra high frequency (about 30GHz) that are connected to the antenna and serve as its load. Any change of the resonant frequency of the resonator may be detected as the shift in the radar echo of the antenna. The sensor is interrogated by the directional radar and the reflected signal is analyzed. The associate transduction principle is that the resonator changes its resonant frequency due to the variation of the specific measured physical value like temperature, pressure or humidity. In our case, we proposed to use the known principle of Hydrogen-pressure dosimeters (HPD) w