Md Moudud Hasan, Tim Vidmar, Jos Rutten, Michel Bruggeman, Leen Verheyen, Olivier Van Hoey, Marijke Huysmans

Research output: Unpublished contribution to conferencePoster

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An accurate estimate of the three-dimensional distribution of radioactive contamination is important for impact assessment and remediation option evaluation of an affected site. To reduce both the measurement uncertainty and the spatial uncertainty of the estimated activity distribution, methodological developments are needed. The main objective of our research was to design and validate a reliable - and sufficiently sensitive measurement technique for in-situ determination of the depth distribution of radionuclide activity in the ground. Two different approaches were considered. In the first one, gamma-ray spectroscopy of contaminated soil layers was carried out by lowering a Lanthanum Bromide (LaBr3:Ce) scintillation detector into a borehole down to a depth of 100 cm in 5 cm steps. The detector also provided a direct dose-rate reading, which was used for comparison with the TLD measurements that formed the basis of the second approach. The TLDs (Thermoluminescence Dosimeters) were attached to a stick and placed into the same borehole at the soil depths corresponding to the LaBr3 measurement to measure the dose accumulated over a period of time. During borehole drilling, soil samples from each 5 cm layer were also collected for low level gamma spectrometry analysis in laboratory conditions using a HPGe detector. Then, Monte Carlo simulations with the PENELOPE package were used to calculate the LaBr3 detector efficiency required to convert the measured peak count rate into the specific activity of a certain soil layer and to disentangle from it the contribution of the adjacent layers. In a similar manner, the TLD method also has the goal of deducting the activity concentration by combining dose rate measurements and results from Monte Carlo simulations assuming that the radionuclides are known. This is in many ways a more practical alternative to spectrometric measurements, which are not possible in all geometries and are quite labour intensive. At a Cs-137 contaminated site, the specific soil activities obtained with both the spectrometric method and the TLD approach are in good agreement with the laboratory results. The suitability of both methods is evaluated.
Original languageEnglish
Number of pages1
Publication statusPublished - 26 Apr 2019
EventIN SItuNUclearMEtrology as a tool for radioecology – INSINUME 2019 - Kuşadası, Kuşadası, Turkey
Duration: 23 Apr 201926 Apr 2019
Conference number: 8


ConferenceIN SItuNUclearMEtrology as a tool for radioecology – INSINUME 2019
Internet address


  • Activity depth distribution
  • In-situ measurement
  • Gamma-ray spectrometry
  • TLD
  • Borehole
  • Site characterisation


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