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Published on: January 30, 2020
Inversion analysis on vertical radiocesium distribution in pond sediment from γ-ray count measurement
Hiroshi Ogawa1, Kimitaka Minami2, Tohru Kawamoto2
1Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, Japan.
Abstract:
Evaluation of vertical distribution of radiocesium in bottom sediment by measuring vertical γ-ray count profile was discussed. A stable inversion formula was derived based on the maximum entropy method. Efficiency of the formula was confirmed by using a low-cost apparatus composed of an array of PIN photodiodes and a single board computer with real-time inversion code. In-door experiment by using five model sediment disks showed good reproducibility of vertical radiocesium profile. On-site experiment was also carried out at a pond in Fukushima to confirm the efficiency. It was suggested that combination of the simple apparatus and MEM inversion formula gave reasonable estimates on vertical radiocesium distribution in bottom sediment of 1 kBq/kg-wet level within about 10 min.
