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Tsutsumi, Masahiro; Oishi, Tetsuya*; Yamasoto, Kotaro; Yoshida, Makoto
JAERI-Research 2004-021, 43 Pages, 2004/12
JAERI-Research-2004-021.pdf:8.55MB
We have designed and developed a 
measurement system to certify radioactive wastes below the clearance level. By advancing non-destructive -ray assay technology, it aims at quantitative determination of radionuclides contained in 200 litter drum/container wastes. Unlike the waste from a nuclear power plant, you have to assume that the waste originating from radioisotope usage and nuclear research laboratory have a variety of contents and a complex mixture of radionuclides, and furthermore the uniformity of activity concentration is unknown. To cope with the problems, we have developed the -ray measuring instruments (units) with effective improvement of capability against each problem. They are (1) germanium spectrometry unit for enhanced peak identification, (2) positioning detection unit for positioning of interactions and (3)high-efficiency detection unit for separation of low-energy component. This report summarizes the direction of the clearance level measuring system and the three developed measuring units with their performances.
Tsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto
Journal of Nuclear Science and Technology, 39(9), p.957 - 963, 2002/09
Times Cited Count：3 Percentile：23.41(Nuclear Science & Technology)An anti-Compton spectrometer with semi-2
Compton suppression is designed to identify the photons emitted from low-level radioactive wastes from radioisotope usage and nuclear research laboratory. Since the objective sample is massive and large, the system has a full opening towards the sample position. The characteristics and features of the system concerning Compton suppression and reduction of the background component due to natural radioactive source are estimated by the Monte Carlo simulations. The anti-Compton technique is shown to be quite advantageous for the reduction of the surrounding natural background radiation, as well as the suppression of the background for the higher energy photons.
detection system in the indoor environments of concrete buildingsTsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto
Journal of Nuclear Science and Technology, 38(12), p.1109 - 1114, 2001/12
In order to predict the indoor background spectra to gamma detection systems, the gamma radiation field in a concrete building is studied by the Monte Carlo simulations. The parameters of wall thickness, room shape and dimensions were considered in the modeling. The indoor source geometry was simulated by a spherical layer model with the intention of easy and effective calculations. The model was applied to an unshielded germanium detector and the detection system with a more complex shielding configuration. As the results, we found that the indoor radiation field in concrete buildings can be predicted well with the source geometry of a spherical concrete layer of 25cm thickness and with the source of the natural major three components of the 
U series, 
Th series and 
K that are homogeneously distributed. The simulation model is useful for designing and optimizing gamma detection systems or shielding assemblies.
