For more than fifty years, atmospheric dispersion predictions based on the joint use of a Gaussian plume model and wind tunnel experiments have been applied in both Japan and the U.K. for the evaluation of public radiation exposure in nuclear safety analysis. The effective source height used in the Gaussian model is determined from ground-level concentration data obtained by a wind tunnel experiment using a scaled terrain and site model. In the present paper, the concentrations calculated by this method are compared with data observed over complex terrain in the field, under a number of meteorological conditions. Good agreement was confirmed in near-neutral and unstable stabilities. However, it was found to be necessary to reduce the effective source height by 50% in order to achieve a conservative estimation of the field observations in a stable atmosphere.

The Fukushima Dai-ichi nuclear power plant accident led to the dispersion of radioactive material by wind that resulted in soil and air pollution over a wide area. Even now, more than 150,000 people in Fukushima prefecture are still relocated from their homes. In order to estimate how long such relocation might continue, we estimated radiation exposures for the 10 years following the accident that occurred on 12 March 2011, using European model for inhabited areas (ERMIN) developed by a partnership of several European organizations. We validated the estimated results of long-term radiation exposure with the observed data at 1, 2 and 3 years after the nuclear accident. We analyzed the deposition velocity and re-suspension coefficient using the observed data on air concentration, amount of falling dust and soil contamination, and compared them with the published data.

The purpose of this study is a discussion on the multifaceted utilization of indoor positioning systems such as building facility control, use situation grasping, and operational analysis in offices. Thermopile human sensors have been come into practical use by MEMS (Micro Electro Mechanical Systems) technology and are becoming widespread. In this report, the accuracy of presence / absence and human count detection for a thermopile human sensor was verified and discussed possibility of use according to the purpose in the office.

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The purpose of this report is the improvement of the source intensity estimation. Accuracy improvement of source intensity estimation were performed on the following 4 uncertainties. 1) Uncertainty of wind direction was decreased by expanding observation time. 2) Uncertainty of emission height was decreased by removing observation data measured near a source point. 3) Terrain influence was reproduced in modified Gaussian plume model, based on wind tunnel experiment. 4) Meandering effect was reproduced by using the variance of wind direction in the field. It was verified that accuracy was improved and order estimation can be performed by these methods.