[en] In the environmental assessment for nuclear power stations and others, it is ideal to monitor the meteorological conditions above the sites continuously. However, it is difficult due to labor, expenditure and weather conditions. The observations of wind profiles with a doppler acoustic wind sensor and of temperature profiles with a siplified temperature radiosonde were carried out. It is possible to substitute for the conventional methods such as towers, pilot balloons and lower level radiosonde. The results of their feasibility studies are described. In the former method, acoustic pulses in narrow angle are sent upward by a transmitter, and the three-dimensional move of the scattering media is measured as doppler shift by a receiver. In the latter method, there are advantages of compact size, wide temperature range and the acquisition of stable temperature distribution. (J.P.N.)

[en] The unstable stratified boundary layer that was analogous to unstable atmospheric boundary layer was created in CRIEPI wind tunnel. The overall Richardson number was equall to -4.0 in the unstable flow condition in the wind tunnel and under this condition velocity and temperature fluctuation was measured. Auto-correlation coefficient and power spectram of velocity and temperature fluctuation were calculated and compared with those, of field experiments. Fothermore tracer gas diffusion experiment was mad in the wind tunnel and it's apparant that vertical plume spread in unstable condition was nearly equall to that of atmospheric stability B in Pasquill-Fifford chart. (author)

[en] This report presents a system for the prediction of the consequences of an accidental atmospheric release from nuclear power plants. In this system, consentration distributions are calculated with a three-dimensional Gaussian plume trajectory model. The potential flow model or quasi-potential flow model is used to provide the three-dimensional space- and time-varying advection field to the trajectory diffusion model. The meteorological data required by those wind field models are observed or forecasted winds at a certain point typical of inflow boundary conditions. The forecasted winds are calculated from a statistical model using the principal component analysis and the maximum entropy method. The diffusion parameters are estimated from the concentration distributions measured with wind tunnel experiments for the topographical models of a site of interest and its surroundings. The gamma exposure rates due to radioactive plumes are calculated from a simplified exposure model based on a plume segment model. The system designed in this report has the following features: 1. The system is applicable to real time estimations of concentration and dose due to radioactive plumes released from a nuclear power plant located in complex terrain. 2. The system requires only the wind directions and velocities at one representative point for the meteorological data necessary for the evaluation of the current concentration and dose. The observation network of the AMeDAS of Japan Meteorological Agency can be utilized for forecasting meteorological variables. 3. The system is operational without technical knowledge on calculation methods and easy to use. (author)