Analysis of the wind data and estimation of the resultant doses from the supersonic anemometer

Statistical analyses and comparisons of the wind data obtained by the propellar and supersonic anemometers for the year of 1987 in Japan Atomic Energy Research Institute, Tokai Establishment were performed. The resultant average air concentrations and ground level external γ exposure rates due to the radioactive releases for the normal operation of a nuclear power plant are over-estimated when calculated using the properller wind data. The difference is due to the influence of low wind speeds. If the frequencies of low wind speed are large, wind data observed by the supersonic, which could measure even low wind speed more precisely then the propeller, should be used in the atmospheric dispersion analysis to yield a more accurate and realistic estimation of the air concentration and ground level external γ exposure rate. The analysis also shows that the adult thyroid exposure dose of the postulated accident is sufficiently accurate and valid when estimated basing on the contributions of individual iodine nuclides without considering their decay and using the supersonic wind data without having to modify the assumed mean wind speed of the calm. For the external γ whole body exposure of the postulated accident, accurate and realistic estimation should base on the contributions of individual radionuclides with their decay considered and use the supersonic wind data for atmospheric dispersion analysis. (author)