Environmental assessment of uranium

For the purpose of securing the inhabitant's health, this investigation has been carried out to measure concentrations of uranium in various environmental samples mainly around a nuclear fuel processing factory and at other locations. On the basis of this observation, we have made an attempt to perform an environmental assessment of uranium. 1) Concentrations of uranium in river waters and sea waters determined by a fluorometric technique and in surface soils and airbome dust determined by a neutron activation technique were 0.5 μg 1-1, 2.4 μg 1-1, 2.6 mg kg-1 and 0.1 ng m-3, respectively, around the factory. These values were found at the same level in normal environments. 2) Estimated ratio of the daily uranium intake by inhalation to the daily intake by ingestion was about 1/1700. 3) Thorium to uranium ratio in surface soils, namely about 2, agreed with that in airborne dust. Uranium in airborne dust was supposed to be originated from surface soils. 4) The monitoring techniques that have been used at our laboratory were proved adequate for detecting unexpected releases of excessive uranium into the atmosphere. (author)