Continual and simultaneous measurements of individual concentrations of short-lived radon daughters (RaA, B, and C) were performed in a house under normal living conditions and in the open air. Based on data collected over a period of two years, the relationship between indoor and outdoor radon daughters was discussed. The averaged diurnal variation and the seasonal variation of radon daughters in indoor air showed the same pattern as those in outdoor air. From a comparison of the variation patterns with the inhabitants' living habits, it was estimated that in this house the contribution of human activities to concentrations of indoor radon daughters was smaller than that of natural activities, such as those featuring meteorological factors. The concentrations of indoor and outdoor radon daughters depended strongly on wind velocity and outdoor temperature, and no difference was found between indoor and outdoor air in the influencing factors. Based on the linear combination of the two meteorological factors, prediction of the level of the daily mean of the nuclides was attemped. Despite the simple methodology, the predicted values were found to agree with the experimental ones with considerable accuracy.
The performances of assessment models for estimating the transfer and bioaccumulation of mercury in a lake ecosystem were tested by being applied to a test scenario proposed in an international cooperative study named BIOMOVS. Two kinds of models have been developed to estimate mercury concentration in fish. One uses a bioaccumulation factor approach which is applied to an ecosystem in equilibrium, whereas the other is a dynamic model in which both the change of the concentration in water and the metabolism in fish are taken into account. For this scenario, the former was not adequate but the latter could predict more accurately because the concentrations were not in equilibrium. The limitations of applications were suggested for the two models employed here. It would be important in the present case to take into account that equilibrium was not attained in the ecosystem and the metabolism of mercury in the fish was very slow.
Several types of electric pocket dosimeters have been developed recently. These dosimeters are distinguished by use of the silicone semiconductor as a radiation (γ-ray, X-ray) detector. Performance tests of a type of dosimeter named the PDM102 were carried out by using a 60CO point source (about 500kBq). The results showed that the minimum detectable dose equivalent for the dosimeter was 1-2μSv. Excluding cases of exposure from the underside or back of the dosimeter and exposure of less than 10μSv, differences between measured and calculated dose equivalents were less than 10%. Consequently the effect of the dose equivalent rate and dose equivalent (>10μSv) on the response of the detectors was determined to be less than 10%, and the directional dependence was also less than 10%. The dosimeter's response for back exposure was about 70-80% of that for front exposure. And for exposure from the underside of the dosimeter, the measured dose equivalents were equal to or less than approximately 50% of the calculated dose equivalents.