On the basis of the measurement results of airborne radionuclide concentrations in the Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, the committed effective dose to adults and the committed equivalent dose to thyroid of infants by inhalation were estimated for various indoor and outdoor exposure scenarios. It was demonstrated that the indoor to outdoor airborne radionuclide concentration ratio had a dominant effect on the dose estimate. The committed effective dose to adults was estimated to 0.098 mSv, and the committed equivalent dose to thyroid of infants was 1.8 mSv. These doses were about 1/6 and about 1/9, respectively, compared to the provisional ones with such assumptions as continuous outdoor stay.
Potting soil can be often composed of variety of soils such as Akadamatsuchi, Kurotsuchi, and so on. In this study, root uptake of radiocesium (134Cs, 137Cs) by mini cabbage growing on various potting soils was studied. Three kinds of potting soils that contained any one of radiocesium contaminated Akadamatsuchi, leaf-mold and sludge were used for planting the mini cabbage. Concentrations of radiocesium differed among these potting soils: 3.4 × 101 Bq/kg in soil with Akadamatsuchi, 2.4 × 103 Bq/kg in soil with leaf-mold, and 3.5 × 103 Bq/kg in soil with sludge. At the harvest time, the concentrations of radiocesium in the mini cabbage were below 100 Bq/kg, which is the new standard limit for general foods by Japanese guidelines. The highest soil-to-plant transfer factor of 0.13 was observed for the soil with Akadamatsuchi. In addition to the high transfer factor, Akadamatsuchi is the most commonly used material for potting soils, and thus it may be necessary to pay attention to the radiocesium contamination in Akadamatsuchi. Foliar uptake of radiocesium by the mini cabbage was also studied, but the concentration of radiocesium did not increase in the plant under our experimental conditions.