Analysis of internal radiation dose through dynamic ingestion pathways

The time-dependent radioecological model which is applicable to Korean environment, has been developed in order to assess the radiological consequences following the short-term deposition of radionuclides in an accident of nuclear power plant. Transport of fallout radionuclides through food chain to man and the radiation doses resulting from the consumption of contaminated foods were estimated by this model. Variation of radioactivity concentrations of radionuclides in soil, foodstuffs and feed stuffs can be described as a function of time following the deposition. Transport of radionuclides was analyzed in the successive compartments representing various environmental elements or foodstuffs. Dynamic variation of radioactivities were simulated by considering several effects such as deposition, weathering and washout, resuspension, root uptake, translocation, leaching, senescence, intake and excretion of soil by animals, intake and excretion of pasture-grass by animals, etc. Seasonal variation of radioactivity was also considered which was dependent on the deposition time. The input for calculation in this model are the deposition amount[Bq/m2]. the time of the year at which the deposition happens, duration for calculation, and the kind of radionuclide and foodstuff for estimation. The effective ingestion dose was calculated and analyzed with the committed does equivalents as the function of time for each foodstuff and adult. Three kinds of critical radionuclides for ingestion pathway, thirteen foodstuffs, and two feed stuffs were considered in this study. Agricultural data in Kori region was used. From the results of this study, it has been demonstrated that the ingestion dose shows a very pronounced seasonality depending on radionuclides and foodstuffs. In order to validate results by this model, the calculated results were compared with those by ECOSYS-87, a Germany model. Further studies should be done in the analysis of uncertainty, which resulted from the model itself and the accuracy of data sets especially in the field of time-dependent data