Modeling Migration of Cs-137 in Sewer System of Fukushima City Using Model for Radionuclide Migration in Urban Environment and Drainage System (MUD)

Abstract—Following Fukushima Daiichi Nuclear Power Plant accident, Cs-137 has entered sewer system of Fukushima City which was confirmed by detection of the radionuclide in dewatered sludge of waste water treatment plant (WWTP). Consequently, the sludge could not be transported to landfill facility due to radioactive content. Conducting simulation on migration of Cs-137 from urban area into WWTP becomes the objective of this study. MUD, a compartment model consisted of urban and WWTP sub model was used in this study. Migration process is simulated based on natural process and decontamination activities. Value of the parameters used in this study is combination between default general value and site specific value. The result of the model showed an agreement with observed data with 85% of the data in range of 10-90 percentiles of observed data. Value of R2 between modeled and observed data about 0.84 shows the model could explain the seasonal variation occurred in real condition.