Estimation of radiocesium dietary intake from time series data of radiocesium concentrations in sewer sludge
Pratama, M. A.; 高原 省五 ; 宗像 雅広 ; 米田 稔*
Pratama, M. A.; Takahara, Shogo; Munakata, Masahiro; Yoneda, Minoru*
After the Fukushima accident, it became important to determine the quantity of radionuclide ingested by inhabitants. The most common methods currently used to obtain such data are the market basket (MB) and duplicate (DP) methods. The newly proposed method, which we designate as SL, consists of three steps: (1) the separation of wet weather and dry weather data, (2) determining the mass balance of the wastewater treatment plant (WWTP), and (3) developing a reverse biokinetic model to relate the amount of radionuclides ingested to the amounts contained in the sewer sludge. We tested the new method using the time-dependent radiocesium concentrations in sewer sludge from the WWTP in Fukushima City. The results from the SL method agreed to those from the MB while overestimated those from DP method. The trend lines for all three methods, however, are in good agreement. Sensitivity analyses of SL method indicate further studies on uncertainties of sensitive parameters are deemed necessary to improve the accuracy of the method.