Uncertainty analysis of spatiotemporal distribution of the radioactive materials released during the Fukushima Daiichi Nuclear Power Station accident in the environment reconstructed by atmospheric dispersion simulation

Terada, Hiroaki   ; Nagai, Haruyasu  

For the assessment of the radiological doses to the public due to the atmospheric discharge of radioactive materials during the Fukushima Daiichi Nuclear Power Station accident, the spatiotemporal distribution of radioactive materials in the environment are reconstructed by atmospheric dispersion simulation with the improved WSPEEDI. In this study, the influence of chemical form of I (particle, inorganic and organic gas) in source term on the simulated results was analyzed to assess the uncertainty of the simulation. From the sensitivity test with the chemical form composition, surface deposition distribution of I was influenced according to the property of the chemical forms to deposition processes, whereas time-integrated air concentration was less influenced. From the comparison with the measurement, the surface deposition simulated with the source term in Katata et al. (2015) had a good reproducibility compared with those with extreme gas to particle ratios.