Estimation of dry deposition velocities of radionuclides released by the accident at the Fukushima Dai-ichi Nuclear Power Plant

Takeyasu, Masanori ; Sumiya, Shuichi 

On the basis of I-131 measured after Fukushima primary nuclear power plant in nuclear fuel cycle engineering laboratory and atmosphere radioactive material concentration of cesium isotope and atmospheric deposition quantity data, the deposition velocity of atmosphere radioactive material to the surface was estimated. As the result, the deposition velocity was the 10m/s order. It was the order equal to I-131 deposition velocity estimated after Chernobyl accident estimated from until now environmental radiation monitoring result around Tokai Nuclear Fuel Reprocessing Plant from the monitoring result in I-129 deposition velocity and this laboratory. It was guessed that it included the gaseous component for I-131 and cesium isotope discharged by Fukushima accident in atomic powered generation and that the deposition velocity varied by the ratio of the component.