Estimation of radionuclide emission during the march 15, 2011 accident at the fukushima-1 npp (japan)

Transport of radioactive substances in the atmosphere was modeled on the basis of the Lagrangian stochastic model of the dispersion of radionuclides in the atmosphere. The WRF-ARW regional hydrodynamic model was used to reproduce the change of atmospheric conditions. Radiation monitoring data showed that the main radioactive contamination of the territory of Japan occurred on March 15, 2011. For the rest of the time the radioactive cloud was carried by the wind, mainly in the direction of the Pacific Ocean. Estimates of the equivalent dose rate at the points where the radiation conditions were monitored on the territory of Japan were obtained by modeling the transport of radioactive substances taking account of actual atmospheric conditions. The computed equivalent dose rate differs by a factor of 2–3 from the results of aerial gamma surveys. The computed 137 Cs content differs from the measured value by not more than 50 %.