Regional scale atmospheric dispersion simulation of accidental releases of radionuclides from Fukushima Dai-ichi reactor

► Regional scale dispersion of accidental releases from Fukushima Reactor simulated. ► Flow trajectories were mainly westerly with radioactivity dispersed over sea. ► Mesoscale easterly/southeastery flow was simulated on 15-17, 19-21 March'11. ► Plume shift on 15-21 Mach caused deposition of radionuclides over the land region. ► A narrow 80 km high deposition zone simulated in northwest in agreement with data.