Verification! Predicted information provided from SPEEDI during the Fukushima Daiichi nuclear accident. Accuracy, timeliness and future utilization

During the Fukushima Daiichi nuclear power reactor accident, SPEEDI were providing related authorities with predicted information on atmospheric dispersion, but it was accused that the information were not used for countermeasures of evacuation, etc. This paper describes what kind of prediction were carried out, when these were provided to authorities and how were the accuracy of these information. Furthermore, on the basis of these investigation, the future effective utilization of SPEEDI is proposed. (J.P.N.)