Overview of system for prediction of environmental emergency dose information SPEEDI and its worldwide version WSPEEDI

Furuno, Akiko   ; Nagai, Haruyasu  ; Terada, Hiroaki   ; Tsuzuki, Katsunori  ; Nakayama, Hiromasa   ; Kadowaki, Masanao   

SPEEDI (System for Prediction of Environmental Emergency Dose Information) is a computer system that quickly predicts the atmospheric dispersion and the environmental impact of radioactive substances released into the atmosphere in a nuclear accident. During the Fukushima accident in 2011, SPEEDI calculation was executed according to the monitoring guideline by the former Nuclear Safety Commission, but prediction results were not utilized for evacuation planning by decision makers. The Nuclear Regulation Authority concluded that it is not adequate to use SPEEDI for the judgment of protective measures in emergency because it is difficult to accurately predict the timing and amount of release. However, the usefulness of SPEEDI has not been denied, and the local government can utilize SPEEDI with their own judgment and responsibility. We will also present our activities for the Fukushima accident, mainly about the release amount estimation.