Nuclear emergency preparedness just for thinking of saving reactors

There had been told no severe accident occurring in Japan. However, all power losses due to earthquake and tsunami caused Fukushima severe accident, which showed no true 'nuclear emergency preparedness' and weak severe accident response in Japan, and then still forced more than one hundred thousand inhabitants to take refuge even after two years passed since. The author had developed 'Emergency Response Support System' (ERSS), which could predict accident progression at reactor accidents, and conducted wide area accident simulation as far as 100 km for future drilling of emergency response. ERSS could predict source terms, which was used input of 'System for Prediction of Environmental Emergency Dose Information' (SPEEDI) to calculate environmental consequences with determining zones for evacuation, sheltering and others. After emergency event corresponding to the article 15 of 'Legislation for Nuclear Disaster' was reported by the operator, more than two hours actually passed by the issuance of Emergency State Declaration, which meant severe accident occurring with containment failure and required residents about 30 km in radius from a reactor to take urgent protective action. If electric utilities could make earlier decision of decommission or injection of seawater into pressure vessel for unit 1 reactor, unit 2 and 3 reactors would be saved with no significant release of radioactive materials into the environment and no exposure damage of affected residents. Protecting the health and safety of residents should be of utmost importance for nuclear accidents. (T. Tanaka)