Official report on Fukushima identifies failures

Both government and Tepco came in for serious criticism in the 507-page interim report from the investigation committee on the crises at the Fukushima Daiichi and Daiini nuclear power plants after the 11 March earthquake and tsunami. A provisional English translation of the executive summary explained how government agencies were meant to have interacted and cases in which this broke down. It also explained some operational mistakes made by Tokyo Electric Power Company (Tepco) during the accident sequence.

Japanese law requires the quick establishment of a local nuclear emergency headquarters in the vicinity of the affected site. For Fukushima this meant the assembly of key staff at a facility about five kilometres away, but two factors prevented this from working properly: One was the devastation of the natural disasters that took out communications links while also preventing timely travel and the provision of food and water. The other was the lack of radioactivity filters at the building, which actually made it useless for a serious emergency of the kind that developed at Fukushima Daiichi. The report noted gravely that the Nuclear and Industrial Safety Agency (NISA) had been told in February 2009 to install proper filters at the facility but "did not take concrete steps" to do so.

Another mismatch between the management of nuclear emergencies and natural disasters emerged at the prime minister's office, where the main emergency headquarters were situated. There was insufficient communication between the nuclear and the natural disaster sides, and also NISA and the Ministry of Economics Trade and Industry (METI) did not set up adequate information flow from Tepco. Government communications to the public were accordingly delayed and ambiguous.

Tepco was criticised for two potential operating mistakes during the accident sequence. The first was misjudgement of the status of the unit 1 emergency cooling, which operators thought was working normally, but was not. By the time this was noticed and acted upon, major damage had occurred. At unit 3 a wrong decision by shift operators without advice from managers left it without cooling for over six critical hours. More broadly, Tepco had inadequate measures to cope with station blackouts, and had no plans for the seawater injection technique on which it came to rely.

An overall failing of Tepco, NISA, METI and its predecessors was to fail to plan for very large tsunamis. The site was licensed in the 1960s and 1970s on the basis of a 3.1 metre tsunami height, and although later studies indicated that 15-metre tsunami inundation was possible, no concrete steps were taken by any of the bodies to do anything about it.

Japan had established the System for Prediction of Environmental Emergency Dose Information (SPEEDI) for exactly the kind of nuclear emergency presented by the Fukushima accident. Although the earthquake disrupted SPEEDI's operation so that it could not give full results on radiation doses at various places near the accident site, it was still accurately predicting the path of the radioactivity. However, this excellent data was not communicated, and hence not used in planning evacuations.

Copyright © 2012 World Nuclear Association, All rights reserved

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