Cascading Geohazards and Radiological Consequences: Lessons from the Fukushima Daiichi Nuclear Disaster for Integrated Risk Assessment and Worker Protection

The world’s view of nuclear safety was altered on March 11, 2011. That day, a magnitude 9.0 earthquake shook the coast of the Tohoku region of Japan. The earthquake triggered a tsunami that wiped out the back-up power at the Fukushima Daiichi nuclear power plant. As a result, three of the plant’s reactors overheated and experienced core meltdowns that released radioactive contamination into the land, groundwater, and ocean over thousands of square kilometers. What happened at Fukushima was not one disaster, but a series of five disasters, with each disaster triggering the next. In this paper, the author treats the Fukushima incident as a cascading series of geohazards that link the severe rupture of the earth’s crust, with tsunamis, nuclear reactor accidents, and long-term contamination of the land with radionuclides, to other geohazards prompted by the extensive decontamination efforts as a result of the nuclear disaster. An assessment is provided of where the protection of workers failed for each kind of geohazard, and the need for a multihazard risk assessment approach is proposed. The single hazard approach to risk assessment and regulation that existed prior to 2011 and post-Fukushima has not failed because it was poorly implemented. It is not faulty. It is the case that no one hazard was responsible for the Fukushima disaster. It was a combination of hazards that challenges nuclear facilities that seek to exist within an earthquake and/or tsunami risk zone.