Lesson Learned

On March 11, 2011, one of the strongest earthquakes in recorded history struck Japan’s northeast coast. The earthquake and the tsunami that followed killed more than 20,000 people and caused over $200 billion in property damage. The tsunami also disabled critical safety systems at the Fukushima-Daichii nuclear power plant, resulting in damage to its fuel rods and a large release of radioactivity.

Scary though the accident looked and sounded in the media, its radiological consequences are negligible. Nobody has died from radiation exposure. The Japanese government evacuated tens of thousands people from the area surrounding the plant to avoid radiation doses that would have had no measurable effect on their health. On the other side of the world, as the accident was still unfolding, Germany chose to shut down its nuclear plants and replace their output with energy from renewable sources (“The Great German Energy Experiment,”), a decision comparable to giving up driving because a friend crashed a car on a dangerous road. German nuclear plants are among the best-operated in the world, and seismic and tsunami risks in Germany are practically nonexistent. The decision seemed to be more the result of politics and public fear than of logic.

Most countries using nuclear energy were more rational. The U.S., the U.K., France, China, and South Korea, among others, studied the Fukushima accident closely so that they could reduce the likelihood of similar events at their own plants. These countries restated their commitment to the safe and secure development of nuclear energy as a way to combat global warming and ensure energy independence. A number of countries with young nuclear energy programs, such as the United Arab Emirates, Turkey, Vietnam, and Poland, did not significantly alter their plans after Fukushima.

The consensus now is that the tsunami protection system at the Fukushima plant was “underdesigned.” When a nuclear plant loses off-site power, it needs on-site AC and DC power sources to activate safety systems and read instrumentation. At Fukushima, those backup sources were in poorly protected rooms that were overwhelmed by the large waves of water.

Protecting on-site AC and DC power sources in waterproof, fireproof rooms is the simplest way to defend nuclear plants against natural events such as floods, fires, hurricanes, and tornadoes. U.S. plants are already well equipped thanks to measures taken after September 11, 2001. Following the disaster in Fukushima, the U.S. nuclear industry took voluntary action to strengthen protections against natural disasters. The U.S. Nuclear Regulatory Commission recently formalized requirements for extended protection against such events in current and future plants. Nuclear energy will emerge even safer after Fukushima, just as it has after previous accidents. It will continue to produce clean and reliable power for the benefit of humanity.

Jacopo Buongiorno, associate professor of nuclear science and engineering at MIT, works on thermal hydraulics and the safety of nuclear power plants.