Few people will remember that today is the 34th anniversary of the disaster at the Three Mile Island nuclear power plant. Nevertheless, this was a focusing event that solidified resistance towards nuclear power in the United States and remains an example of how poor decision making and crisis communication can turn an emergency into a crisis.
At 4 AM on this day in 1979 a pressure valve failed to close, draining contaminated coolant into adjacent buildings and causing the core to overheat. Emergency cooling pumps were automatically activated but were shut off by the plant workers based on confusing and contradictory readings. It was some four hours later before they realized their error and restarted the pumps. By this time, half the core was melted and the reactor had come within one hour of a full meltdown that would put the surrounding countryside at risk.
This was only the beginning of the crisis. The plant workers had also missed that the overheated core had produced a large cloud of hydrogen gas, some of which exploded and released a small amount of radiation. It was two days later before the gas bubble was noticed. Fearing an explosion and potential meltdown that would release a considerable amount of radiation, the governor advised pregnant women and young children to evacuate the area. The result was a spontaneous evacuation of over 100,000 and considerable public alarm that did not dissipate until April 1 following a Presidential visit and the determination by plant workers that there was no danger of explosion.
The Three Mile Island disaster still has many lessons to teach us. One of the biggest is that the human factor is always at play in disasters. In this case, the crisis was precipitated by the decision to shut down the pumps. That decision was made on the basis of bad information provided by a poorly designed system. A reasonable precaution of evacuating those most at risk produced public concern rather than the calming effect intended. Ultimately, the Three Mile Island disaster almost the devastated the nuclear power industry, coming at a time when there was considerable controversy over the safety of nuclear power plants.