Three Mile Island Nuclear Power Plant: A History of Nuclear Disasters - Part 2

An accident occurred at the Windscale Nuclear Power Plant in England that caused a radiation leak which spread 200 square miles. Faulty equipment at the plant gave inaccurate temperature readings. The temperature readings showed that equipment was cooler than it actually was. Employees' actions that resulted from the inaccurate readings, caused the reactor to overheat and graphite in the plant to burn. The burning graphite caused a fire that was not fully put out until the next day, when employees released mass amounts of water into the facility to put out the fire and cool off the reactors. Filters installed in the chimneys of the plant prevented some of the radiation from escaping into the environment. But even those precautions could not prevent the wide spread contamination that occurred.

A fire at the Lubmin Nuclear Power Plant in East Germany caused safety systems to fail. Employees quickly acted to release coolant into the facility and avoided a nuclear meltdown.

The accident at Three Mile Island in Pennsylvania resulted from a malfunction in the cooling system. The malfunction in the cooling system caused the reactor to shut down. Rising pressure in the reactor caused a relief valve at the top of the pressurizer to open. The relief valve opened and poured water into the pressurizer, but did not shut when it was supposed to. Employees at the plant did not realize that the relief valve was open, and responded to the increased pressure in the pressurizer by reducing coolant flow. Without any gauges that measured the core coolant level or the position of the valve, the employees wrongfully assumed that the high water levels in the pressurizer sensed by the gauges meant that the coolant level in the core was too high. When the employees reduced the coolant, the system overheated and destroyed the fuel rods, which leaked radiation into the cooling water. Once employees realized what had happened, they were able to release a flow of emergency water into the system to cool it and prevent further mishap.

Nearby residents to the plant who were pregnant and small children were eventually evacuated from the area for health concerns. To date there are still numerous studies investigating the increased rates of cancer and thyroid problems associated with the incident, on top of the sharp change in the rate of infant mortalities that occurred at the time. The health risks associated with the Three Mile Island incident is still a hotly debated topic, but new research is beginning to show the real dangers of radiation contamination.

Read about Chalk River and the Mayak Plutonium Facility nuclear power plant accidents.

Read about Chernobyl and Tokaimura; two modern nuclear power plant disasters.

International Atomic Energy Agency

World Nuclear Association

United States Nuclear Regulatory Commission

People Died At Three Mile Island