Perhaps the Worst, Not the First

The estimated 375 commercial nuclear power plants in operation around the world have now built up more than 3,800 years of experience. But since the first one went on-line at Obninsk in the Soviet Union in 1954, there has always been the fear of an accident. The vast majority of malfunctions pose no serious health threat, yet some problems have required emergency measures. A worldwide count of accidents and casualties at nuclear facilities cannot be made with precision because the Soviet Union, a major user of nuclear power, does not divulge information about such problems until they become impossible to disregard or deny. Some of the most serious reported nuclear mishaps:

Dec. 12, 1952. Accidental removal of four control rods at an experimental nuclear power reactor at Chalk River, Canada, near Ottawa, led to a partial meltdown of the reactor's uranium fuel core. A million gallons of radioactive water accumulated inside, but there were no accident-related injuries. Although negligible in comparison with last week's Soviet accident, it was the first known major malfunction of a nuclear power plant.

Oct. 7, 1957. Like the Chernobyl facility, the Windscale Pile No. 1 plutonium-production plant north of Liverpool, England, used graphite to slow down neutrons emitted during nuclear fission. When workers discovered a fire in the reactor, they sprayed it with carbon dioxide but failed to quench the blaze. By the time the fire was put out with water, radioactive material had contaminated 200 sq. mi. of countryside. Officials banned the sale of milk from cows grazing in the area for more than a month. The government estimated that at least 33 cancer deaths could be traced to the effects of the accident.

- Jan. 3, 1961. A worker's error in removing control rods from the core of the SL-1 military experimental reactor near Idaho Falls caused a fatal steam explosion. Three servicemen were killed, one of them by impalement on a control rod. The deaths were the first fatalities in the history of U.S. nuclear reactor operations.

March 22, 1975. A worker using a lighted candle to check for air leaks at Browns Ferry reactor near Decatur, Ala., touched off a fire that damaged electrical cables connected to safety systems and allowed the reactor's cooling water to drop to dangerous levels. No radioactive material escaped into the atmosphere.

March 28, 1979. In the biggest U.S. mishap, one of two reactors at Three Mile Island, near Harrisburg, Pa., lost its coolant because of equipment malfunctions and human error. The loss of coolant caused the radioactive fuel to overheat and led to a partial meltdown. Some radioactive material escaped, but a potentially major disaster was averted. Although no one is known to have died as a result of the accident, the hazard posed to local residents is still being debated.

March 8, 1981. Radioactive waste water leaked for several hours from a tank at a problem-ridden nuclear power station in Tsuruga, Japan. The Workers dispatched to mop it up were exposed to radiation. The problem was not disclosed publicly until six weeks after the accident, when radioactivity was detected in a nearby bay.

Jan. 4, 1986. One worker at the Kerr-McGee Corp. uranium-processing plant in Gore, Okla., died from exposure to a caustic chemical that formed when an improperly heated, overfilled container of nuclear material burst. Some radiation flowed out of the plant, sending more than 100 people to local hospitals.