Ford].

Then, 23 years later, when Unit 2 at the Three Mile Island power plant in Pennsylvania suffered a cooling malfunction and a partial meltdown of its radioactive fuel, feelings about reactors changed radically. Even though the stricken reactor's containment held and there was no major radiation release, many people began to see reactors as overly complicated and vulnerable to human and equipment failures, with potentially catastrophic consequences. They also worried about the radioactive waste from reactors. Worse yet, many wondered if government regulators and the nuclear power industry were leveling with the public. As a result, the construction of new nuclear plants stopped in the United States. When a more serious accident occurred at the Soviet Union's Chernobyl nuclear plant in 1986, nuclear power seemed doomed to obsolescenceand experience a meltdown. With a meltdown, the fuel turns to liquid and then burns through the containment vessel, spewing radiation far and wide. In 1979, Three Mile Island's Unit 2 came perilously close to this scenario, with the core partially melting down and flowing to the floor of the containment vessel. Fortunately, as scientists later discovered by lowering a camera into the unit, the well-designed containment was strong enough to stop the radiation from getting out [source: Smithsonian].

The Soviets had worse luck. The worst nuclear accident in history was the April 1986 catastrophe at Unit 4 of the Chernobyl nuclear plant in the then-USSR, which was caused by a combination of system breakdowns, design flaws and badly trained personnel. During a routine test, the reactor suddenly surged,