Final answer:
The most damaging nuclear power plant accident occurred at Three Mile Island, USA. The accident occurred in 1979 and resulted in a near disastrous core meltdown, although no deaths or cases of cancer were reported. It led to stricter regulations and a decline in new nuclear plant construction.
Step-by-step explanation:
The most damaging nuclear power plant accident occurred at Three Mile Island, USA. In 1979, a near disastrous core meltdown occurred at the Three Mile Island nuclear power plant in Pennsylvania. Although the accident did not result in any deaths or cases of cancer, it had significant impacts and led to tougher industry regulations and a decrease in the construction of new nuclear plants.