EXPLAINER | Three Mile Island
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Three Mile Island

On March 28th, 1979 one of the reactors at the The Three Mile Island nuclear power plant near Harrisburg partially melted down. It marked the most serious accident in U.S. commercial nuclear power plant operating history.

The aftermath brought about “sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plant operations,” writes the Nuclear Regulatory Commission. “A combination of equipment malfunctions, design-related problems and worker errors led to TMI-2’s partial meltdown and very small off-site releases of radioactivity.”

The plant’s still operational Unit 1 reactor is now owned by Exelon, while the mothballed Unit 2 reactor is owned by FirstEnergy.

In May 2017, Exelon announced it would prematurely shut down the plant in September 2019—15 years before its license expires. The nuclear power industry has had a hard time competing economically amid slowing demand for electricity and a glut of cheap natural gas.

Both New York and Illinois recently agreed to give billions in subsidies to the nuclear industry by essentially broadening the definition of clean power. The states created so-called zero emission credits for their nuclear plants. There’s been a lobbying push to do something similar in Pennsylvania, but it has yet to gain traction.

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