Exelon Generation on Friday pulled the plug on Three Mile Island Unit 1, which generated prodigious amounts of electricity for 45 years, but failed in the end to generate enough political support for its financial plight or its contribution as a carbon-free power source.
The 837-megawatt reactor, the elder sibling of the infamous reactor that was closed permanently in 1979 after a partial meltdown that set back the nuclear power industry, was disconnected from the regional power grid at noon Friday. The plant needed about 10 hours to cool down sufficiently so that the signature vapor plumes from its two cooling towers will disappear, a spokesman said.
"Today marks the end of an era in central Pennsylvania," said Mike Pries, a Dauphin County commissioner who was among the speakers who gathered outside the power station, at the plant's training center, to lament the closure. "It's a difficult day for the community, for the county and for all of central Pennsylvania."
The power station's workforce marked the occasion with a private ceremony inside the plant, know simply as "The Island" to insiders, said Dave Marcheskie, an Exelon spokesman.
On a day when young people across the world were staging protests to urge policy makers to take action on climate change, few noted that Three Mile Island's closure will increase Pennsylvania's emissions of greenhouse gases. Unit 1 produces more zero-carbon electricity than all the state's wind, solar and hydro plants combined, and it will likely be replaced by power produced from burning natural gas.
The state's nine commercial nuclear reactors at five sites produce 93% of the state's zero-carbon electricity.
The regional power grid is sufficiently large and diverse that Three Mile Island's closure will not affect reliability, according to the grid operator, PJM.
The company announced two years ago it planned to shut down Unit 1 unless the state came to the rescue of Pennsylvania's five nuclear power plants. Exelon said Three Mile Island lost hundreds of millions of dollars in competitive electricity markets dominated by low-cost natural gas.
When lawmakers were unable to generate support for a $500 million nuclear rescue package this year, which would have cost each state household about $1.77 a month in higher electric rates, Exelon announced in May that it would shut down the plant.
"This is a devastating loss," said Bart Shellenhamer, the fire chief and supervisor in Londonderry Township, where the Three Mile Island is by far the biggest taxpayer.