Three Mile Island nuclear plant

Plumes of water vapor billow from the cooling towers tied to the active Unit 1 reactor at the Three Mile Island nuclear plant.

1. What's happening and why?

Exelon announced Wednesday morning it will shut down Three Mile Island by Sept. 30, a possibility it first disclosed two years ago. The nuclear power plant loses hundreds of millions of dollars a year. Exelon, which is profitable overall, says significant subsidies or policy changes would be needed for TMI to be economically viable. 

A rescue plan was proposed that would have subsidized Pennsylvania's nuclear industry to the tune of about $500 million a year, but it has not advanced in the state legislature.

2. How many jobs are affected?

About 675 people work at TMI, of whom about 200 live in Lancaster County Exelon said it will offer positions to employees who are willing to relocate. Staff at TMI will be reduced to 50 full-time workers by 2022.

3. What does this mean for electricity consumers?

TMI's closure will have no impacts on service reliability, according to PJM Interconnection, which manages the mid-Atlantic's grid. Neither PJM nor PPL Electric Utilities, which distributes electricity in central Pennsylvania, would comment on price.

Had the nuclear industry bailout plan been enacted, Pennsylvania's rates would have gone up. The plan's sponsor estimated it would raise typical residential rates by $21.24 a year. The Office of Consumer Advocate, a state agency, said the increase would be about $35 a year. 

4. How will the closure impact local communities?

Exelon estimates TMI's economic impact on its surrounding area to be $3.5 billion since 2000, counting wages, taxes and purchases from local vendors. TMI pays property taxes in Londonderry Township, Dauphin County, and supports the local volunteer fire department there. Its workers pay taxes in their home communities.

5. What happens next?

Once TMI shuts down, staff will be reduced to about 300 by March and 200 by 2021. The fuel rods will be removed from the reactor but will remain on-site until 2034 or 2035. Exelon won't begin dismantling the site until 2074.

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