Three Mile Island pictured on June 3, 2024. (Jeremy Long – WITF)

The owner of the Three Mile Island nuclear plant is beginning a review of how restarting power operations will impact the environment.

The federal Nuclear Regulatory Commission in a public meeting Thursday told Constellation representatives they should be as detailed as possible in their environmental review to ensure a smooth permitting process.

Constellation is planning to restart the Unit 1 reactor, which opened in 1974 and shut down in 2019 for economic reasons. Now the company has a deal with Microsoft to supply carbon-free power to its data centers in the region, giving the plant new life. Constellation has said it wants the plant running again by 2028.

To resume power generation, Constellation needs to conduct an environmental review, which involves analyzing how the plant’s operations will impact areas such as water quality, air quality and wildlife habitat. The company must also include mitigation measures for potential impacts.

TMI Unit 1 last had its operating license renewed in 2009. At that time the NRC concluded the renewal would have small impacts.

Craig Smith, a regulatory assurance manager for TMI Unit 1, said they’re not planning any major demolition or building construction projects that could disturb land. They will need to replace an underground diesel fuel tank.

Jill Caverly, environmental project manager for the NRC, said her advice is to think of any land that may be disturbed by even small projects and to create an extensive list of any permits that will be required to restart the plant.

She said impacts will be defined as the difference between what is the current status of the site and how it will change as power operations resume.

Allison Stalker, environmental lead for TMI’s restart, said there are several major permits the site needs to operate.

The site currently has a National Pollution Discharge Elimination Systems permit for wastewater entering the Susquehanna River. The company recently submitted a renewal application to reflect changes under the restart.

TMI Unit 1 also holds a Susquehanna River Basin Commission docket that approves water withdrawal from wells and the Susquehanna. Stalker said they plan to apply this July for a new docket to increase water withdrawal upon operation.

TMI Unit 1 also needs to obtain an air quality permit and a certification under the Clean Water Act.

Stalker said they will likely ask the NRC to audit their environmental report before officially submitting it for evaluation. The company hopes to submit that report in October.

The environmental report is just one piece of the overall application Constellation must submit to the NRC. The company must also turn in plans for emergency response and plant security.

TMI Unit 1 is one of only three nuclear plants in the country attempting to restart after shutting down. The others are Palisades in Michigan and Duane Arnold Energy Center in Iowa.

The TMI Unit 2 reactor partially melted down in 1979 and never came back online. The accident was the worst at a commercial nuclear site in the country. The reactor is now owned and is being cleaned up by a subsidiary of Utah-based EnergySolutions.