Site Facts
Site Location:
Constellation Energy Generation LLC
2625 River Road
Middletown, PA 17057-0480
Previous Property Owners/Operators:
- Metropolitan Edison Company
- General Public Utilities (GPU)
- GPU Nuclear Corporation
- FirstEnergy Corporation
- Exelon Generation (later Constellation Energy Generation)
Current Property Owner/Operator:
Constellation Energy Generation, LLC
(Following separation the spin-off from Exelon in 2022)
Point of Contact:
Media or Community Relations – Nuclear Operations
Address:
Constellation Corporate Headquarters:
1310 Point Street Baltimore, Maryland 21231
Constellation Satellite Office:
200 Exelon Way, Kennett Square, PA 19348
Phone:
667-218-7700 (Media Hotline)
Historical Uses of the Property:
1968–1974: Site Preparation and Construction of Nuclear Power Plant
1974–2019: Commercial Operation of Nuclear Reactors (Unit 1 operational; Unit 2 damaged in 1979)
1979–2021: Unit 2 Cleanup and Storage Following Partial Meltdown
July 1998: Unit 1 sold to a predecessor company to Constellation Energy Generation, Unit 2 remains in ownership of General Public Utilities Corporation.
2019–2024: Decommissioning of Unit 1; Long-term Site Monitoring and Radioactive Waste Storage
December 2020: Unit 2 sold to TMI-2 Solutions, a wholly owned subsidiary of Energy Solutions, to manage long-term cleanup of the facility.
2024-Present: Pursuing permitting at Nuclear Regulatory Commission for a license to extend operations to at least 2054, as well as permits from state and local agencies.
Historical Information
On March 28, 1979, Unit 2 at Three Mile Island suffered a partial meltdown. The facility, which is owned by TMI-2 Solutions, a wholly owned subsidiary of Energy Solutions remains in a monitored storage state. Unit 1 continued to operate safely until it was permanently shut down on September 20, 2019.
What is Currently Planned
In September 2024, Constellation Energy announced it had signed a 20-year power purchase agreement with Microsoft. Constellation will restart Unit 1, which was renamed the Crane Clean Energy Center (CCEC). The plant will generate 835 megawatts of carbon-free energy. Microsoft will purchase the energy generated at the renewed plant.
What is the U.S. Nuclear Regulatory Commission?
The U.S. Nuclear Regulatory Commission (NRC) is the federal agency responsible for overseeing the nation’s civilian use of nuclear materials to ensure the protection of public health, safety, and the environment. At Three Mile Island, the NRC has overseen all aspects of the site’s decommissioning process. It will also regulate its planned reopening. This includes evaluating license amendments, safety protocols, radioactive waste management, and long-term site monitoring. Any plan to restart nuclear operations or redevelop the site would require NRC review, public hearings, and regulatory approval.
What is the Pennsylvania Department of Environmental Protection’s Involvement in This Proposed Project?
The Pennsylvania Department of Environmental Protection (DEP) has played a regulatory role in the site’s decommissioning. It will also play a role in the effort to reopen the site by ensuring compliance with state environmental laws. DEP will review permit applications, conduct environmental impact assessments, and work in coordination with the NRC to protect public health and the environment. DEP is also the certifying agency under Section 401 of the Federal Water Pollution Control Act (“Clean Water Act”). Section 401 requires a state water quality certification for any federal license or permit that may result in a discharge into navigable waters of the United States. This certification ensures that the proposed activity will comply with state water quality standards.
What Permit Applications is DEP Expected to Receive and Review?
The NRC will oversee the licensing process, reactor safety, radioactive material management, operator training, emergency preparedness, and public engagement. DEP will review and enforce state-level permits related to air and water quality, waste disposal, and other environmental impacts.
Here is a list of permits the DEP either has, or expects to receive applications for in regard to this project:
Currently the site is classified as a generator of hazardous and residual waste. Hazardous and residual waste are types of industrial waste—hazardous being harmful or toxic, and residual being non-toxic byproducts—and it's common for factories, power plants, and other industrial facilities to produce one or both during their operations. This waste generation would not require a permit as long as generator regulations for handling, storage, and disposal are followed.
The DEP Safe Drinking Water Program and the applicant are negotiating a Consent Order and Agreement (COA) to address the Per-and-polyfluoroalkyl substances (PFAS) also known as “forever chemicals” that have been found in both of the facility’s wells. Per the regulations, the exceedance of the PA Maximum Contaminant Levels (MCL) for PFAS in the wells is categorized as a “significant deficiency.” Constellation has 120 days from when it was notified (Feb. 25, 2025) to correct the deficiency or have a DEP-approved plan to address the deficiency. Because the permitting and construction of PFAS removal treatment will take longer than 120 days, the COA will be used to memorialize the approved corrective actions needed to address the violation and bring Constellation into compliance with the Safe Drinking Water Regulations. The COA does not contain any civil penalty assessment for the violations but does have standard stipulated penalties for missing agreed-to deadlines in the plan.
The site will need to update its Water Quality Management (WQM) permits if any changes are proposed. This permit is required before building or changing any system that handles sewage or industrial wastewater, to make sure it’s designed to protect water quality and public health.
The site currently has an administratively extended National Pollution Discharge Elimination System (NPDES) permit. An NPDES permit will allow Constellation Energy Generation to legally release treated water or wastewater into rivers, lakes, or other waterways, while ensuring it meets environmental safety standards. The site will need an updated NPDES permit for wastewater discharge.
The site will need to request a Water Quality Certification (WQC). The WQC request evaluates the project’s overall compliance with state water quality standards. Under the Clean Water Act, the WQC is required prior to the issuance of the license amendment to restart the facility and is also incorporated into the federal license amendment.
The site will need to obtain water obstruction and encroachment (WO&E) permits for any water obstruction and encroachment activities in regulated waters of the Commonwealth. Examples include new construction of or maintenance of existing intake or outfall structures or the construction of or modification of bridges.
If earth disturbance activities of one acre or more are proposed, the site will need to obtain a NPDES Construction Stormwater permit to manage erosion and sedimentation in runoff during any construction activities, and to manage stormwater during post-construction operation of the site.
Previously issued air quality permits have not been renewed. DEP would need to evaluate permits required based on the proposed equipment and uses. This has yet to be determined.
Community Outreach and Office of Environmental Justice
- DEP has maintained a history of engaging Pennsylvania residents on environmental justice by administering its constitutional, statutory, and regulatory duties. It will continue to proactively engage communities living in EJ areas, including during environmental emergencies, public complaints, new project proposals, and the operation of existing facilities.
- In an effort to build and maintain relationships with EJ communities outside of individual projects or emergencies, the Shapiro Administration has directed DEP to increase proactive outreach and engagement. OEJ’s proactive outreach and engagement is focused on community education with an emphasis on plain language, public notice, and capacity building to foster meaningful access, engagement, and intentional action.
How Might This Affect You and Environmental Health Concerns:
The project would have significant implications for the surrounding community and the commonwealth. Making use of new energy generation assets and technical expertise will create jobs, provide economic benefits which include support for local businesses and potential tax revenue, while positioning Pennsylvania to remain competitive in the energy market. Oversight would supply a more efficient permitting process and encourage community engagement to address the needs and concerns of the public.
Media Contact
DEP Media Inquiries:
John Repetz
Regional Communications Manager Supervisor
717-787-1323 or jrepetz@pa.gov
Health Information
Pennsylvanians that have environmental health related questions can contact the PA Department of Health (PA DOH), where they will be evaluated and referred to an appropriate program area for potential investigation and follow-up.
Complete the Environmental Health Concern Form
Phone: 717-787-3350