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Three Mile Island Nuclear Station, Unit 1

Life cycle timeline consisting of 6 various stages of status (Pre-Licensing, Licensing, Construction, Operating, Operating with Intent to Decommission, Decommissioning) with the current status(s) shown in color, and the other available status are greyed out hyperlink to Decommission section content for Pilgrim Nuclear Power station

Photograph of Three Mile Island 1

Location: Middletown, PA (10 miles SE of Harrisburg, PA) in Region I
Operator: Exelon Generation Co., LLC
Operating License: Issued – 04/19/1974
Renewed License Issued:  Issued – 10/22/2009
License Expires – 04/19/2034
Docket Number: 05000289

Reactor Type: Pressurized Water Reactor
Licensed MWt: 2,568
Reactor Vendor/Type: Babcock & Wilcox Lowered Loop
Containment Type: Dry, Ambient Pressure

Plant Diagram

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Operating with Intent to Decommission

Date Title
06/20/2017 Notification of Permanent Cessation of Power Operations

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Site Identification

Type of Site: Power Reactor Facility
Location: Middletown, PA
License No.: DPR-50
Docket No.: 50-289
License Status: SAFSTOR
Project Manager: Ted Smith

Site Status Summary

Three Mile Island Unit 1 (TMI-1) is located in the Susquehanna River near Middletown, PA, in Londonderry Township, PA,  10 miles southeast of Harrisburg, PA. TMI-1 is a facility with a Babcock & Wilcox pressurized water reactor nuclear steam supply system that was licensed to generate 2,568 megawatts – thermal (MWt).  Power operations ceased at TMI-1 on September 20, 2019, and that the fuel was permanently removed from the reactor vessel and placed in the spent fuel pool on September 26, 2019.  TMI-1 is preparing to construct an Independent Fuel Storage Installation (ISFSI).  TMI-1 is licensed to Exelon Generation Company, LLC (Exelon).

The Exelon decommissioning strategy for TMI-1 is SAFSTOR.  Exelon estimates that it will complete radiological decommissioning and release for unrestricted use to NRC requirements by 2079.  Exelon's decommissioning schedule is provided in their April 5, 2019, Post-Shutdown Decommissioning Activities Report (ADAMS Accession No. ML19095A041).

The NRC continues its oversight after the permanent shutdown of the facility to ensure the reactor is being decommissioned safely and that spent fuel is safely and securely stored onsite.  The NRC staff will periodically inspect operations at the site to ensure that decommissioning activities are being conducted in accordance with all applicable regulations and commitments.  The licensee is in the process of licensing and building an ISFSI which will eventually hold all the TMI-1 spent fuel casks.   Construction of the ISFSI is estimated to be completed by the end of 2021.  Exelon estimates that all the spent fuel will be transferred to dry storage onto the new ISFSI by the end of 2022.

Major Technical or Regulatory Issues

By letter dated June 20, 2017, (ADAMS Accession No. ML17171A151), Exelon notified the NRC of its intent to permanently cease operations at TMI-1 no later than September 30, 2019. By letter dated September 26, 2019 (ADAMS Accession No. ML19269E480), Exelon certified to the NRC that power operations ceased at TMI-1, and that fuel was permanently removed from the reactor vessel and placed in the Spent Fuel Pool on September 26, 2019. Accordingly, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.82(a)(2), the TMI-1 Renewed Facility Operating License (RFOL) no longer authorizes operation of the reactor or emplacement or retention of fuel in the reactor vessel.

The licensee plans to decommission TMI-1 independently of TMI-2 but may coordinate some decommissioning activities for shared facilities.

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Page Last Reviewed/Updated Friday, August 21, 2020