Three Mile Island - Unit 2

1.0 Site Identification

2.0 Site Status Summary

The Three Mile Island, Unit 2 (TMI-2) operating license was issued on February 8, 1978, and commercial operation was declared on December 30, 1978. On March 28, 1979, the unit experienced an accident which resulted in severe damage to the reactor core. (For details, see the Backgrounder on the Three Mile Island Accident.)

All spent fuel, including debris material that contains spent fuel, has been removed, except for some debris material in the reactor coolant system and ex-vessel (a total quantity of residual fuel is estimated to be less than 1125 kg or approximately 1 percent of the original core inventory). This debris material is primarily in the form of finely divided, small particle-size sediment material, resolidified material either tightly adherent to components or in areas inaccessible to defueling, and adherent films on surfaces contained within piping, tanks, and other components.

The removed fuel (TMI-2 debris) is currently in storage Idaho Nuclear Technology and Engineering Center (INTEC) on the Idaho National Laboratory (INL) Site, formerly known as the Idaho National Environmental and Engineering Laboratory, in Butte County, Idaho, in 10 CFR Part 72- specific Independent Spent Fuel Storage Installation (ISFSI) and the U.S. Department of Energy has taken title and possession of the fuel. TMI-2 has been defueled and decontaminated to the extent the plant is in a safe, inherently stable condition suitable for long-term management, similar to SAFSTOR where the facility would remain until decommissioning at some later time. This long-term management condition was termed post-defueling monitored storage (PDMS), which was approved in 1993. At that time, the license was changed to a Possession Only License (POL).

On October 27, 2025, TMI-2 Solutions submitted the TMI-2 Amended Post-Shutdown Decommissioning Activities Report. The Nuclear Regulatory Commission (NRC) staff is currently reviewing it for acceptability. TMI-2 Solutions is the licensee for Three Mile Island Station, Unit 2 and is authorized to conduct decommissioning of TMI-2 in accordance with NRC requirements and the TMI-2 License.

Environmental Review of Cultural and Historic Resource Impacts from Decommissioning Activities

On February 22, 2023, TMI-2 Solutions submitted a License Amendment Request requesting that the NRC review major decommissioning activities, as defined in 10 CFR 50.2, that would diminish the historic integrity (e.g., physical demolition) of the TMl-2 Solutions owned buildings previously deemed eligible for the National Register of Historic Places (NRHP) by the Pennsylvania State Historic Preservation Office (SHPO). The staff refers to this action as the Historic and Cultural License Amendment Request (LAR).  Physical demolition of the TMl-2 Solutions owned buildings previously deemed eligible for the NRHP could result in an environmental impact not bounded by the conclusions in the Decommissioning GEIS with regard to cultural, historic, and archaeological resources if appropriate mitigation is not developed in consultation with the SHPO. This LAR is intended to support applicable historic and cultural reviews regarding the TMl-2 owned NRHP-eligible buildings in anticipation of the eventual and necessary physical demolition of the facility to be performed in accordance with the TMl-2 decommissioning project schedule described in the Post-Shutdown Decommissioning Activities Report (PSDAR).

Decommissioning License Documents:

• The GPU Nuclear, TMI 2 Defueling Completion Report
• Order approving transfer of license and conforming license amendment, December 18, 2020
• License Amendment No. 67, March 31, 2023. This amendment eliminates certain technical specification requirements based on the current radiological conditions.
• Environmental Assessment (EA), August 1, 2024

3.0 Major Technical or Regulatory Issues

None

4.0 Estimated Date For Closure

2052