The Nuclear Regulatory Commission on Wednesday greenlighted the transfer of Three Mile Island’s Unit 2 license to EnergySolutions subsidiary TMI-2 Solutions from FirstEnergy Companies for decommissioning. 

Three Mile Island’s Unit 2, located 10 miles from Pennsylvania’s capital city of Harrisburg, shut down in 1979 after its core partially melted down in the biggest accident in U.S. nuclear plant history.

A pressure valve at the reactor failed to close, causing radiation-contaminated water to drain into nearby buildings, prompting the reactor’s core to overheat. Some workers were exposed to unhealthy levels of radiation, but no one outside the plant was sickened by the accident. After the accident, almost all of the reactor’s fuel and damaged core material was sent to the Department of Energy’s Idaho National Laboratory.

EnergySolutions announced the company had signed a contract with FirstEnergy to acquire the reactor in October 2019. The public had the chance to comment on the transfer earlier this spring. 

Two of the loudest voices of dissent during the public comment process came from Pennsylvania’s Department of Environmental Protection and a citizen’s advocacy group called “Three Mile Alert.” Both groups expressed concern over TMI-2 Solutions’ ability to finance the decommissioning. 

The reactor has been in “safe storage,” or SAFSTOR, mode, which can delay completion of decommissioning by up to 60 years. Now that the Unit 1 reactor has closed, the site is able to start undergoing decommissioning. Unit 1, owned by Exelon, shut down in September 2019. 

TMI-2 plans to spend around $1.06 billion to decommission the reactor by 2037.