Former US reactor site released for unrestricted use

Zion, on the shores of Lake Michigan, was home to two pressurised water units: unit 1 operated from 1973 until 1997; unit 2 from 1974 to 1996. Both were declared permanently shut-down in 1998 by the plant's operator at the time, Commonwealth Edison (part of Exelon). In 2010, the reactor's licences were transferred to EnergySolutions subsidiary ZionSolutions in a first-of-its kind arrangement for accelerated decommissioning. The Zion units are now part of Constellation Energy's portfolio since the separation of Exelon Generation's regulated and competitive energy businesses.

The way we were: Zion's two units operated until the late 1990s. (Image: NRC)

Releasing the site for unrestricted use means that any residual radiation is below NRC's limits and will no longer be under NRC regulatory controls, the regulator said. The NRC's determination that ZionSolutions has satisfactorily finished decommissioning of the plant and decontamination of the site to meet the agency's radiation protection standards clears the way for ZionSolutions to transfer the spent fuel storage facility licence to Constellation Energy Generation, which will be responsible for the security and protection of Zion’s spent fuel facility until an offsite storage facility or permanent disposal site becomes available.

According to Constellation, the USD1 billion, 10-year project to decommission the Zion plant is the largest commercial nuclear plant dismantling ever undertaken in the USA.

Constellation is free to use the remainder of the former plant site for any application, the NRC said.