The Fermi 2 nuclear plant has restarted after engineers spent several weeks addressing excess levels of hydrogen in a generator cooling system.
The Nuclear Regulatory Commission indicated that the reactor resumed criticality Monday.
The Monroe News reported that the Detroit Edison plant shut down Nov. 7 following a rise in hydrogen levels in non-nuclear components at the plant. The gas is used as a coolant for one of the cooling systems of its main electrical generator. Although the generator was not overheating, a DTE spokesman told the newspaper, crews shut down the unit and inspected the generator as a precaution when elevated hydrogen was detected in its water-based cooling system. At that point, the plant had already been running at reduced power because of problems with a reactor feedwater pump in June.
According to the NRC, Fermi 2 is a General Electric type 4 boiling water reactor licensed in 1985.