NEWPORT, Mich. - Detroit Edison Co.'s Fermi II nuclear plant began producing electricity again early yesterday after a brief shutdown to address malfunctioning equipment. The boiling-water reactor plant in northern Monroe County was expected to be back at full power by last night, said utility spokesman John Austerberry.
The plant began its restart process at 10:30 p.m. Tuesday and was generating electricity again as of 1:20 a.m. yesterday, four days after operators had performed an instant shutdown because of a voltage drop caused by a faulty regulator.
Mr. Austerberry said the shutdown had no effect on safety, and the faulty voltage regulator has been repaired.
The rapid shutdown was performed manually by simultaneously inserting all control rods to halt the nuclear fission process. Under normal conditions, operators use a less-sudden technique to minimize stress on equipment, said Jan Strasma, Nuclear Regulatory Commission spokesman.
Fermi II operators followed NRC procedures by acting promptly, Mr. Strasma said, because the voltage drop gave them reason to question whether there could be complications with the more laborious method of inserting control rods in sequence, one by one. That would have resulted in a more gradual shutdown, he said.
“The important thing from our point of view is that the safety function was always there,” Mr. Strasma said.
The voltage problem was identified late Saturday, and the plant was shut down at 12:10 a.m. Sunday, while the plant was operating at 75 percent power. Workers repaired the regulator and did some routine valve maintenance that would have been performed at a later date, Mr. Austerberry said.
On Dec. 4, a solenoid in a turbine valve wore out. That problem was identified at 4 a.m., while the plant was operating at 91 percent power. About 101/2 hours earlier, at 5:30 p.m. Dec. 3, power had been reduced to 82 percent to inspect a nearby condenser circulation water pump that needed work.
A malfunction with one of those pumps Oct. 2 caused the reactor to shut down. Those pumps are in a non-nuclear section and help circulate water from the cooling towers through a condenser. The shutdown ended a 299-day operating streak, 39 days shy of the plant's 338-day record for continuous operation.