Donald C. Cook’s Unit 2 nuclear reactor is back in operation, one week after it shut down because of a steam line rupture.
The reactor returned to power at 6 p.m. Tuesday, spokesman Bill Schalk said.
On July 6, workers manually took the Bridgman, MI, reactor off-line after they discovered a steam line rupture.
Preliminary findings indicate the steam line ruptured due to “vibration-induced metal fatigue” of a steam expansion joint bellows, Schalk said.
Staff will redesign the equipment and make changes when the unit is shut down for a planned maintenance and refueling outage in the fall, he said.
“We’re working on that already,” he said. “We’ll either do something to reduce vibrations or strengthen the equipment.”
Metal parts ended up fabricated for the plant by its vendor before they could do the repairs, Schalk said.
The steam line leads to low-pressure turbines and released pressurized, high-temperature steam. The rupture damaged the wall of the turbine building.
Nuclear Regulatory Commission (NRC) inspectors assigned to the plant, and from the NRC’s regional office in Lisle, Ill, will independently evaluate the company’s response to the incident.