24 October 2008 — Initial inspections and disassembly of the main turbine are complete at American Electric Power’s 1,030 MW Cook Nuclear Plant Unit 1, out of service since Sept. 20 after vibrations — likely caused by a broken low pressure turbine blade — damaged the main turbine.
The turbine rotors and other major components have been shipped to the original manufacturers for engineering analysis and repair.
AEP expects to have a return-to-service schedule and cost estimates for the nuclear power unit by late November.
The vibration also caused a hydrogen leak, resulting in a fire in the main generator that caused minimal damage to the facility, which is located in Michigan.
Cook Unit 1 has three low-pressure turbines manufactured by Siemens and one General Electric high-pressure turbine and main generator.
The low-pressure turbine rotors, casings and other support equipment were shipped to the Siemens turbine facility in Charlotte, N.C., to determine whether the components will be repaired or replaced.
The high-pressure turbine rotor was shipped to a General Electric facility in Chicago and is undergoing similar assessments.
Disassembly of the main generator is also complete. The generator rotor will be shipped to the GE facility in Chicago for testing and repair.
Initial electrical testing of the generator rotor and stator has not detected any major issues. Generator parts, such as high voltage bushings and current transformers damaged during the event have been ordered.
At the site, AEP personnel have developed a schedule for the remaining inspections and completion of repairs on other plant equipment such as associated turbine piping and insulation, turbine bearings and turbine plant motors and pumps.
In addition, cleaning of broken insulation in the turbine building, water from fire suppression and oil released from the turbine lube oil system during the event will be done. The oil was contained within plant systems during the event resulting in no impact to the environment.
Siemens and GE are working to deliver parts and perform repairs. Once parts delivery and repair estimates are completed, they will be integrated into the plant schedule and AEP will release a return to service timeline and total cost estimate.
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