AEP Nuke May Be Offline Until 2010

American Electric Power Co. said on Monday that a unit at one of its nuclear power plants damaged in September will not return to full service until 2010. The company also estimated the cost of repairing and replacing the damaged turbine rotors in Cook Nuclear Plant’s Unit 1 at up to $332 million. AEP figures to recover most of the cost through insurance and warranties.

The unit at the plant in Bridgman, Mich., has been out of service since Sept. 20 after severe turbine vibrations damaged the main turbine and generator. The vibrations were caused by broken low-pressure turbine blades, the company said.

A repair option may allow operation at reduced power, but the rotors will ultimately be replaced to ensure the long-term viability of the unit. The expected return-to-service timeline ranges from the second half of 2009, if repair is successful, to 2010 if the rotors must be replaced before operation.

The best-case scenario, with successful repairs and expedited parts deliveries, could mean a return to service in September 2009. This repair option includes straightening the rotor shafts and modifying each rotor by removing one or two of the largest rows of blades until new rotors can be manufactured. Returning to service without one or two rows of blades would result in an approximate power reduction of 100 MW to 250 MW from Unit 1’s rated net capacity of 1,030 MW.

Work to straighten the first rotor shaft has started. Work on the third rotor will finish in mid-January.

If the repair is unsuccessful, the unit will not restart until new rotors are available. AEP and Siemens are pursuing turbine rotor replacement in parallel with repair. The manufacturing schedule of long lead-time items will result in a low-pressure turbine rotor delivery date and return to service in 2010.

The General Electric high-pressure turbine and main generator rotors are undergoing repairs at a GE facility in Chicago. Both are expected to be returned to Cook prior to the return of the repaired low-pressure turbine rotors.

Source: AEP