Nuclear, Reactors

Davis-Besse nuclear station extends refueling outage after corrosion found


By Sylvie Dale, Online Editor

March 13, 2002 — FirstEnergy Nuclear Operating Co. (FENOC), a subsidiary of FirstEnergy Corp., announced Wednesday it expects the refueling and maintenance outage for the Davis- Besse Nuclear Power Station to be extended by 60 to 90 days, although the exact length of the outage has not yet been determined.

Federal inspectors from the Nuclear Regulatory Commission (NRC) last week found boric acid corrosion in and around one of the nozzle penetration holes, which created a 6-inch hole in a steel cap covering the reactor. While inspectors said this was the worst corrosion ever found on top of a U.S. nuclear reactor, the discovery does not pose a safety threat.

Originally scheduled to return to service by the end of March, the plant, located in Oak Harbor, Ohio, will remain off line while crews complete repairs on the reactor head. In addition to the corrosion repairs, the crew will also repair five Control Rod Drive Mechanism nozzles.

Trace amounts of boric acid are believed to have leaked from at least one of 69 control rods’ nozzles, and the acid came within a half-inch of burning a hole through the vessel head. It burned through the outer layer of the reactor head and made contact with steel on the cap, but that form of steel was impervious to boric acid and was not damaged.

As plant officials continue to investigate the cause of the problem, they are providing information to the Nuclear Regulatory Commission’s (NRC) Augmented Inspection Team, composed of metallurgical and engineering specialists who arrived on site Tuesday.

In addition to monitoring the investigation, the NRC will review and approve the final plan for repairing the corrosion problem. Information from the investigation will help regulators and other plant operators determine if similar conditions might exist at other plants.

FirstEnergy has said it will replace the reactor head on the facility’s next shutdown, scheduled for 2004.

Supplemental information is included in a March 13, 2002, letter addressed to the investment community that will be posted on the Investor Relations home page at FirstEnergy’s Internet site: www.firstenergycorp.com/ir .