NRC sends team to Ohio Davis-Besse reactor

NEW YORK, March 18 (Reuters) - The U.S. Nuclear Regulatory Commission sent a special inspection team to FirstEnergy Corp's (FE.N) 879-megawatt Davis-Besse nuclear power plant to look into indications of cracks in multiple reactor vessel head nozzles.

The NRC said there was no danger to the public from these cracks since the plant has been shut for scheduled refueling. Before the plant can resume operations, the NRC said it must be satisfied the problem has been addressed.

Earlier this week, FirstEnergy could not say whether the repairs would add to the length of the refueling outage.

Before news of the needed vessel head repairs, electricity traders had guessed the unit, which shut on Feb. 28, would return in early April. The reactor last shut for refueling from about Dec. 31 to Feb. 15, 2008. It is on a 24-month refueling cycle.

Last week, workers discovered indications of cracks in some of the control rod drive mechanism nozzles, which the control rods into the reactor core to shut the reactor. The inspection of the 69 nozzles is ongoing.

The NRC said it was concerned because a crack in the nozzles, which penetrate the reactor vessel head could lead to structural damage of the reactor head, which prevents radioactive material in the reactor from escaping into the plant containment building.

Davis-Besse shut from 2002 to 2004 to fix a football-size hole in the six inch reactor vessel head caused by boric acid from severe cracks in the nozzles. That cost FirstEnergy about $600 million plus several million more in fines and other monies paid to federal, state and local authorities and organizations.

At this time, the NRC said there was evidence of a very small amount of what appears to be boric acid residue (roughly one cup) near two of the nozzles.

FirstEnergy hired nuclear contractor AREVA SA CEPFi.PA to fix the vessel head.

FirstEnergy acquired the vessel head from a partially completed nuclear reactor in Midland, Michigan. It was unused when the company acquired and installed it during the 2002 to 2004 outage.

Davis-Besse is located in Oak Harbor in Ottawa County about 35 miles (56 km) east of Toledo, Ohio. (Reporting by Scott DiSavino; Editing by John Picinich)