Standard&Poor's Ratings Services notes that Dominion Resources Inc.'s North Anna nuclear power station, Unit 2 (NA II), was returned to full power on Feb. 2 after replacing the unit's reactor vessel head. The relatively quick turnaround on the replacement of the vessel head bodes well for an industry that is likely to continue to face vessel head replacement problems going forward. Dominion used a scheduled refueling and maintenance outage, which began in early September 2002, to conduct the replacement. The refueling outage was extended after inspections of the original vessel head found minor indications of leakage in the welds that attach control rod drive guide and instrument tubes to the head. The replacement foreshortens the previously scheduled replacement
