Monday, April 27, 2009

Small hole not the first found at Shippingport’s nuclear power plant

The affected area was last inspected in 2007 during another maintenance outage, Schneider said, and no problems were found then, so the corrosion occurred within the last couple of years. Sheehan said that in 2006, inspectors found a small area of corrosion that was repaired. Then, Sheehan said, it was ruled that moisture trapped between the concrete and the liner caused the corrosion. Schneider said Saturday that in the 2006 discovery, the corrosion didn’t eat all the way through the barrier. “We’re always interested in trends,” Sheehan said of Thursday’s discovery. “If this says something about any systemic corrosion, we would want to know about that.” The corroded steel will be removed, Schneider said, and another piece of steel will be welded into place. The removed steel will be examined to try to determine what caused the damage. The Cleveland Plain Dealer reported Friday that a coolant leak in the lid of FirstEnergy’s Davis-Besse nuclear power plant near Toledo was undiscovered for several years. That allowed corrosion, which was accelerated by boric acid, to eat through a 6-inch-thick carbon steel lid. The acidic vapors also caused corrosion problems in gear and paint throughout the containment building at Davis-Besse. Schneider said that the Shippingport corrosion was not caused by boric acid, which is added to reactor coolant. Schneider would not say how long the reactor will remain offline for its scheduled maintenance, but said Thursday’s discovery won’t delay the reactor restart; the repair to the steel will proceed during the refueling and maintenance work.
Beaver County Times

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