Last week's windstorm ripped large sheets of metal siding off the top of the reactor building at Energy Northwest's Columbia Generating Station, just weeks before work to shore up loose sections was scheduled to be completed.

There were no injuries from falling sheet metal and insulation loosened by Thursday's wind gusts that topped 60 mph at Hanford.

Energy Northwest spokesman Brad Peck said the siding is not critical to the 1,150-megawatt plant's nuclear safety defenses. The incident does not need to be reported to any of the public power consortium's regulators, though the Nuclear Regulatory Commission was notified, he said.

The top of the plant's reinforced concrete reactor building is circled by a ring of insulation and sheet metal siding that is about 65 feet tall. The south side of that ring typically is subjected to the strongest winds and repairs have been required from time to time since the plant commenced operation in 1984, Peck said.

Plans were made last fall to repair a portion of the siding that was coming loose toward the center of the south side. Late last month that work was scheduled to commence beginning the week of March 17.

But the windstorm beat work crews to it, removing a section near the vulnerable area and then the vulnerable area itself on the south side. A small amount of siding fell from the west side too.

"This issue of loose siding has been with us pretty much as long as the plant has been around," Peck said. "We've never had sheets of it 65 feet long falling on the ground where people sometimes walk. It's a real concern for us."

Workers in a crane-hoisted bucket have been fastening loose panels that remain. But Energy Northwest now plans to hire a contractor to replace the siding on all four sides.

No timelines for completion or cost projections have been developed.

"This is looking almost certainly like a rather large project," Peck said.