A cracking, 42-year-old concrete building that shields the steel containment vessel at Ohio’s Davis-Besse Nuclear Power Plant is finally receiving a weatherproofing protective coating.
|Painters are at work on the 250-foot-tall concrete shield building at Davis-Besse Nuclear Plant.|
Foes of the aging plant call the project “40 years too late” and say the coating cannot fix the structure’s cracks, which were discovered only last year.
Plant owner FirstEnergy Nuclear Operating Corp. disagrees, saying that the cracks do not affect the building’s structural integrity and that three coats of Sherwin-Williams’ Loxon should resolve any problems.
About 2,500 gallons of off-white paint will be needed to cover the 100,000 square feet of surface on the 250-foot-tall structure, FirstEnergy said. Painters are rolling on the coating from swing stages.
"They go up to the top of the building, and they apply the weather coating from the top to the bottom," says Bob Karr, project manager for First Energy.
Tim Ridlon, the company’s site coating specialist, said the product would protect the concrete from absorbing rain driven by winds of up to 98 miles per hour.
Jon Hook, design engineering manager at Davis-Besse, said the coating system features "certain characteristics that we want. It prevents moisture from going into the concrete. It's based for concrete masonry work. It's been tested and qualified for up to 100 mph."
The coating is designed to last 15 to 20 years.
The cost of the project is classified, officials said.
No Exterior Weatherproofing
The Shield Building, which has a critical safety function, was the only structure not coated before the plant went online in 1970. Officials said no coating was required at the time.
But the decision to skip the exterior weatherproofing left the building vulnerable to weathering that eventually caused the 2.5-foot-thick reinforced concrete structure to crack, FirstEnergy conceded in an analysis of the problem in the spring.
The Nuclear Regulatory Commission affirmed those conclusions in its own report in June. The agency recommended that FirstEnergy coat the structure.
Hook noted that the Shield Building was designed to protect the containment vessel. “The containment vessel is there for an accident, so there's no releases,” he said. “So the Shield Building is there to protect us from tornados, missiles, earthquakes and stuff like that.”
‘Very Tight’ Cracks
The cracks are believed to have originated with the Blizzard of 1978, when driving rain soaked into the concrete followed by plummeting temperatures that caused the moisture to freeze and expand.
The damage was not discovered until last October during an unrelated maintenance project. At the time, contractors were cutting through the structure to create an access hole to replace the reactor head, which had sustained a through-and-through hole caused by corrosion.
Crews discovered a hairline crack inside the wall, and further study revealed more extensive cracking in the concrete.
Hook said the crack widths “are very, very tight" and measure “approximately 'point-zero-one' inches."
The company said the coating would provide “another layer of safety.”
The coating work is expected to be completed by the end of September.
‘Not at All Comforted’
Environmentalists who are now fighting a 20-year extension of the plant’s operating license say the new coating does not allay their concerns.
The groups, including Beyond Nuclear, Citizens Environment Alliance of Southwestern Ontario, and Don't Waste Michigan, have urged regulators to deny the renewal for Davis-Besse when its license expires in 2017.
"I'm not at all comforted that they discovered an error that never should have happened to the most expensive and safety-significant building on the site," said Terry Lodge, a Toledo attorney representing the coalition.
Added Kevin Kamps of Beyond Nuclear, "It's 40 years too late. Weather sealant will not fix the cracks that are there."