While it still remains a mystery why small cracks appeared in a concrete shell that protects the nuclear plant, inspectors are certain the nuclear reactor along Lake Erie is safe to operate.
Tests on the concrete have not given inspectors any reason to keep the plant shut down, said Cynthia Pederson, a regional director with the U.S. Nuclear Regulatory Commission (NRC) who oversees plants in the Midwest.
“We have a very vigorous inspection we did and it’s still ongoing,” Pederson told concerned citizens during a public meeting near the Davis-Besse nuclear plant, which is just outside Toledo. “There is a high-level of assurance the containment building is safe.”
The NRC allowed the Davis-Besse nuclear plant to begin producing electricity again in early December, less than two months after finding the first cracks.
The plant shut down for maintenance in October when crews discovered a 30-foot hairline crack in the outer concrete wall designed to protect the reactor from anything that might hit it from outside, such as storm debris or an airplane. Officials found more cracks soon after near the bottom of the 224-foot tall shield structure, leading to closer inspections that found cracks close to the top of the wall.
The commission signed off on restarting the plant following several tests and after its owner, FirstEnergy Corp., assured it the cracks don’t pose a threat.
The commission has given Akron-based FirstEnergy until the end of February to find out what caused the cracks.
It’s possible that the cracks have been around for a while, she said. “Concrete has a tendency to crack,” Pederson said.
Davis-Besse shut down this fall to replace an 82-ton reactor head, a steel lid that sits atop the reactor vessel.
FirstEnergy said the new reactor head is made of better material than the former reactor lid that had cracks in its nozzles.
The plant also shut down from 2002 to 2004 because of an acid leak in a different reactor head.
Regulators fined FirstEnergy $5.45 million and the company agreed to $28 million in civil penalties following what the NRC said was the most extensive corrosion at a U.S. nuclear reactor. The NRC said FirstEnergy misled the agency by providing incomplete and inaccurate information about the acid leak.