Although a formal, written report that would outline corrective options is not due until May, federal regulators have already met with Southern Nuclear executives to advise them of the finding, said NRC spokesman Roger Hannah.
“We had a meeting onsite with their management to preliminarily identify this as an issue,” he said. “It is preliminary information and at this point we don’t identify the severity of the issue.”
The rebar, installed at the Unit 3 construction site, is part of the basemat that forms the “nuclear island” upon which the reactor and other components will rest.
Inspectors determined the manner in which pieces of rebar are connected to increase strength differs from design specifications approved for the Westinghouse AP1000 reactors being built at the Burke County site.
Hannah said the discrepancy doesn’t mean conclusions have been drawn as to whether the different method of joining rebar is better or worse than design standards.
“Those determinations would be made later,” he said. “Our inspectors identified it as a design change that had not gotten prior approval from NRC.”
Although regulators did not order a halt to further installation of the rebar, Southern Nuclear made a decision not to continue that portion of the work until there is some sort of resolution, he said.
So far, about 35 workers have been idled.
The matter was addressed briefly this week by Southern Company Chairman and CEO Tom Fanning, during an earnings conference call with analysts.
“We expect to receive official notice of this finding from the NRC,” Fanning said. “In the meantime, we are engaged in constructive discussions with the consortium to identify appropriate action. We can reasonably expect to encounter additional inspection issues between now and the time the new units are completed as they are a normal part of the nuclear construction process.”
One possible resolution is for Southern Nuclear to apply for a license amendment to allow the non-conforming rebar to remain in place, Hannah said. Such a request could be honored only if NRC staff reviewed the issue and concluded it would meet accepted standards.