The issue surfaced in April, when federal inspectors determined that the manner in which pieces of rebar were connected differs from specifications approved for the Westinghouse AP1000 reactors being built at the Burke County site.
Southern Nuclear proposed modifying the rebar that was already in place, but the idea was rejected by NRC staff.
Last week, the company proposed a new solution in which the compressive strength of the nuclear concrete to be poured around the rebar would be increased – from 4,000 pounds per square inch to 5,000 pounds per square inch.
That change, according to the company’s request, would give the structures the desired resistance to seismic activity and bring it into full design compliance.
Regulators responded in a letter dated Friday that Southern Nuclear will be allowed to proceed – at its own risk – with the plan to use stronger concrete while the NRC evaluates the formal request for a license amendment.
If the request is later denied, however, Southern Nuclear will have to go back and “return the plant to its current licensing basis,” the letter said.
The $14 billion expansion includes two new reactors near the site’s two existing units. The new units are scheduled to go online in 2016 and 2017.