In a classic "he said, she said" that might eventually affect customer bills, Georgia Power executives said they are in a dispute with Westinghouse and other vendors over who's responsible for $400 million worth of delays at the Plant Vogtle nuclear expansion project.

The consortium that includes Westinghouse and the Shaw Group -- makers of the twin 1,100-megawatt reactors at Vogtle -- has pegged $400 million worth of scheduling delays at the plant on Georgia Power. Utility executives are adamant that the opposite is true and assured the Georgia Public Service Commission at a hearing Wednesday that a settlement can be reached soon.

The chance that Georgia Power customers could wind up paying for the costs, however, worried some commissioners.

"What would concern me is if they bring an amendment and amend this and ask that the ratepayers pay for the $400 million," said PSC Chairman Tim Echols.

The reactors were scheduled to start producing power in April 2016 and April 2017. With the delays, they would start operating later in those years.

Georgia Power's parent, Atlanta-based Southern Co., outlined the dispute in a quarterly filing with the U.S. Securities and Exchange Commission earlier this week.

"If it’s deemed that the company has responsibility and has cost obligations, we’d come back to this commission," testified David McKinney, vice president of nuclear construction and support for the Vogtle expansion project. "We understand that no cost can be passed on to our customers without approval of this commission."

Georgia Power is responsible for $6.1 billion of the estimated $14 billion project, which is the first newly permitted reactors in 30 years. The first two reactors at Vogtle were plagued by a series of cost overruns and scheduling delays, some tied to increased safety regulations after Three Mile Island, others because of what was deemed project mismanagement.

State utility regulators now must review and approve the project's costs every six months to head off any major problems. For its part, Georgia Power must signal any changes to the schedule or cost, regardless of whether they would impact the overall budget in the end.

Meanwhile, company executives touted saving customers $2 billion because of low interest rates and a combination of tax breaks and other incentives.

Southern continues to negotiate with the Department of Energy over the conditions of $8.3 billion in loan guarantees that the agency awarded the project. Should Georgia Power not agree to the DOE's new terms and decide not to accept the loan guarantees, customer bills would not increase, a company spokesman said.