Plant Vogtle’s expansion is not likely to meet its current construction deadlines, according to Georgia Public Service Commission staff analysis released Friday.

Vogtle, in Waynesboro, Georgia, is the only nuclear power plant under construction in the country. It is at nearly double its original budget and five years behind schedule. The company set a new baseline schedule last spring, which commission staff is calling over-aggressive and unachievable.

That schedule features a completion date range of May to November 2021 deadline for Unit 3 and May to November 2022 for Unit 4. Commission staff consultant Don Grace said the May dates “cannot be achieved,” and that “unless performance improves significantly,” the November dates “are significantly challenged.”

In testimony earlier this month, Stephen Kuczynski, president of Southern Nuclear, said meeting these deadlines would be “a challenge, but achievable.”

Grace wrote the main reason the schedule is “unreasonable” is that it’s taking workers longer to complete tasks than the company has assumed in its plans. Something, he said, that wouldn’t necessarily be solved by hiring more people: “when continuing to simply add labor, you get to a point where more craft is unproductive and not conducive to completing work in an efficient and timely manner.”

Grace explained the staff predicts Unit 3 will be done in February or March of 2022 if nothing changes, but could not predict Unit 4’s schedule. However, he did note the staff finds it “aggressive” that a second unit would be complete one year after the first, noting Vogtle Unit 2 finished two years after Unit 1.

Regarding cost, Grace said if “current performance trends continue,” the total budget set for the project’s construction, $17.1 billion, “may be exceeded.” Including financing costs, the project’s total budget has come to more than $25 billion.

Georgia Power owns just under half of the project. The rest of ownership is divided among MEAG Power, Oglethorpe Power Company and Dalton Utilities.

In separate testimony, commission staff member Tom Newsome and consultant Philip Hayet noted the total delays on the project based on the November 2022 schedule would cost ratepayers an extra $1.8 billion, or about $385 per typical residential customer, just in the additional funds collected by the Nuclear Construction Cost Recovery tariff. They also argued that a delay past 18 months of the November scheduled could mean the project would be “uneconomic to continue.”

Meanwhile, on Friday, Southern Company celebrated a construction milestone for the project: the installment of the final containment ring on Unit 4. Containment vessel rings are part of the buildings which will hold new nuclear reactors.