WAYNESBORO, Ga. — The two nuclear reactors rising out of the red Georgia clay here, twin behemoths of concrete and steel, make up one of the largest construction projects in the United States and represent a giant bet that their cost — in the range of $14 billion — will be cheaper than alternatives like natural gas.
But something else is at stake with the reactors called Vogtle 3 and 4: the future of the American nuclear industry itself.
For Vogtle 3 and 4, the company submitted a license application with a design described as nearly complete and received an operating license when construction had barely started, contingent on building exactly what it said it would.
The older plants, in contrast, were built by welders and pipe fitters and electricians who were working from incomplete plans that were conflicting, vague or inadequate to meet regulatory standards.
In a second innovation, Southern chose a system in which large sections of the plant would be prefabricated in multiton sections, shipped to the site and welded together into gigantic modules, then loaded into place by the world’s largest crane.
But with construction now roughly one-third complete, it is clear that much is not going as planned, and that the schedule — which is closely linked to cost because of growing interest expense on the incomplete asset — has slipped by at least 14 months and possibly more.
But the company that was supposed to be making prefabricated parts like clockwork, from a factory in Lake Charles, La., was shipping them with some parts missing or without required paperwork. Southern built a cavernous “module assembly building,” 120 feet high and 300 feet long, where the parts were supposed to be welded together, largely by robots, into segments weighing thousands of tons. But shipments stopped last August and are still arriving too slowly.
The modules are just one problem. In the six-foot-thick basement of the plant, contractors painstakingly wove 1,200 tons of steel reinforcing bar together but connected the bars differently from the way the design specified. In the 1980s it would have made no difference, but today it requires a license amendment — a delay of seven and a half months.
Mr. Jacobs, the construction monitor, said delays could add hundreds of millions of dollars to the cost.
According to some staff members of the Public Service Commission, if there is no future tax on carbon dioxide emissions (which would raise the cost of alternatives) and if the price of natural gas stays low, the benefits of building the plant are razor-thin and could be eliminated by further delays and cost increases.