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.

The Alvin W. Vogtle nuclear power plant near Augusta is using a new plant design, a new construction method and a new system of nuclear regulation for what the industry says is a faster, better and cheaper system that will lead the way for a new generation of reactors.

Until recently, a new reactor construction project had not been started in the United States for 30 years, and now Vogtle and a similar project in South Carolina, V.C. Summer 2 and 3, are supposed to provide the answer to nuclear power’s great questions: What does a new reactor cost? With the price of natural gas near historical lows, can it even be worthwhile?