This summer, if all goes according to plan, the second reactor at Watts Bar Nuclear Power Plant will begin supplying power to the US electrical grid. Construction on the reactor in Spring City, Tennessee, has proceeded in fits and starts since the project began in 1973. It will be the first new nuclear reactor to come online in the US since the first Watts Bar reactor was completed 20 years ago.

The long delay in completing Watts Bar illustrates the challenges of constructing a nuclear reactor in the US. Construction on the project has been held up by public safety concerns, shifting regulatory expectations, fluctuating energy demands, and ballooning costs. The final price for Watts Bar 2 is currently projected to be $4.7 billion, a number which has been revised upward many times during construction.

Completion of the new reactor also comes at a complicated time for nuclear energy. The Fukushima disaster caused a brief halt in the development of new reactors around the world. Germany subsequently pledged to phase out nuclear power entirely. However, some countries, such as China and India, see nuclear as an essential part of their future energy mix.

Nuclear technology is also changing, with expanding global supply chains making the construction of new reactors look more like that of cars and other manufactured goods. The first prototypes of a new generation of smaller, cheaper, and more efficient reactors are just beginning to come online. Watts Bar has been especially criticized for relying on 1970’s technology similar to that of the Fukushima reactors.

It’s unlikely that completion of the project will encourage future nuclear projects in the US. If anything, the many delays and high cost may scare away future investment. Four additional reactors are currently under construction in the US, but if Watts Bar is any precedent, we may have to wait a very long time to see them connected to the grid.