Construction work on two nuclear power plants in the United States has been halted because of cost overruns, the companies behind them said. Santee Cooper, one of those firms, said that because of construction delays the two planned reactors in South Carolina could not come on line before 2024, four years behind schedule. This means only two nuclear plants are now in construction in the United States, in this case in Georgia, while there are about 100 up and running. The United States is the world's leading producer of nuclear energy but the sector accounts for less than 10 percent of total American energy production. The project in this case, called V.C. Summer, was launched in 2008 with Westinghouse, which had been acquired in 2006 by Toshiba. Westinghouse filed for bankruptcy protection in March of this year. Nuclear energy was popular in the 1960s and 70s in the United States but took a big hit with the accident at the Three Mile Island plant in Pennsylvania in 1979. No new plants have been added to the US nuclear grid between 1996 and 2016. The initial cost of the Summer project was put at around $11.5 billion but cost overruns doubled that because of construction delays and safety requirements. The other company involved in the project is South Carolina Electric & Gas (SCE&G). In a statement it said, "simply put, our evaluation showed that it would cost too much and take too long to complete construction on both units." "Although it appeared to us that it may have been feasible to complete construction of one unit, that option was eliminated when Santee Cooper decided to suspend construction of the project," SCE&G added. "It is not economically feasible for us to move ahead on our own, and the most prudent path forward is for SCE&G to cease construction of both units," it added.