Exelon Threatens to Close Two Nuclear Plants in Illinois (2)

Exelon Corp. is threatening to close two nuclear power plants in Illinois next year and is warning that two others may also retire early, after regulators changed rules in the biggest U.S. power market.

The company said its “uneconomic” Byron plant west of Chicago will close in September 2021 and the nearby Dresden plant will follow two months later, according to a statement Thursday. Exelon’s LaSalle and Braidwood sites “are also at high risk for premature closure.”

The company said the move is a response to the Federal Energy Regulatory Commission’s order in December to overhaul the electricity auction for ...