Dominion resources Inc. and exelon Corp. are apparently at the head of the line for construction of the first new commercial nuclear reactors in a quarter century. Amid spreading concerns about power reliability and air quality, the nuclear industry is sensing an opportunity to get back into the electricity-generation game, and the two utilities increasingly are being seen as potential leaders of the renascent movement.

A staff member at the Nuclear Regulatory Commission has reported that Richmond, Va.-based Dominion is considering building a new unit at its 1,960-Mw North Anna plant where two of four planned nuclear units were completed in the 1970s, says David Lochbaum, nuclear safety engineer with the Union of Concerned Scientists, Washington, D.C. According to published reports, Chicago-based Exelon also is believed to be seriously considering site permitting for a new unit at its 985-Mw Clinton nuclear station in Illinois. Exelon, established by the merger of Unicom Corp. and PECO Energy Co., is an investor in the pebble-bed modular reactor under development by Eskom, the South African utility. Exelon has selected a smaller next- generation reactor as its strategy. Exelon will meet this month with NRC for preapplication discussions, says Victor Dricks, NRC spokesman.

Formal applications have not been made so far, says Dricks. And Rick Zuercher, Dominion spokesman, says, "We have no plan to build a new nuclear powerplant." Mary Rucci, Exelon spokeswoman, says, "We are still in the process of assessing the technology and the economics. Until we have had an opportunity to thoroughly review those, we would not be making an application."