The Nuclear Regulatory Commission has agreed to transfer plant licenses associated with the proposed merger of Exelon and Constellation Energy. The orders from the NRC, announced by the companies Thursday, are among that last regulatory approvals they need to close the deal.Constellation owns just over half of Constellation Energy Nuclear Group, with EDF holding the minority stake. CENG operates reactors at the Calvert Cliffs, Nine Mile Point and R.E. Ginna plants in Maryland and New York. And federal regulations require NRC action on their licenses because of CENG’s proposed “upstream” change of ownership.“We are pleased that the NRC has approved the license transfer, which is a key step toward completing our merger,” Exelon President Christopher M. Crane said in a release. “The merger with Constellation is a major objective of Exelon’s growth strategy, and the NRC approval is an important milestone in the process.”With 17 units, Exelon already owns the largest power reactor fleet in the country. CENG will retain ownership of its five reactors, with Exelon acquiring indirect control of Constellation’s stake. Earlier, EDF had petitioned Maryland regulators to block the merger, arguing it would threaten CENG’s autonomy and create a company whose size would make it harder to pass regulatory scrutiny when seeking to build new plants. The French company dropped its opposition last month after negotiations with the merging firms.