Sandy likely to shut some U.S. Mid-Atlantic nuclear reactors

* PSEG Salem and Hope Creek reactors likely to shut

* Reactors in Pennsylvania and Maryland could shut

Oct 29 (Reuters) - Hurricane Sandy could shut a few nuclear power reactors in the U.S. Mid-Atlantic before making landfall Monday night. The storm, centered over the Atlantic Ocean about 310 miles (505 km) southeast of New York City, was expected to hit near Delaware and south New Jersey in about 12 hours as a Category 1 hurricane with winds of up to 90 miles per hour (144 kph). The nuclear reactors in Sandy's current path include units at Public Service Enterprise Group Inc's 2,332-megawatt (MW) Salem and 1,161-MW Hope Creek plants, which were likely to bear the brunt of the storm before it moves inland. Sandy was expected to lose some punch as she moves over Pennsylvania and Maryland, crossing near Constellation Nuclear Energy Group's 1,705-MW Calvert Cliffs nuclear plant in Maryland, Exelon Corp's 2,244-MW Peach Bottom, 805-MW Three Mile Island and 2,264-MW Limerick in Pennsylvania, and PPL Corp's 2,450-MW Susquehanna in Pennsylvania. Electricity traders said if Sandy continues on her expected path it was likely PSEG would have to shut the Salem and Hope Creek reactors later Monday, but they were mixed on whether the storm's winds would still be strong enough to force the shutdown of the Pennsylvania and Maryland reactors. All U.S. reactors have procedures that require operators to shut the units before hurricane-force winds reach their sites or when floodwaters reach certain levels. A few reactors in the area were already shut for refueling or other maintenance, including Exelon's Oyster Creek in New Jersey, PSEG's Salem 2 in New Jersey, and PPL's Susquehanna in Pennsylvania. A spokesman at PSEG said only essential personnel were required to report to the Salem and Hope Creek site on Monday. Both Salem Unit 1 and Hope Creek were at full power Monday morning and the refueling work on Salem Unit 2 was suspended by 6 p.m. EDT Sunday, PSEG spokesman Joe Delmar told Reuters.