UPDATE 1-Top E.Coast refiner seen unharmed by Sandy as checks begin
By: Janet McGurty
*Philadelphia 330,000 bpd refinery, biggest on coast, undamaged-source. NEW YORK, Oct 30- The biggest U.S. East Coast refinery in Philadelphia appears to have emerged undamaged from Hurricane Sandy and a smaller nearby plant operated without trouble, sources said on Tuesday as energy firms began assessing the storm's damage.