EMPLOYEE SAID THE ONLY INCIDENT THAT HE COULD TIE THE INJURY TO WAS WHEN HE WAS ROOF BOLTING ON THE LEFT SIDE OF THE BOLTER ON UNIT #3 IN THE FACE OF NUMBER 1 ENTRY. AS HE WAS COUPLING A DR ILL STEEL DOWN INTO A BOLTER WRENCH. DRILL STEELPOPPED INTO THE PALM OF HIS LEFT HAND. LATER DISCOVERED HE HAD A BROKEN BONE IN THE KNUCKLE AREA.