A roof fall was discvoered at 12:46 AM in an old panel by an examiner. The fall was located in the #5 entry of the 2nd Subpanel No. off of the 4th Panel No. - Old #4 Unit. The fall was located between spads 28+76 & 29+23 (47' L X 18' W X 8.5' H). There were no injuries (or witnesses), or disruptions to ventilation or passage of personnel.