AT 3:34 PM ON AUGUST 25 A UTILITY POWER INTERUPTION CAUSED THE COAL MILL TO SHUT DOWN. AT 3:45 PM THE MILL WAS RESTARTED. AT 4:03 PM THE PRESSURE RELIEF VALVE BLEW OFF THE MILL DAMAGING TWO THERMOCOUPLES. VALVE AND THE THERMOCOUPLES WERE REPLACED AND THE MILL INSPECTED AND RESTARTED WITHOUT INCIDENT.