Document kKv4vGZGpoa5mK89mVknBy9b

Interoffice Communication To J. E. Barton--- From B. J. Harrison Date February 14, 1977 Subject POWER FAILURE (conoco) On 2/11/77 at 0330, the plant lost power due to a relay failure on the main electrical line to the City of Aberdeen. At the time of the power failure, D-500 was killed and had been on recovery for 30 minutes. D-300 had pressure dropped and was killed waiting recovery. D-400 had been charged for 2 hours and 55 minutes. D-600 had been charged for 55 minutes. When the power went off, the field operators opened the N.O. cylinders and set up the valves to kill D-600 and D-400. They also put nitrogen on the duro seal units and seal water tank. The nitrogen was turned off and on as needed to the air supply. D-600 was killed first with 3 cylinders of N.O. which was enough to stop the reaction. D-400 did not respond to the N.O. Wien I checked, I found the valve to the seal water line still closed. The valve was hidden by insulation on another line. I opened the valve and the N.O. went in. In the meantime, the operators were setting up more N.O. cylinders on D-600, checking the duro seal tanks, and repairing broken flex line on nitrogen line to the seal water tanks. When the N.O. cylinders were empty on D-400, three more were set up and added to the reactor. Put three more full cylinders of N.O. at D-400 and set up to add to the reactor if needed. D-400 responded to the N.O. injection each time it was added but it did not completely kill it. We added three cylinders of N.O. to reactor three times for a total of nine cylinders. It was necessary to manually vent for 5 seconds 2 times while the operators were setting up more N.O. cylinders. Estimated pounds of VCM vented was 300 to 400. No safety discs were blown and no one was exposed to VCM. The power was restored at 0505. c: GGD, ELK, DEM, AIIS dTH 000095874