On October 8, 2016, during the performance of preventive maintenance of the transformer winding turns ratio test on the 480V Shutdown Board transformer TS1 B, it was discovered that the transformer was set on the incorrect tap. This would result in lower than minimum required voltages at the electrically downstream buses and equipment during a postulated loss of coolant accident coincident with degraded voltage conditions. Transformers TS1A and TS1 Band their associated 480V shutdown boards were determined to be inoperable since installation prior to Unit 1 restart from an extended outage in 2007. This event is being reported as a condition which was prohibited by the plant's Technical Specifications, a condition that could have prevented the fulfillment of the safety function of structures or systems thatare needed to shut down the reactor and maintain it in a safe shutdown condition, remove residual heat, or mitigate the consequences of an accident, and a condition that resulted in the nuclear plant being in an unanalyzed condition that significantly degrades plant safety.
The cause of this event was the technicians did not use the correct drawings to install the transformers because they were incorrectly classified and listed as "documentation only" drawings. There were no steps in the work order to correctly set the taps. Corrective actions were to re-set the taps for the transformers in accordance with the applicable drawing, validate other similar transformer settings, and revise the classification for the applicable drawing.
Monday, May 08, 2017
Junk Facility Browns Ferry: TVA Doesn't Use Procedures
There are two procedures problems here, one address and one not.
The techs should have had a procedure for this. They setting up lower level employees to failure without having procedures. The "corrective action" procedure wasn't followed in that no procedures set this event up?