05000458/LER-2004-001
| Docket Numbers Eausiaal Remo Day Year Year No Mo Day Year 05000 | |
| Event date: | 08-15-2004 |
|---|---|
| Report date: | 10-14-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(a) |
| LER closed by | |
| IR 05000458/2005005 (13 February 2006) | |
| 4582004001R00 - NRC Website | |
slowly in response to the offsite electrical faults. This ultimately resulted in actuation of the main transformer protective relaying scheme, causing the main turbine trip and reactor scram.
Additionally, circuit breaker speed time testing provided inaccurate data due to a testing methodology that inadvertently pre-conditioned the breakers just prior to testing, thereby biasing the test results. The test methodology utilized test equipment that required the breaker to be open and isolated for connection. It was determined that the predictive maintenance (PM) instructions for the 230kv breakers are general in nature and rely on vendor manuals to supply the necessary details. However, the vendor manuals are not written to a level of detail that gives the maintenance technician specific instructions on which parts to lubricate and how often lubrication is needed. The instructions are not sufficient to ensure correct and repeatable maintenance of the breakers. As such, Transmission department maintenance personnel depend heavily on experience and "skill of the craft" to perform the task.
The last major PM of the breakers was performed in 1989. During this maintenance, lubrication was performed on an as-needed basis. This maintenance did not involve cleaning of the old lubricant but rather addition of an aerosol spray. This method of lubrication, while providing short term improvement in breaker trip time performance, actually resulted in degradation of the grease in the mechanism.