05000335/LER-2012-006
| Docketsequentia Revmonth Day Year Year Month Day Year Na Numberl Number No. | |
| Event date: | 06-05-2012 |
|---|---|
| Report date: | 08-02-2012 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3352012006R00 - NRC Website | |
Description of the Event
On June 5, 2012 at 1314 EDT, St. Lucie Unit 1 was in Mode 1 at 100% reactor power and performing monthly flow testing of lA auxiliary feed pump when the lA auxiliary feed pump flow transmitter, FT-09-2A, was discovered to be inoperable. Upon troubleshooting, it was discovered that the leads were wired incorrectly on the square root extractor, and the indication was non-functional. The square root extractor had been replaced with a different design on May 9, 2012, and declared operable on May 10, 2012, while the flow transmitter was actually inoperable. This condition unknowingly existed for greater than the allowable Technical Specification action time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per Technical Specification 3.3.3.8.
Cause
A root cause evaluation determined that vague procedure guidance for post maintenance testing, inadequate vendor technical drawings and a previous event not captured in the corrective action program were causes and contributors to entering a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specification action statement greater than the allowable time.
Analysis of the Event
The root cause for returning the flow transmitter in an inoperable condition following maintenance was a failure to identify and correct the wiring error due to an incomplete procedure for the required post-maintenance testing (PMT).
Additional contributing causes led to the wiring error. The new square root extractor had a less than adequate item equivalency evaluation (IEE) that did not address potential wiring issues during installation, and work order instructions lacked the information needed to ensure the. square root extractor would be installed correctly. The vendor technical manual for the new square root extractor provided a drawing with a call-out box that identified the terminals that needed to be wired to ensure the square root extractor performed its designed function. However, there was nothing in the work order or the drawing that directed personnel to utilize the information in the call-out box located at the bottom of the drawing.
Safety Significance
This event had no significant safety consequence since an auxiliary feedwater actuation had not occurred while the flow transmitter leads were wired incorrectly.
The auxiliary feedwater puthp flow transmitter, FT-09-2A, which provides flow indication function, is not considered in the PRA model because its inoperability will not impact the respective auxiliary feedwater pump from performing its design function under accident conditions. Therefore, there is no risk impact associated with the reported inoperability of FT-09-2A.
This licensee event report is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition which was prohibited by the plant's Technical Specifications.
Corrective Actions
The corrective actions listed below are entered into the site corrective action program. Any changes to the actions will be managed under the corrective action program.
1. The wiring was corrected and tested to return the flow transmitter to operable status on June 5, 2012 at 2100 EDT.
2. The Station will revise the post-maintenance test procedure to strengthen the guidance for the requirements and instructions for performing channel functional testing.
3. The Station will revise the vendor tech manual drawing for installation of these square root extractors to ensure end users refer to Detail A for guidance on landing leads to the correct terminals.
Similar Events A similar event was identified and corrected in March 2009 when PMT and subsequent troubleshooting identified that a newly installed square root extractor was wired incorrectly. � However, this information was not captured in a condition report or as internal operating experience.
Failed Component(s) Rochester Instrument Systems model SC-1330 square root extractor Manufacturer Rochester Instrument Systems