05000275/FIN-2013005-03
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Finding | |
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| Title | Auxiliary Feedwater Actuation Due to a Main Feedwater Pump Trip |
| Description | The inspectors reviewed a Green self-revealing finding due to an inadequat
procedure for calibrating non-vital bus relays. This caused an initiating event due to a main feed pump trip and unplanned downpower transient to 50 percent power on Unit 1 The licensees failure to maintain an adequate maintenance procedure for calibrating nonvital bus relays is a performance deficiency. Specifically, the procedure was inadequate in that it contained an optional step to position a cut-out switch so that the relay would not deenergize the bus if actuated during maintenance activities. The performance deficiency was more than minor because, if left uncorrected, the performance deficiency had the potential to lead to a more significant safety concern. In particular, when the bus de-energized and tripped the running control oil pump, and the accumulator was unable to maintain system pressure while the back-up control oil pump reached operating pressure, the main feed pump tripped which resulted in a reactor power transient greater than 20 percent. Using Inspection Manual Chapter 0609, Attachment 04, Initial Characterization of Findings, and Appendix A, Exhibit 1, Initiating Events Screening Questions, this finding was determined to be of very low safety significance (Green) because, although it resulted in a reactor transient, it did not result in the loss of mitigating equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition. This finding was entered into the corrective action program as Notification 50588799. This finding had a cross-cutting aspect in the area of human performance, associated with the work control component, because the licensee did not adequately plan and coordinate maintenance activities. Specifically, the licensee did not appropriately assess the job site conditions that could impact human performance and human-system interface by failing to incorporate operating experience into procedural guidance H.3(a). |
| Site: | Diablo Canyon  |
|---|---|
| Report | IR 05000275/2013005 Section 4OA3 |
| Date counted | Dec 31, 2013 (2013Q4) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | A Alen B Parks C Smith G Guerra J Laughlin R Kumana T Hipschman W Walkerb Parks C Smith G Guerra J Laughlin R Kumana T Hipschman W Walke |
| CCA | H.5, Work Management |
| INPO aspect | WP.1 |
| ' | |
Finding - Diablo Canyon - IR 05000275/2013005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Diablo Canyon) @ 2013Q4
Self-Identified List (Diablo Canyon)
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