05000313/FIN-2010003-07
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Finding | |
|---|---|
| Title | Failure to Consider Failure Modes Results in Main Feedwater Pump Over Speed Trip |
| Description | The inspectors documented a self-revealing finding for the failure of the licensee to perform a thorough design change evaluation which did not recognize and address all design failure modes. Specifically, the licensee failed to address the water intrusion into the electronic modules of the main feedwater pump control system from a possible failure of the condensate drain system of the control cabinet air conditioning units. On May 1, 2010, water emanating from the air conditioning units above the Lovejoy control cabinets, dripped into the electronic modules and caused oscillations in main feedwater pump A speed before tripping on an actual overspeed condition. Unit 1 automatically ran back from 100 percent power to 40 percent power as designed. The licensee entered this issue into the corrective action program as Condition Report CR-ANO-1-2010-2150.
Failure to adequately consider the potential failure modes of the air conditioning cooling to the local Lovejoy control cabinets for the main feedwater pumps was a performance deficiency. Specifically, the licensee did not consider the condensate drain pan and piping failure that could, and in this case did, introduce water into the control cabinet electronics and did not implement actions to monitor or initiate preventative measures to preclude this from occurring. The performance deficiency was determined to be more than minor because it is associated with the design control attribute and directly affected the Initiating Events Cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during power operations, and is therefore a finding. The inspectors evaluated the significance of the finding using Manual Chapter 0609, Significance Determination Process, Phase 1 Worksheets, and determined the finding to be of very low safety significance because the finding did not contribute to both the likelihood of a reactor trip and the likelihood that mitigation equipment or functions would not be available. The inspectors determined that there was no crosscutting aspects associated with this finding because the performance deficiency is not indicative of current plant performance and is a latent issue as the modification was installed in 1996. |
| Site: | Arkansas Nuclear  |
|---|---|
| Report | IR 05000313/2010003 Section 4OA3 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | J Josey J Rotton N Greene A Sanchez D Stearns E Uribe G George J Clark |
| INPO aspect | |
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Finding - Arkansas Nuclear - IR 05000313/2010003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Arkansas Nuclear) @ 2010Q2
Self-Identified List (Arkansas Nuclear)
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