05000443/FIN-2014003-02
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Finding | |
|---|---|
| Title | Unexpected Main Generator Breaker Pole Closure Results in Reactor Trip |
| Description | The inspectors identified a self-revealing finding of very low safety significance (Green), because NextEra did not ensure that adequate procedural guidance existed in ON1046.12, Operation of the Main Generator Breaker to limit the likelihood of events that upset plant stability. Specifically, Seabrook station experienced an automatic reactor trip from approximately 15 percent reactor power on April 1, 2014 when two of four reactor coolant pumps (RCPs) tripped on low bus voltage. The cause of the reactor trip was directly attributable to the main generator breaker inadvertently closing and actuating the main generator multi-function protective relay. NextEra entered the event into their CAP, and conducted a root cause evaluation to determine the root and contributing causes, extent of condition and extent of cause, and to identify corrective actions to prevent recurrence. NextEra initiated actions to revise ON1046.12 to add controls regarding the potential risk associated with placing the main generator breaker control in local, conducted briefings with Maintenance groups involved in the event, and evaluated the adequacy of other Operations procedures that place equipment in a configuration where protective features are bypassed or defeated. The performance deficiency was more than minor because it was associated with the procedure quality attribute of the Initiating Events cornerstone, and it adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. The finding was evaluated under IMC 0609, Attachment 4, Phase 1 Initial Characterization of Findings. The inspectors determined that the finding is of very low safety significance (Green) because it did not result in both a reactor trip and the loss of mitigating equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition. The finding has a cross-cutting aspect in the area of Human Performance - Work Management, because NextEra did not ensure that a process of planning, controlling, and executing work activities such that nuclear safety is the overriding priority was implemented. Specifically, ON1046.12, Operation of the Main Generator Breaker did not contain adequate procedural guidance regarding the impacts of positioning the Main Generator Selector Switch to local, take mitigating actions, and minimize time spent at increased risk configurations [H.5]. |
| Site: | Seabrook  |
|---|---|
| Report | IR 05000443/2014003 Section 4OA3 |
| Date counted | Jun 30, 2014 (2014Q2) |
| Type: | Finding: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | B Dionne C Newport G Dentel P Cataldo T O'Hara |
| CCA | H.5, Work Management |
| INPO aspect | WP.1 |
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Finding - Seabrook - IR 05000443/2014003 | ||||||||||||||||||||||||||||||||||||||
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Finding List (Seabrook) @ 2014Q2
Self-Identified List (Seabrook)
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