05000293/FIN-2014008-01
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Finding | |
|---|---|
| Title | Failure to Fully Derive the Causes of a Manual Scram |
| Description | On August 22, 2013, Pilgrim station experienced a failed splice on a nonsafety- related power supply to a level control valve, which caused an electrical transient that directly led to the automatic trip of all three RFPs when combined with a latent issue related to a modification. Entergy performed a RCE of the event and identified the failed splice as a direct cause. Inspectors determined that Entergy failed to investigate the cause of the electrical transient in accordance with station CAP procedures sufficiently to ensure all of the root and contributing causes of the event were understood. Their investigation determined that the splice failed because it was improperly fabricated when it was installed in 1999 as a part of a modification package on balance of plant valves. The splice was inside a flexible conduit, had two splices on parallel wires places right next to each other instead of being staggered, and the splice had not been properly crimped. Entergy performed an extent of condition review to verify there were no other splices installed in flexible conduit by the same modification package. Entergy used multiple causal evaluation methods as part of their RCE. Three of these (event and causal factor charting, failure modes analysis, and the why staircase analysis) discussed the failed splice. Entergys CAP procedures state that neither the failure modes analysis nor the why staircase are acceptable stand-alone methods of evaluation. The failure modes analysis method is described in EN-LI-118-08, Failure Modes Analysis, Revision 2. This procedure states that the output of the failure modes analysis will only be the direct cause, so it must be used with another method. The why staircase method is described in EN-LI-118-11, Why Staircase, Revision 0. This procedure states that for human performance problems, the method may only get to the general area of the cause and most likely will require further analysis to establish the exact cause. In the why staircase for this RCE, Entergy stopped at failure to follow requirements of design change and [procedure] 3.M.3-51, which is a human performance issue. The event and causal factor charting method is described in EN-LI-118-01, Event and Causal Factor Charting, Revision 2, and is the only method of the three intended for stand-alone use. This procedure directs them to continue to investigate and develop the chart until one of the following limits is reached: (1) the cause is outside the control of Entergy, (2) the correction of the cause is determined to be cost prohibitive, (3) the primary effect is fully explained, or (4) there are no other causes that explain the effect being evaluated. Entergy terminated their chart at maintenance work practices, which does not meet any of the criteria listed in EN-LI-118-01. Ultimately, Entergy did not identify corrective actions to correct the cause of the failed splice and inspectors could not verify that actions taken to ensure other splices were not improperly installed were sufficient. The inspectors questioned why Entergy had not continued to investigate what caused the splice to be improperly fabricated in accordance with station procedures such that either appropriate corrective actions could be planned or justification as to why no corrective actions were required could be provided. In response to inspectors questions, Entergy entered the issue into the CAP as CR-PNP-2014-5796 and initiated additional causal analysis to determine why the splice was improperly fabricated. |
| Site: | Pilgrim |
|---|---|
| Report | IR 05000293/2014008 Section 4OA4 |
| Date counted | Dec 31, 2014 (2014Q4) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 95002 |
| Inspectors (proximate) | B Smith C Bickett J Grieves J Patel M Keefe R Mckinley S Morrow S Rich A Keim |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - Pilgrim - IR 05000293/2014008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Pilgrim) @ 2014Q4
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