05000416/FIN-2012003-01
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Finding | |
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| Title | Failure to Ensure Materials are Stored Properly in the 500 KV Switchyard |
| Description | The inspectors identified a finding for the licensees failure to ensure that materials or equipment were not stored under energized lines or near energized equipment in accordance with station procedures. On May 21, 2012, the inspectors were performing a grid stability inspection and toured the 500 KV switchyard with the system switchyard engineer. During the tour, the inspectors identified numerous cylindrical shaped items stored under a 500 KV power line, which posed a missile hazard to the offsite source of power. The licensee determined that the items in question were bushing sleeves that were left in the switchyard following 500 KV breaker maintenance. The inspectors researched station procedures and determined that the cylindrical items stored under the energized 500 KV power line did not meet procedure requirements for the storage of materials and equipment. Immediate corrective actions included having the items removed from the switchyard. The licensee entered this issue into their corrective action program as Condition Report CR-GGNS-2012-07362. The finding is more than minor because it is associated with the protection against external factors attribute of the Mitigation Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The inspectors reviewed Manual Chapter 0609, Attachment A, Phase 1 Initial Screening and Characterization of Findings. Attachment A, Table 4.a, states that a Phase 3 is required if the finding is potentially risk significant due to external initiating event core damage accident sequences. The inspectors determined that the failure to properly store the bushing sleeves in the switchyard could have resulted in a loss of offsite power during a severe weather initiating event. Therefore, the senior reactor analyst evaluated the finding to determine its significance using hand calculations and the site-specific SPAR model. The analyst determined that the probability of having straight-line winds or winds generated by hurricanes or tornados that were strong enough to throw the bushing sleeves into switchyard electrical equipment was between 2.5 x 10-1 and 2.0 x 10-2 /year. The analyst also determined that the conditional probability that bushing sleeves thrown by winds would result in a loss of offsite power was between 1.2 x 10-1 and 1.1 x 10-7. Finally, the SPAR model calculated that the conditional core damage probability for a loss of offsite power initiated in the switchyard was 5.3 x 10-5. Using these values, under all scenarios evaluated by the analyst, the change in core damage frequency caused by the subject performance deficiency was below 1 x 10-6. Therefore, the finding was of very low safety significance (Green). The inspectors determined the finding has a cross-cutting aspect in the area of problem identification and resolution associated with the corrective action program component because the licensee did not implement the corrective action program with a low threshold for identifying materials improperly stored in the 500 KV switchyard. |
| Site: | Grand Gulf  |
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| Report | IR 05000416/2012003 Section 1R01 |
| Date counted | Jun 30, 2012 (2012Q2) |
| Type: | Finding: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.01 |
| Inspectors (proximate) | R Smith A Barrett J Laughlin V Gaddy G Apger A Fairbanks B Rice J Braisted R Kumana |
| CCA | P.1, Identification |
| INPO aspect | PI.1 |
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Finding - Grand Gulf - IR 05000416/2012003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Grand Gulf) @ 2012Q2
Self-Identified List (Grand Gulf)
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