05000219/LER-2012-002-01, Regarding Loss of Offsite Power During Hurricane Sandy
| ML13190A465 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/26/2013 |
| From: | Peak R Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 12-002-01 | |
| Download: ML13190A465 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2192012002R01 - NRC Website | |
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- 3. PAGE Oyster Creek, Unit 1 05000219 1 OF 3
- 4. TITLE Loss of Offsite Power During Hurricane Sandy
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED RFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SUE REV MONTH DAY YEAR N/A N/A M O T_
FACILITY NAME DOCKET NUMBER 10 29 2012 2012 002 01 06 20 2013 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[I 50.73(a)(2)(vii)
N [0 20.2201(d)
[I 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
[0 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
[I 20.2203(a)(4) 0 50.73(a)(2)(ii)(B)
[I 50.73(a)(2)(viii)(B)
[I 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
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50.73(a)(2)(iv)(A)
[I 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
[I 50.36(c)(2)
El 50.73(a)(2)(v)(A)
[] 73.71(a)(4) o[ 20.2203(a)(2)(iv)
[I 50.46(a)(3)(ii)
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El 73.71(a)(5) 0 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
[I OTHER [o 20.2203(a)(2)(vi)
[I 50.73(a)(2)(i)(B)
[E 50.73(a)(2)(v)(D)
Specify in Abstract below or in the EDGs. Emergency Plan (EP) Emergency Action Levels (EALs) were reviewed by the Shift Manager and found to be not applicable in the Cold Shutdown mode of operation since both EDGs started and loaded as required.
At 10:39 on October 30, 2012, power was restored to Startup Transformer Bank 5 and EDG #1 was secured.
Due to equipment damage to the Bank 6 Voltage Regulator, Startup Transformer Bank 6 was not returned to service at that time. At 3:46 on October 31, 2012, a planned contingency offsite power backfeed path was established to repower plant loads associated with EDG#2 and EDG #2 was secured. At 21:32 on November 1, 2012, with the Bank 6 Voltage Regulator repair complete and power restored to Startup Transformer Bank 6, the planned contingency offsite power backfeed was secured.
Analysis of Event
This event was of low significance since Oyster Creek was in Cold Shutdown with reactor water level at 585 inches above the fuel, and both EDGs fast started as designed repowering all required emergency loads.
Prior to the arrival of Hurricane Sandy, Oyster Creek ensured that both EDGs and the associated safety system electrical buses were available and operable. Oyster Creek also ensured that an adequate amount of fuel oil was available for sustained EDG operation. The Operations Department was prepared and briefed for the oncoming storm. The Operators were prepared for and briefed for the LOOP, loss of Shutdown Cooling, as well as the loss of Fuel Pool Cooling. The Operators took appropriate actions and expeditiously recovered Shutdown Cooling and Fuel Pool Cooling following the initial EDG loading sequence. There were no significant equipment problems noted related to maintaining the reactor in a safe Cold Shutdown Condition during the LOOP. There were no safety consequences impacting the plant or public safety as a result of this event.
Cause of Event
A detailed root cause investigation was performed and found that the wall falling onto the 'C' phase of the Bank 6 Voltage Regulator was the root cause of the event. When the wall fell onto the 'C' phase of the Bank 6 Voltage Regulator a ground fault condition occurred, and due to the Bank 6 OCB failing to clear the fault, resulted in isolation of the local 34.5KV system, resulting in the Oyster Creek LOOP. The wall was installed as part of a modification, performed in the mid 1980s, and was not built to withstand the winds experienced during the storm.
Oyster Creek license conditions require that switchyard equipment be inspected under the 'Structures Monitoring Program' every 4 years. The wall has been regularly inspected without detection of any structural deficiencies-with the last inspection being performed in September 2012. No deficiencies with the wall were documented.
Contributing to the LOOP was the stuck breaker condition on the Bank 6 OCB, which failed to clear the fault as designed. Corrective maintenance on Bank 6 OCB after the event discovered that the trip coil had failed which would have prevented the breaker from opening. With the Bank 6 OCB stuck, the fault was propagated throughout the local 34.5KV system resulting in the LOOP.
Corrective Actions
Prior to reactor startup from the Refueling Outage, Oyster Creek verified that all required electrical distribution power lines and equipment required by Technical Specifications were available, operable, and functioning as required. This verification included ensuring that the transmission owner/operator completed the replacement and testing of the failed trip coil and the Bank 6 OCB.
In order to prevent recurrence it was verified that the defective wall was not part of Oyster Creek's current license or design basis and the wall was removed. Additionally, the transmission system owner/operator has performed a modification in the Oyster Creek switchyard to provide stuck breaker protection for the 34.5KV breakers.