05000389/LER-2012-002, Regarding Non-Segregated Phase Bus Fault Resulting in Partial Loss of Offsite Power

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Regarding Non-Segregated Phase Bus Fault Resulting in Partial Loss of Offsite Power
ML12341A233
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 11/27/2012
From: Jensen J
Florida Power & Light Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2012-403 LER 12-002-00
Download: ML12341A233 (4)


LER-2012-002, Regarding Non-Segregated Phase Bus Fault Resulting in Partial Loss of Offsite Power
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
3892012002R00 - NRC Website

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November 27, 2012 L-2012-403 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Re:

St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 2012-002 Date of Event: October 3, 2012 Non-SreggagtedPhase Bus Fault Resulting n Partial Loss of Offsite Power The attached Licensee Event Report 2012-002 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very truly yours, "St-ucie Plant JJ/rcs Attachment Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

NRC FORM 366 U.S.

NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/3172013

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

St. Lucie Unit 2 05000389 OF 3

4.

TITLE Non-Segregated Phase Bus Fault Resulting in Partial Loss of Offsite Power

5.

EVENT DATE

6.

LER NUMBER }

7.

REPORT DATE

8.

OTHER FACILITIES INVOLVED YEARASEQUENTIA REV 1 MFACILITY NAME DOCKET MOT A ERYEAR IL NUMBER NO.!I MONTH DAY YEAR!

NA NUMBER 10 03 2012 2012 -

002 001 11 27 12 FACILITY NAME DOCKET NUMBER

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)

N/A El 20.2201(b)

El 20.2203(a)(3)(i)

[I 50.73(a)(2)(i)(C)

[E 50.73(a)(2)(vii)

El 20.2201(d)

El 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

El 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B)

F] 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL El 20.2203(a)(2)(ii)

El 50.36(c)(1)(ii)(A)

[

50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

El 20.2203(a)(2)(iii)

El 50,36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4) 0%

[1 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

[I 50.73(a)(2)(v)(B)

[1 73.71(a)(5)

El 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

El 50.73(a)(2)(v)(C)

El OTHER El 20.2203(a)(2)(vi)

El 50.73(a)(2)(i)(B)

El 50.73(a)(2)(v)(D)

Specify in Abstract below or in Due to the common high side electrical feed, the 2B Startup Transformer lockout resulted in the concurrent loss of the lB Startup Transformer.

Unit 1 was operating in Mode 1, with the normal electrical alignments to the Auxiliary Transformers, and the 1A EDG out of service for maintenance.

There was no immediate impact on Unit 1.

However, Unit 1 entered Technical Specification action statement 3.8.1.1.c due to the loss of one offsite A.C. circuit and one diesel generator being out of service for maintenance.

The lB Startup Transformer was returned to service within the specified time period and Technical Specification 3.8.1.1.c was exited.

Prompt Corrective Action Immediate corrective actions included repairs to the degraded vents on the affected non-segregated phase bus run.

Corrective Actions

The corrective action below has been entered into the site corrective action program.

Any changes to the action will be managed under the corrective action program.

1. Update the preventive maintenance bases for startup and auxiliary transformers to improve periodic maintenance of non-segregated phase bus run vent assemblies.

Similar Events

A search of the corrective action database for three years was performed and identified no issues that were related to the faults identified with this event.

Failed Component(s) 2B Startup Transformer 6.9kV non-segregated phase bus [NSBU:EA] vent assembly.

Manufacture:

Cutler Hammer Model:

Medium Voltage Nonsegregated Phase Bus Run