ENERGY POINT

August 23,2012

BEACH

NRC 2012-0061 10 CFR 50.73

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27

Licensee Event Re~or t 2661201 2-003-00 2B-04 Safenuards 480V Bus De-Energized

Enclosed is Licensee Event Report (LER) 26612012-003-00 for Point Beach Nuclear Plant, Units 1 and 2. NextEra Energy Point Beach, LLC is providing this LER regarding 26-04 safeguards 480V bus feeder breaker trip.

This submittal contains no new or revised regulatory commitments.

If you have questions or require additional information, please contact Mr. Jim Costedio at 9201755-7427.

Very truly yours,

NextEra Energy Point Beach, LLC

Enclosure

cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW

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NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

~ ~ N R C FORM 366 U.S. NUCLEAR REGULATORY COMMISSION 1 APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (1

LICENSEE EVENT REPORT (LER)

I Estimated burden per response to comply with this mandatory collection request: 80 hours. Reported lessons learned are incorporated into the 11 licensing process and -fed back to industry. Send cominents regarding burden estimate to the FOINPrivacy Section (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e- mail to infocollects.resourse@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC mav not conduct or sDonsor, and a person is not

Point Beach Nuclear Plant I 05000266 I 1 of 3 4. TITLE

1 required to respond to, the information collection.

111. FACILITY NAME 12. DOCKET NUMBER 13. PAGE

(12~-04 Safeguards 480V Bus De-Energized 11

I

50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50,73(a)(2)(viii)(B)

[7 50.73(a)(2)(ix)(A) I7 50.73(a)(2)(x)

73.71(a)(4) 73.71(a)(5) OTHER Specify in Abstract below or in NRC Form 366A

5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED

12. LICENSEE CONTACT FOR THlS LER NAMF TELEPHONE NUMBER (Include Area Code)

FACILITY NAME MONTH DAY YEAR YEAR

REV MONTH NUMBER NO. DAY YEAR Point Beach Nuclear Plant

06 06 2011 2012 - 003 - 00 08 28 2012

DOCKET NUMBER

05000301

ABSTRACT (Limit to 1400 spaces, Le., approximately 15 single-spaced typewritten lines)

On June 6,201 1, while Unit 1 was in MODE 1 and Unit 2 was in MODE 4, the feeder breaker to safeguards 480V bus, 2B-04, opened on overcurrent.

9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFRS: (Check all that apply)

. . . .. . . -

Kim Locke - Engineering Analyst 19201755-7464 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT

The feeder breaker tripped on overload after energizing a pressurizer heater group. This trip resulted in de- energizing electrical bus 2B-04. No other breakers tripped during this event. The results of an investigation determined the overload trip was improperly set low.

MANU- CAUSE SYSTEM COMPONENT CAUSE SYSTEM COMPONENT FACTURER

REPORTABLE TO EPIX

NA NA NA N A NA NA NA NA

14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED SUBMISSION

YES (If yes, complete 15. EXPECTED SUBMISSION DATE) E l NO DATE

A technical assessment for reportability was completed. Nextera Energy Point Beach, LLC (NextEra) determined that electrical bus 2B-04 was inoperable for specific time periods from March 23, 201 1 through June 7, 2011 for Unit 1 and Unit 2. Technical Specification Limiting Conditions for Operation (LCOs) and associated Action Conditions (TSACs) for TS 3.8.9 Distribution System - Operating (TSAC 3.8.9 A and B), TS 3.8.10 Distribution Systems - Shutdown (TSAC 3.8.10 A), and TS 3.5.3 ECCS - Shutdown (TSAC 3.5.3 A and B) were not met during specific time periods. Therefore, pursuant to 10 CFR 50.73(a)(2)(i)(B), the event is reportable as a condition prohibited by Technical Specifications. This event is also being reported pursuant to 10 CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.

The feeder breaker overload trip setting was corrected.

FEt!kR NA

NCR FORM 366 (10-2010)

REPORTABLE TO EPlX

NA

MONTH DAY YEAR

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1 0-201 0)

LICENSEE EVENT REPORT LER) CONTINUATION SHEE

1. FACILITY NAME

4 r o 3. PAGE

Point Beach Nuclear Plant 05000266 Page 2 of 3

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Description of the Event

On June 6,201 1, while Unit 1 was in MODE 1 at 100% power and Unit 2 was in MODE 4, the feeder breaker [EB] to safeguards 480V bus, 2B-04, opened on overcurrent.

The feeder breaker tripped on overload after energizing a pressurizer heater group. This trip resulted in de-energizing electrical bus 2B-04. No other breakers tripped during this event. The results of an investigation determined the overload trip was set low.

As part of the casual analysis it was determined that a spare feeder breaker was setup with an overload setting not appropriate for use as the feeder breaker for bus 2B-04. As part of a PM activity, the spare breaker was staged for swapping into the feeder breaker cubicle for bus 2B-04 and subsequently installed. The breaker was not loaded above the overload setting until the Unit 2 heat-up in MODE 4 when a pressurizer heater group was energized and the overload trip occurred. After the breaker trip, the feeder breaker was replaced with a spare breaker that had satisfactorily completed breaker maintenance and had a correctly set overload.

A technical assessment for reportability was completed. NextEra determined that bus 2B-04 was inoperable for specific time periods from March 23, 201 1 through June 7, 201 1 for Unit 1 and Unit 2. Technical Specification LCOs and associated TSACs for TS 3.8.9 Distribution System - Operating (TSAC 3.8.9 A and B), TS 3.8.10 Distribution Systems - Shutdown (TSAC 3.8.10 A), and TS 3.5.3 ECCS - Shutdown (TSAC 3.5.3 A and B) were not met during specific time periods. Therefore, pursuant to 10 CFR 50.73(a)(2)(i)(B), the event is reportable as a condition prohibited by Technical Specifications.

The improperly set bus 2B-04 supply breaker, in conjunction with a postulated MODE 4 LOCA, may have caused a simultaneous loss of low head injection and containment sump recirculation capability. This resulted in TS 3.5.3 ECCS - Shutdown (TSAC 3.5.3 A and B) not being met for Unit 2. Therefore, pursuant to 10 CFR 50.73(a)(2)(v)(D) this event is being reported as a safety system functional failure for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.

Cause of the Event

The cause of the event was the breaker's incorrect overload trip setting.

Analysis of the Event

The 480V system buses and switchgear are supplied by the 4.1 6 kV system through the 41 601480 VAC station service transformers (X-I I through X-14) and diesel generator building transformers (X-06). The 480 volt safeguards equipment is connected to buses B-03 and B-04. Power for safeguards valve motors is supplied from the motor control centers B-32 and B-42 which in turn are served from buses B-03 and B-04, respectively. Since the normal source of power for these buses is the 345 kV system (via station auxiliary transformers X-03 and X-04; 41 60 volt buses A-03, A-05 and A-04, A-06; and station service transformers X-13 and X-14).

Under certain plant configurations of operating equipment, the lower amperage setting may have caused the feeder breaker to trip thus removing power from bus 2B-04 and making it incapable of performing its safety function. An engineering evaluation was performed to determine the time periods when bus 2B-04 may not

NRC FORM 366A (10-2010)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (10-2010)

LICENSEE EVENT REPORT LER) CONTINUATION SHEE

1. FACILITY NAME

i P O 3. PAGE

Point Beach Nuclear Plant 05000266 Page 3 of 3

- - - - NARRATIVE

have been capable of performing its safety function. For the periods of time that the feeder breaker with the improper setting was installed in bus 2B-04, the operating conditions were Unit 1 in MODE 1 and Unit 2 in MODE 4, 5, 6, or Defueled.

The feeder breaker was placed in service with the improper setting on March 23, 201 1. A breaker with the correct setting was installed on June 7, 201 1. Between those dates NextEra determined that bus 2B-04 was inoperable for specific time periods. Technical Specification Limiting Conditions for Operation (LCOs) and associated Action Conditions (TSACs) for TS 3.8.9 Distribution System - Operating (TSAC 3.8.9 A and B), TS 3.8.10 Distribution Systems - Shutdown (TSAC 3.8.10 A), andlor TS 3.5.3 ECCS - Shutdown (TSAC 3.5.3 A and B) were not met during specific time periods.

Analysis of Safety Significance

During the time periods when bus 2B-04 may have been incapable of supplying its required loads for Unit 1, the operating loads and those loads expected to be started in response to a Unit 1 event, could have caused the incorrectly set feeder breaker to bus 2B-04 to trip open. The loss of bus 2B-04 may have an impact on Unit 1 risk due to the commonlshared loads normally powered by bus 2B-04, such as K-3B Service Air Compressor, P-32D and P-32E Service Water Pumps, P-38B Standby Steam Generator Feedwater Pump, K-2B Instrument Air Compressor, and the 0-08 Battery Charger. NextEra determined the event to be of very low safety significance for Unit 1. A review for Safety System Function Failures (SSFFs) for Unit 1 determined that there was no SSFF because redundant equipment remained in service during the event.

Unit 2 was in Modes 4, 5, 6, or defueled during this time period. A deterministic, defense-in-depth, shutdown safety assessment process was used to evaluate the significance of this issue. Time periods when bus 2B- 04 was determined to be inoperable was used in the assessment. Based on the assessment, the issue was considered to be of very low safety significance for Unit 2. A review for SSFFs for Unit 2 determined that there was a SSFF because the improperly set bus 2B-04 supply breaker, in conjunction with a postulated MODE 4 LOCA, may have caused a simultaneous loss of low head injection and containment sump recirculation capability.

Corrective Actions

A feeder breaker with the proper overload setting was installed in electrical bus 2B-04.

A root cause evaluation was completed and corrective actions were developed to address organizational and programmatic issues.

Similar Events

None

Failed Components

None

NRC FORM 366A (10-2010)