05000301/LER-2011-003, Regarding Condition Prohibited by Technical Specification 3.8.2, AC Sources-Shutdown
| ML111590186 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/07/2011 |
| From: | Meyer L Nextera Energy |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NRC 2011-0056 LER 11-003-00 | |
| Download: ML111590186 (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 |
| 3012011003R00 - NRC Website | |
text
June 7,201 1 ENERGY POINT BEACH NRC 201 1-0056 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 2 Docket 50-301 Renewed License No. DPR-27 Licensee Event Re~ort 30112011-003-00 Condition Prohibited bv Technical S~ecification 3.8.2, AC Sources - Shutdown Enclosed is Licensee Event Report (LER) 30112011-003-00 for Point Beach Nuclear Plant (PBNP), Unit 2. This LER documents entry into a condition in which standby emergency power to buses 2B-03, and 28-04 were inoperable for a period of approximately four (4) hours.
Pursuant to 10 CFR 5OS73(a)(2)(i)(B), the event is reportable as a condition prohibited by TS.
This submittal contains no new or revised regulatory commitments.
If you have questions or require additional information, please contact Mr. James Costedio at 9201755-7427.
Very truly yours, NextEra Energy Point Beach, LLC Larry Meyer Site Vice President Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
INRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSIoN
,~.JtlY 1U4 10-2010)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons leamed are incorporated Into the licensing process and fed back to Industry. Send comments regarding LICENSEE EVENT REPORT (LER) burden estimate to the FOIAlPrivacy Section (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Intemet 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 may not conduct or sponsor, and a person Is not required to respond to, the Information collection.
1r*
PAGE Point Beach Nuclear Plant, Unit 2 05000301 1 of 3
- 4. TITLE Condition Prohibited by Technical Specification 3.8.2, AC Sources-Shutdown
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR PBNP, Unit 1 05000266 FACILITY NAME DOCKET NUMBER 04 08 2011 2011 -
003 - 00 06 07 2011 N/A N/A
- 19. OPERATING MODE
- 11. THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
Unit 1: MODE 1 D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
Unit 2: MODE 5 D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
D 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(0)(1 )(ii)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(0)(2)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
Unit 1: 100%
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5)
Unit 2: 0%
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(C)
D OTHER D 20.2203(a)(2)(vi) 181 50.73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER NAME I
TELEPHONE NUMBER (Include Area Code)
Fritzie Flenlje, Licensing Supervisor 920/755-7656 CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION
- - D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 181 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 7, 2011, power to the Unit 2 Train A safeguards rack was removed from service under a clearance order. The clearance order did not identify that the removal of power affected the service water (SW) pump automatic-start on breaker closure for the 2A-05 safeguards bus. SW pump auto-start is required for standby emergency power operability on the associated Train A safeguards bus. The absence of the auto-start feature for the affected SW pumps rendered G-02, Train A emergency diesel generator (EDG), inoperable. On April 8, 2011, Train B EDG G-04 was removed from service for monthly surveillance testing. This action resulted in standby emergency power to the 2B-03 and 2B-04 safeguards buses being inoperable for a period of approximately four hours. This exceeded the Completion Time for Technical Specification (TS) 3.8.2, Condition B, Required Action B.1 of Immediately. It was not identified that there was an issue until near the end of a G-04 surveillance test, when operators were unable to initiate a containment isolation (CI) signal during the performance of a refueling test. By the time the reason for this condition had been determined, EDG G-04 testing had been completed and the EDG returned to service and declared operable.
The event was caused by human performance errors that occurred in the development and approval of the clearance order. Corrective actions are being tracked to completion in the corrective action program.
Pursuant to 10 CFR 50.73(a)(2)(i)(B), the event is reportable as a condition prohibited by Technical Specifications.
NRC FORM 366 (10-2010)
Point Beach Nuclear Plant, Unit 1
Event Description
During the ongoing Unit 2 Refueling 31 outage, with Unit 2 in MODE 5 and Unit I in MODE I (100% power),
clearance orders were developed to support termination of wiring for the Unit 2 Train A and Train B safeguards buses. The clearance orders opened the primary input DC breaker to its respective Unit 2 Train A and Train B safeguards relay circuitry. The clearance orders were hung on April 6 and 7, 201 I.
On April 8,201 1 at 20:31 CST, Train B emergency diesel generator (EDG) G-04 [EK], was removed from service for its monthly Technical Specification (TS) test. Preparations for the Unit 2 containment integrated leak rate test were being performed concurrently with the G-04 monthly surveillance. One of the required actions was to manually test the Unit 2 containment isolation (CI) function [JM]. At 23:36 CST, operators were unable to initiate a CI signal. While investigation of this issue was in progress, the G-04 surveillance test was completed on April 9, 201 1, at 00:36 CST and the EDG was returned to service.
Removal of the G-04 EDG from service for surveillance testing at 20:31 CST resulted in an unplanned and unidentified TSAC entry into TS 3.8.1.G for Unit 1 and TS 3.8.2.B for Unit 2 that rendered standby emergency power to 41 60 V buses 2A-05 and 2A-06 and 480 V buses 2B-03 and 2B-04 inoperable for approximately four (4) hours. The Completion Time for TS 3.8.2.B is Immediately. Accordingly, this resulted in a condition prohibited by Technical Specifications and is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B).
The Completion Time for TS 3.8.1.G is two (2) hours, with subsequent Condition H requiring that the affected unit be in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. EDG G-04 was returned to service approximately two hours into the Condition H specification.
The event does not constitute a safety system functional failure.
Analysis of the Event
The clearance orders included opening of the primary DC input breaker and removing actuation power to the A or B train-specific safeguards relay rack. One of the clearance orders removed power to the Train A service water (SW) pump auto-start relay associated with the G-02 EDG, while the second removed power to the Train B SW pump auto-start relays. Technical information used to develop the clearance orders superficially appeared to be similar for both the A and B trains. However, the A Train G-01 and G-02 EDG associated SW pump auto-start feature information provided in the Bases for TS 3.8.1 was not clearly delineated in the technical information used to develop the clearance orders.
The Bases for TS 3.8.1 state the Train A SW pump auto-start feature is required for operability of the unit's 4160 V standby emergency power sources (IA-05 or 2A-05). The A train EDGs (G-01 and G-02) are dependent upon SW for cooling, while the B train EDGs (G-03 and G-04) are not. Therefore, the auto-start signals are not required to support operability of the IA-06 or 2A-06 4160 V standby emergency sources supplied by G-03 and G-04. The clearance order did not affect the SW pump auto-start feature for EDG G-01.
Therefore, EDG G-01 was operable during this event.
With EDG G-04 out of service for surveillance testing and G-02 EDG out of service due to the SW auto-start signal being defeated, standby emergency power was not available for 4160 V buses 2A-05 and 2A-06.
These buses feed 480 V buses 2B-03 and 2-B-04, respectively. Therefore, the loss of standby emergency power to 480 V buses 2B-03 and 2B-04 for approximately four (4) hours should have resulted in an entry into Point Beach Nuclear Plant, Unit 1 TS 3.8.2.B for Unit 2 with a Required Action B.1 Completion Time of Immediately. As previously noted, standby emergency power to buses 2B-03 and 2B-04 was restored when EDG G-04 was returned to service following completion of a successful surveillance test, and prior to a determination of the cause of this event.
Cause of the Event
The validity of the underlying assumptions contained in the TS was not reviewed during the review and approval of the clearance order. Personnel trusted their knowledge of the TS rather than verifying the assumptions of the clearance order with the TS Bases.
Safety Significance
The EDG configuration consists of four shared EDGs. Each EDG is capable of sequentially starting and supplying the power requirements for one complete set of safeguards equipment for one reactor unit in the event of a design basis accident (DBA) and providing sufficient power to allow the second reactor unit to be placed in a safe shutdown condition. Each EDG provides the necessary power to cool the core and maintain containment pressure within the design value for a loss of coolant accident, coincident with a loss of offsite power, in addition to supplying sufficient power to shut down the unaffected unit.
At no point were all four EDGs inoperable. EDGs G-01 and G-03 were operable throughout the approximate four (4) hour event. Therefore, the ability to mitigate the consequences of a DBA on the operating unit and to maintain the opposite unit in the safe shutdown condition was not compromised. Normal power to buses 2A-05, 2A-06, 2B-03, and 2B-04 was provided for the duration of the event. Accordingly, the nuclear safety significance of this event was low.
Corrective Actions
A review of current and pending clearance orders was performed. This review found no currently hanging or planned clearance orders that have an adverselunanticipated plant impact. Additional actions, including revision of procedure guidance, are being tracked to completion in the corrective action program.
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