05000281/LER-2011-002, For Surry Power Station, Unit 2, Regarding Spurious Safety Injection Results in Exceeding Pressurizer Heatup Rate

For Surry Power Station, Unit 2, Regarding Spurious Safety Injection Results in Exceeding Pressurizer Heatup Rate

ML11214A215
Person / Time
Site:	Surry
Issue date:	07/25/2011
From:	Gerald Bichof Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
11-399 LER 11-002-00
Download: ML11214A215 (6)

LER-2011-002, For Surry Power Station, Unit 2, Regarding Spurious Safety Injection Results in Exceeding Pressurizer Heatup Rate

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(A) 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)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2812011002R00 - NRC Website

text

1 OCFR50.73 Virginia Electric and Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 July 25, 2011 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001 Serial No.:

SPS:

Docket No.:

License No.:

11-399 JSA 50-281 DPR-37

Dear Sirs:

Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to Surry Power Station Unit 2.

Report No. 50-281/2011-002-00 This report has been reviewed by the Station Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee for its review.

Very truly yours, Gerald T. Bisb-hoe, Site Vice President Surry Power Station Enclosure Commitment contained in this letter: None

cc: U.S. Nuclear Regulatory Commission, Region II Marquis One Tower, Suite 1200 245 Peachtree Center Ave., NE Atlanta, GA 30303-1257 NRC Senior Resident Inspector Surry Power Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES 10/31/2013 (10-2011)

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

13. PAGE Surry Power Station, Unit 2 05000- 281I 1 OF 4

4. TITLE Spurious Safety Injection Results in Exceeding Pressurizer Heatup Rate

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR SEQUENTIAL REV M

DFACILITY NAME DOCKET NIMBER YEAR NUMBER NO.

MONTH DAY YEAR 05000 05 26 11 2011 -

002 -

00 07 25 11 FACILITY NAME DOCKET NUMBER 105000

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

[:

20.2201(b)

El 20.2203(a)(3)(i) jJ 50.73(a)(2Xi)(C)

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50.73(a)(2)(vii)

N jJ 20.2201(d)

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20.2203(a)(3Xii)

El 50.73(a)(2)(iiXA)

E] 50.73(a)(2)(viii)(A)

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20.2203(a)(4)

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50.73(a)(2Xii)(a)

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

_ _ 20.2203(a)(2)(i)

EJ 50.36(cXl)(i)(A)

EJ 50.73(a)(2)(iii) i]

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

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

E] 50.36(c)(1Xii)(A)

El 50.73(aX2)(iv)(A)

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50.73(a)(2)(x)

EJ 20.2203(a)(2)(iii)

EJ 50.36(c)(2)

EJ 50.73(a)(2)(v)(A) 11 73.71(a)(4) 000%

[]20.2203(a)(2)(iv)

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50.46(a)(3)(ii)

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50.73(a)(2)(v)(a)

E:] 73.71(a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)

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

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

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

Specify in Abstract below IZI 2

03(a)(vi 50.73(a)(2)(v)(D) or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)

B. L. Stanley, Director Safety and Licensing (757) 365-2003MANU-REPORTABLE CU SYST COPONNT NU-REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX X

AB PZR W120 Y

B BQ RLY W120 Y

14. SUPPLEMENTAL REPORT EXPECTED B

15. EXPECTED MONTH DAY YEAR El YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 1 I NO SUBMISSION I

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

On May 26, 2011, at 1524 hours0.0176 days <br />0.423 hours <br />0.00252 weeks <br />5.79882e-4 months <br />, with Surry Power Station Unit 1 at 100% power and Unit 2 at intermediate shutdown (ISD), a spurious actuation of the Unit 2 Train B of the Safety Injection (SI) system occurred during performance of the Consequence Limiting Safeguards (CLS) Logic Test.

The cause of the spurious SI was a failed relay. The relay was replaced and sent to the vendor for a failure analysis. Plant systems and components responding to the Train B SI signal started and functioned as designed. Train B SI was reset and the affected systems were restored to their pre-event configuration. The reactor was maintained at ISD and the health and safety of the public were not affected. At 1531 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.825455e-4 months <br />, the Pressurizer liquid space temperature began to increase and over a 45 minute period, the Pressurizer heatup rate exceeded the Technical Specification (TS) limit of 100OF per hour due to Pressurizer heaters remaining energized during the event. Also contributing to the temperature increase was the dynamic mixing caused by the insurge coupled with the warmer fluid already in the pressurizer when the SI initiated. This report is being submitted pursuant to 1 OCFR50.73(a)(2)(iv)(A) for automatic actuation of an emergency core cooling system and actuation of an EDG, as well as 1 OCFR50.73(a)(2)(i)(B) for operation or condition prohibited by TS.

1.0 DESCRIPTION OF THE EVENT On May 26, 2011, at 1524 hours0.0176 days <br />0.423 hours <br />0.00252 weeks <br />5.79882e-4 months <br />, with Surry Power Station Unit 1 at 100% power and Unit 2 at intermediate shutdown (ISD) (-2500F and -286 psig) following a scheduled refueling, a spurious actuation of the Unit 2 Train B of the Safety Injection (SI) [EIIS-BQ] system occurred during performance of the Consequence Limiting Safeguards (CLS) Logic Test. Technicians were completing the test and depressed the test terminate push button in the HI CLS Rack Train B when the Train B SI actuation occurred. The cause of the spurious SI was a failed relay.

Plant systems and components responding to the Unit 2 Train B SI signal started and functioned as designed except those systems and components not required to be operable below reactor coolant system (RCS) temperature of 350°F and RCS pressure of 450 psig. One high head pump [EIIS-AB-P] was operating and two redundant pumps were in the pull to lock position. The Train B SI motor operated valves [EIIS-BQ-V] re-aligned, providing flow to the RCS Cold Legs from the Refueling Water Storage Tank [EIIS-BE-TK]. Auxiliary Feedwater (AFW) pump motor operated valves [EIIS-BA-V] opened but no flow was delivered to the Steam Generators [EIIS-SB-SG] since the AFW pumps [EIIS-BA-P] were in pull to lock.

The Train B containment isolation valves [EIIS-NH-ISV] closed, isolating the B Residual Heat Removal (RHR) heat exchanger [EIIS-BP-HX]. Shutdown cooling was previously being provided by the A RHR train and was therefore uninterrupted.

One train of Auxiliary Ventilation [EIIS-NF-VLR] actuated and Emergency Diesel Generator (EDG) [EIIS-EK-DG] #3 started but did not load since its associated Emergency Bus remained energized by offsite power.

Pressurizer level was at 20.8% when the Unit 2 Train B SI occurred. The RCS insurge into the Pressurizer due to SI flow lowered the liquid space temperature from 428 0F to 3050F. At 1526 hours0.0177 days <br />0.424 hours <br />0.00252 weeks <br />5.80643e-4 months <br />, Train B SI was reset and the affected systems were restored to their pre-event configuration. At 1531 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.825455e-4 months <br />, the Pressurizer liquid space temperature began to increase and over a 45 minute period rose from 305°F to 425 0F exceeding the TS 3.1.B.3 Pressurizer heatup rate limit of less than 100OF per hour.

This report is being submitted pursuant to 1 OCFR50.73(a)(2)(iv)(A) for automatic actuation of an emergency core cooling system and actuation of an EDG, as well as 1 OCFR50.73(a)(2)(i)(B) for operation prohibited by TSs when the Unit 2 RCS Pressurizer exceeded the heatup rate specified by TS 3.1..B.3.

2.0

SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS

Automatic safety systems performed as designed. The operators properly diagnosed the nature of the spurious SI signal and transitioned through abnormal procedures appropriately. The spurious SI event did not present a challenge to theU.S. NUCLEAR REGULATORY COMMISSION (10-2011)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE YEAR SEQUENTIAL REV Surry Power Station 05000- 281 NUMBER NO.

3 of 4 2011 002 00 safety of the plant and an evaluation considered the event to be of low safety significance. The unit was maintained stable at ISD. There were no radiation releases due to these events. Therefore, the health and safety of the public were not affected at any time during this event. Based on a technical evaluation, the Pressurizer had no adverse consequence due to exceeding the Pressurizer heatup temperature limit.

3.0

CAUSE

Troubleshooting determined that the cause of the May 26, 2011 Unit 2 spurious actuation of SI was a failed relay (a single contact was failed open when it should have been closed). The failure occurred during performance of the CLS Logic Test when the test terminate push button was depressed. The relay had been replaced during the current Unit 2 refueling outage. When the failed relay was removed, the moveable contact was found to be no longer aligned with the stationary contact. A vendor failure analysis will evaluate the cause of the infant mortality failure.

The Pressurizer liquid space temperature rapid increase was the result of the Pressurizer heaters remaining energized during the event. Also contributing to the temperature increase was the dynamic mixing caused by the insurge coupled with the warmer fluid already in the pressurizer when the SI initiated.

4.0 IMMEDIATE CORRECTIVE ACTION(S)

Control room operators acted promptly to maintain the unit stable at ISD in accordance with abnormal operating procedures. Unit 2 Train B SI was reset and the affected systems were restored to their pre-event configuration.

5.0

ADDITIONAL CORRECTIVE ACTIONS

The failed CLS Train B relay was replaced and sent to the vendor for a failure analysis.

An evaluation of the Pressurizer transient concluded there were no adverse effects on the Pressurizer and that the Pressurizer is capable of performing its design function.

6.0 ACTIONS TO PREVENT RECURRENCE A cause evaluation will be performed for the CLS relay pending the vendor failure analysis.

7.0 ; SIMILAR EVENTS NoneU. S. NUCLEAR REGULATORY COMMISSION (10-2011)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE YEAR SEQUENTIAL REV Surry Power Station 05000- 281 NUMBER NO.

4 of 4 2011 002 00 8.0 MANUFACTURER/MODEL NUMBER CLS Train B relay: Westinghouse Electric Corporation/ NBFD65NR, 9084A70G01 9.0

ADDITIONAL INFORMATION

Unit 1 was at 100% power and remained unaffected by the Unit 2 suprious SI.

Unit 2 continued with the scheduled refueling outage.