05000281/LER-2004-001-01, Regarding Switchyard Device Failure Results in a Reactor Trip

Regarding Switchyard Device Failure Results in a Reactor Trip

ML043280416
Person / Time
Site:	Surry
Issue date:	11/13/2004
From:	Blount R Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
04-401A LER 04-001-01
Download: ML043280416 (7)

LER-2004-001, Regarding Switchyard Device Failure Results in a Reactor Trip

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B)
2812004001R01 - NRC Website

text

10 CFR 50.73 Virginia Electric And Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 November 13, 2004 U. S. Nuclear Regulatory Commission Serial No.:

04-401A Attention: Document Control Desk SPS: TJN R2 Washington, D. C. 20555-0001 Docket No.:

50-281 License No.: DPR-37

Dear Sirs:

Pursuant to 10 CFR 50.73, Virginia Electric and Power Company hereby submits the following Supplemental Licensee Event Report applicable to Surry Power Station Unit 2.

Report No. 50-281/2004-001-01 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be forwarded to the Management Safety Review Committee for its review.

Very truly yous~

Richard H. Blount, Site Vice President Surry Power Station Enclosure Commitments contained in this letter:

1. The critical CCVTs for Unit 1 will be replaced in the Fall 2004 refueling outage.

2. Other switchyard CCVTs older than 20 years will be replaced and a monitoring and scheduled replacement program will be implemented to prevent future failures.

3. An evaluation will be conducted to verify that switchyard critical components and appropriate preventive maintenance activities are identified.

4. An evaluation and/or inspection will be conducted of the coating systems applied to carbon steel and stainless steel risk significant piping which have not been previously evaluated.

L1C.

Serial No.: 04-401A Docket No.: 50-281 cc: United States Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23 T85 Atlanta, Georgia 30303-8931 Mr. N. P. Garrett NRC Senior Resident Inspector Surry Power Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 6-30-2007 (6-2004)

Estimated burden per response to comly with this mandatory collection request 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported essons learned are ncorporated Into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIWPrivacy Service Branch (T-5 F52). U.S. Nuclear Re ulatory Commission, IrCENSEE EVENT REPORT (LER)

Washington, DC 20555-0001, or by Internet e-mail to Infocollectsenrc.gov, and to LICENSEE EVENT R Ad-a l

t

/the Desk Officer, Office of Information and RegulatoryAffairs, NEOB-10202 (3150-(See reverse for required number of digits/characters for each block) 0066). Office of Management and Budget, Washington, DC 20503. If a means used to Impose 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 respoand to. the Information collection.

3. PAGE SURRY POWER STATION, UNIT 2 05000 281 1 OF5

4. TITLE Switchyard Device Failure Results in a Reactor Trip

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED A

YR YR NUME R

EONO MONTH l DAY l YEAR FACILITY NAME DOCUMENT NUMBER

_NUMBER NO.

I_

05000 05 21 2004 2004

-. 001 --

01 11 13 2004 FACILITYNAME DOCUMENTNUMBER 1

05000

9.

11.THIS REPORT IS SUBMITTED PURSUANT TOTHE REQUIREMENTS OF10CFR§: (Checkallthatapply)

OPERATING MODE N

20.2201 (b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)

10. POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LEVEL 100%

20.2203(a)(1)

=

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

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

=

73.71 (a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71 (a)(5) 20.2203(a) (2) (ii) 50.36(c)(2) 50.73(a)(2)(v) (B)

OTHER 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v) (C) 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 20.2203(a)(2)(v)

X 50.73(a)(2)(i)(B)

X 50.73(a)(2)(vii) specify in Abstract below or 20.2203(a)(2)(vi) 50.73(a) (2)(i) (C) 50.73(a)(2)(viii)(A)

In NRC Foim 366A 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)

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

Richard H. Blount, Site Vice President (757) 365-2001CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE

_TO EPIX

_TOEPIX X

FK FD G080 Y

B BA PSP N

X BA JX W893 Y

II I

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION YES (H yes, complete 15. EXPECTED SUBMISSION DATE)

X I NO DATE ABSTRACT (Umit to 1400 spaces, L.e., apprordmately 15 single-spaced typewritten lines)

On May 21, 2004, at 2108 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02094e-4 months <br /> with Units 1 and 2 at 100% power, the Unit 2 main generator leads "A" phase Coupling Capacitor Voltage Transformer (CCVT) in the switchyard failed. The generator protective relays actuated, tripping the main generator, and resulting in trips of the turbine and reactor. Emergency systems functioned as required, including the Reactor Protection System (RPS) and Auxiliary Feedwater (AFW) System.

A Notification of Unusual Event was declared related to the switchyard CCVT failure. Unit 2 was stabilized at hot shutdown. The cause of the CCVT failure was age-related degradation. The failed CCVT was replaced. On May 22, 2004, following refill of the Emergency Condensate Storage Tank, an unisolable leak in a buried Unit 2 AFW recirculation line was discovered. The AFW system was declared inoperable. Further evaluations determined that the AFW system was capable of performing its intended function. The cause of the AFW piping leak was external galvanic corrosion of the buried carbon steel piping due to the failed corrosion protection. The recirculation line was rerouted. There were no significant safety consequences associated with this event. The automatic actuations of the RPS and the AFW are reportable pursuant to 10 CFR 50.73(a)(2)(iv)(A). The AFW leak is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(2)(vii).

NRC FORM 366 (6.2004)

(if more space is required, use additional copies of NRC Form 3664) (17) 1.0 DESCRIPTION OF THE EVENT On May 21, 2004, Units 1 and 2 at Surry Power Station were operating at 100% reactor power. At 1837 hours0.0213 days <br />0.51 hours <br />0.00304 weeks <br />6.989785e-4 months <br />, a 500 kilo-Volt (kV) switchyard trouble annunciator alarm was received in the main control room due to abnormal potential indication on the 500 kV generator Unit 2 leads.

Investigations found no physical damage on the potential measurement devices and no indication of oil residue on the Unit 2 main generator leads Coupling Capacitor Voltage Transformers (CCVTs). CCVTs, also referred to as Coupling Capacitor Potential Devices, step down switchyard voltage to provide voltage indication to switchyard protective relays and remote indicators. Voltage measurements indicated a degrading trend on the main generator leads "A" phase CCVT.

At 2108 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02094e-4 months <br />, during ongoing discussion concerning the need to take Unit 2 offline, the Unit 2 main generator leads "A" phase CCVT [EIIS: FD, FK] failed. The failure caused Unit 2 generator protective relays to actuate, tripping the main generator, and resulting in trips of the turbine and reactor. All three Auxiliary Feedwater (AFW) pumps [EIIS: P, BA] automatically started on low-low SG level as designed. The "C" SG AFW indicated no flow, but this was determined to be an indication only issue since wide range level in the associated SG was increasing at a rate comparable to the other two steam generators.

At 2109 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.024745e-4 months <br />, Security and Warehouse personnel notified the Main Control Room of an explosion and fire in the switchyard. At 2116 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.05138e-4 months <br />, the control room staff made a Notification of Unusual Event (NOUE) based on the "Confirmed report of unplanned explosion within Protected Area or Switchyard." The fire team responded and extinguished the last of the small fires in the switchyard by 2142 hours0.0248 days <br />0.595 hours <br />0.00354 weeks <br />8.15031e-4 months <br />. After verification that no further explosive hazards existed, the NOUE was terminated at 2256 hours0.0261 days <br />0.627 hours <br />0.00373 weeks <br />8.58408e-4 months <br />.

At 0028 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> on May 22, 2004, NRC notification was made in accordance with 10 CFR 50.72(b)(2)(iv)(B) for a 4-hour and 8-hour report due to automatic actuation of the Reactor Protection System (RPS) and AFW. This Licensee Event Report is provided pursuant to 10 CFR 50.73(a)(2)(iv)(A) for an event that resulted in automatic actuation of the Unit 2 RPS and AFW.

On May 22, 2004, with Unit 2 stabilized at hot shutdown (HSD), it was determined that a leak in an underground line was causing the Emergency Condensate Tank [EIIS: TK, BA]

to lose inventory at approximately 7.5 gallons per minute. Further investigation confirmed that the location was in an underground lube oil cooler minimum recirculation line [EIIS:

PSP, BA] common to all three Unit 2 AFW pumps. At 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br />, the AFW piping was declared inoperable and Unit 2 entered a 30-hour clock to cold shutdown (CSD). In addition, a 72-hour Unit 1 AFW cross-tie clock was entered. At 2229 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.481345e-4 months <br />, NRC (If more space is required, use additional copies of (if more space is required, use additinal copies of (if more space is required, use additional copies of NRC Form 366A) (17) 6.0 ACTIONS TO PREVENT RECURRENCE Critical CCVTs, which could cause a similar occurrence, were replaced for Unit 2. The critical CCVTs for Unit 1 will be replaced in the Fall 2004 refueling outage. Other switchyard CCVTs older than 20 years will be replaced and a monitoring and scheduled replacement program will be implemented to prevent future failures. An evaluation will be conducted to verify that switchyard critical components and appropriate preventive maintenance activities are identified.

The AFW recirculation lines on both units have been bypassed with piping which runs within a building and is therefore not subject to the environmental conditions which caused this pipe failure. An evaluation and/or inspection will be conducted of the coating systems applied to carbon steel and stainless steel risk significant piping which have not been previously evaluated.

Regarding the similar leak which occurred in the Unit 1 AFW recirculation line on April 27, 1992, the current corrective action program requires a complete and thorough cause analysis to be performed by the Root Cause Evaluation. Therefore, no additional corrective action was recommended due to significant improvements in the corrective action program which have been made over the last 12 years.

7.0 SIMILAR EVENTS

No similar event at Surry Power Station was found for the 500kV CCVT failure.

On February 10, 2001, during performance of a periodic AFW flow instrument channel check, "C" SG AFW flow indicator did not pass the test for AFW flow. The apparent cause evaluation determined that a Technipower sealed power supply module was degraded. The power supply module was replaced with a rebuilt spare module.

On April 27, 1992, a piping leak was identified in the Unit 1 AFW recirculation line. The corrective actions related to this leak were focused on bypassing the leaking line to stop the loss of water from the emergency condensate storage tank.

8.0 MANUFACTURER/MODEL NUMBER General Electric model CD31 B CCVT.

Technipower model 4111085001 power supply for flow indicator.

Schedule 40 carbon steel pipe (2 inch).

9.0 ADDITIONAL INFORMATION

On May 29, 2004, at 0623 hours0.00721 days <br />0.173 hours <br />0.00103 weeks <br />2.370515e-4 months <br />, Unit 2 returned on line.