05000338/LER-2016-001, Regarding Emergency Diesel Generators Automatic Start Due to Loss of Power to C Reserve Station Service Transformer

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Regarding Emergency Diesel Generators Automatic Start Due to Loss of Power to C Reserve Station Service Transformer
ML16099A386
Person / Time
Site: North Anna  
Issue date: 03/16/2016
From: Gerald Bichof
Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
16-035 LER 16-001-00
Download: ML16099A386 (4)
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LER-2016-001, Regarding Emergency Diesel Generators Automatic Start Due to Loss of Power to C Reserve Station Service Transformer
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)(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)(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)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
3382016001R00 - NRC Website
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text

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10CFR50.73 Virginia El~ctric and Power Company North Anna Power Station 1022 Haley Drive Mineral, Virginia 23117 March 16, 2016 Attention: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555~0001

Dear Sirs:

Serial No.:

16-035 NAPS:

MPW Docket No.: 50-338, 50-339 License No.: NPF-4, NPF-7 Pursuant to 1 OCFR50..73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to North Anna Power Station Units 1 and 2.

Report No; 50-338/2016-001-00 This report has been reviewed by the Facility.Safety Review Committee and will be forwarded to the, Management Safety Review Committee for its review.

Sincerely,

  • GYfZ~£ Site Vice President North Anna Power Station Enclosure Commitments containeq in this* letter: None*.

cc: * *.United States Nuclear Regulatory Commission Region II

  • Marquis One Tower

. 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, Georgia 30303-1257.

NRC Senior Resident Inspector North Anna Power Station

NRCFORM366 U.S. NUCLEAR REGULATORY COMl\\flSSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014)

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 />.

.;>~fl~(

Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections

~...... -i' LICENSEE EVENT REPORT (LER)

Branch (T-5 *F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, _DC digits/characters for each block) 20503. If a means used to impose an inforination collection does not display a currently valid OMB control number, the NRG may not conduct or sponsor, and a person is not required to respond to,

  • the information collection:
1. FACILITY NAME I
2. DOCKET NUMBER 3.PAGE North Anna Power Station, Units 1 and 2 05000338 1 OF 3 4.TITLE Emergency Diesel Generators Automatic Start Due to Loss of Power to "C" Reserve Station Service Transformer 5.EVENTDATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL* I REV FACILITYNAME
  • DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR North Anna Power Station 05000339 FACILITY NAME DOCKET NUMBER 01 23 2016 2016 -

001 - 00 03 16 2016 05000

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

D 20.2201(b)

- D 202203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 202201cd)

D 20.2203(a)(3)(ii)

D so.13(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A) 1 D 50.73(a)(2)(ii)(B)

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

D 20.2203(a)(1)

  • D 202203(a)(4)

D 20.2203(a)(2)(i)

D 50.36(c)(l)(i)(A)

D so.13(a)(2)(iii)

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

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

D so.36(c)(1)(ii)C~)

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

D 50.73(a)(2)(x)

D 202203(a)(2)(iii)

  • D so.36(c)(2)
  • D 50.73(a)(2)(v)(A)

D 73.71(a)(4)

D 20.2203(a)(2)(iv)

D so.46(a)(3)(ii)

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

D 13.11ca)(s) 100 D 50.73(a)(2)(v)(C)

D OTHER D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 20.2203(a)(2)(vi)

D so.13(a)(2)(i)(B)

D so.13c~)(2)(v)(D)

  • Specify in Abstract below or in 1.0 DESCRIPTION OF THE EVENT On January 23, 2016, at approximately 1703 hours0.0197 days <br />0.473 hours <br />0.00282 weeks <br />6.479915e-4 months <br />, Switchyard breaker L 102 (EllS System - EA, Component - BKR), supply to 34.5kV bus #3, tripped open from the*

Sulfur Hexafluoride (SF6) gas pressure switch. This resulted in the loss of "C" Reserve Station Service Transformer (RSST) (EllS System - EA, Component-XFMR) which suppljes "F" transfer and 2G intake structure 4160VAC buses (EllS System - EB, Component - BU). The 2G bus fast.transferred to the 1 G bus allowing all Unit 2 circulating water pumps to continue to run being supplied by Unit 1. The "F" transfer bus supplies the 1 H and 2J emergency buses (EllS System - EK, Component - BU).

Their associated Emergency Diesel Generators (EOG) (EllS System -EK, Component -

OG) started and loaded to recover those buses. The 1 H bus was swapped to its alternate supply from 1 B station service and the 1 H EOG was shutdown ahd returned to auto standby. Limiting actions on Unit 1 were cleared at that time. The 2J EOG continued to carry the 2J bus. At 1948 hours0.0225 days <br />0.541 hours <br />0.00322 weeks <br />7.41214e-4 months <br /> on January* 23, 2016, an 8-hour No'n-Emergency Report was made to the NRG in accordance with 10 CFR 50.72(b)(3)(iv)(A)

_as a condition that resulted in valid actuation of ESF.

3 As a result of the event, the Unit 2 Moisture Separator Reheater (MSR) fiow control valves (FCVs) (EllS System - SB, Component-FCV) went closed and reactor power reduced to approximately 96 percent. In addition, the Unit 1 "B" Charging pump (EllS System - CB, Component - P) auto-started due to the under-voltage condition on the 1 H bus. The pump was secured and returned to auto at 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br /> on January 23, 2016. *The MSR FCVs were reopened at *0332 hours on January 24, 2016. At 1528 hours0.0177 days <br />0.424 hours <br />0.00253 weeks <br />5.81404e-4 months <br /> on January 24, 2016, the "C" RSST was energized and normal power restored to the 2J Emergency bus. The 2J EOG was secured at 1541. hours. Repairs to breaker L 102 were com*pleted and the Unit 2 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting action was exited at 1706 hours0.0197 days <br />0.474 hours <br />0.00282 weeks <br />6.49133e-4 months <br /> on January 24, 2016.

2.0

  • SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS Units 1 and 2 continued to operate, as designed, foilowing the loss of offsite power. No significant safety consequences resulted from this event because the 1 H and 2J EOGs
  • powered the emergency busses, as designed. Offs1te power sources were restored in a timely manner and the associated EOGs were secured and returned to automatic. The health and safety of the public were not affected by* this event.

3.0 CAUSE

The direct cause for the opening of the L 102 breaker was an internal switch contact LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET 2.DOCKET

6. LER NUMBER YEAR I SEQUENTIAL I NUMBER 05000338 2016 001 REV.

NO.

00 3.PAGE OF failure due to moisture. Snow/moisture intrusion inside the cabinet likely shorted across the electrical terminals for the SF5 gas _pressure switch (63G) and caused the 63X relay to pick up, which tripped and locked out the breaker.

The SF6 pressure switch vendor was unable to find anything wrong with the calibration of the switch. Subject matter experts-(SME) within the company along with the breaker m*anufacturer were also unable to find anything physically wrong. with the switch.

4.0 IMMEDIATE CORRECTIVE ACTION(S)

The L 102 SF6 gas pressure switch was rep_laced and the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting action for Unit 2 was exited.

5.0 ADDITIONAL CORRECTIVE ACTIONS

In accordance with the manufacturer's and Dominion SME recommendations, all 34.5KV breakers* in the North Anna switchyard have had weather sealant applied to prevent moisture intrusion (rain/snow) where air gaps were noted to be around the conduit access plate and the mechanism access plate.at the bottom of the breaker cabinet which are the most likely intrusion areas.

Additionally the L 102 and L202 breakers had weather sealant applied to the area.where the breaker cabinet top meets the breaker cabinet side walls along the front and two sides..

6.0 ACTIONS TO PREVENT RECURRENCE The preventive maintenance procedure is being revised to include an additional check for snow and moisture intrusion path~* into cabinetS and seal as appropriate for the

  • breakers in question. Monitoring. of all the 34.5KV breakers for moisture intrusion will occur to determine if additional actions to seal the breakers are required for the remaining* nine (9) breakers. Inspections of the sealant will also be performed to ensure it remains intact. The monitoring period will be for approximately one year to allow the breakers to be exposed to all seasonal conditions.

. 7.0 SIMILAR EVENTS None 8.0 ADDITIONAL INFORMAT10N*

Component:

Manufacturer Model 1.0 DESCRIPTION OF THE EVENT On January 23, 2016, at approximately 1703 hours0.0197 days <br />0.473 hours <br />0.00282 weeks <br />6.479915e-4 months <br />, Switchyard breaker L 102 (EllS System - EA, Component - BKR), supply to 34.5kV bus #3, tripped open from the*

Sulfur Hexafluoride (SF6) gas pressure switch. This resulted in the loss of "C" Reserve Station Service Transformer (RSST) (EllS System - EA, Component-XFMR) which suppljes "F" transfer and 2G intake structure 4160VAC buses (EllS System - EB, Component - BU). The 2G bus fast.transferred to the 1 G bus allowing all Unit 2 circulating water pumps to continue to run being supplied by Unit 1. The "F" transfer bus supplies the 1 H and 2J emergency buses (EllS System - EK, Component - BU).

Their associated Emergency Diesel Generators (EOG) (EllS System -EK, Component -

OG) started and loaded to recover those buses. The 1 H bus was swapped to its alternate supply from 1 B station service and the 1 H EOG was shutdown ahd returned to auto standby. Limiting actions on Unit 1 were cleared at that time. The 2J EOG continued to carry the 2J bus. At 1948 hours0.0225 days <br />0.541 hours <br />0.00322 weeks <br />7.41214e-4 months <br /> on January* 23, 2016, an 8-hour No'n-Emergency Report was made to the NRG in accordance with 10 CFR 50.72(b)(3)(iv)(A)

_as a condition that resulted in valid actuation of ESF.

3 As a result of the event, the Unit 2 Moisture Separator Reheater (MSR) fiow control valves (FCVs) (EllS System - SB, Component-FCV) went closed and reactor power reduced to approximately 96 percent. In addition, the Unit 1 "B" Charging pump (EllS System - CB, Component - P) auto-started due to the under-voltage condition on the 1 H bus. The pump was secured and returned to auto at 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br /> on January 23, 2016. *The MSR FCVs were reopened at *0332 hours on January 24, 2016. At 1528 hours0.0177 days <br />0.424 hours <br />0.00253 weeks <br />5.81404e-4 months <br /> on January 24, 2016, the "C" RSST was energized and normal power restored to the 2J Emergency bus. The 2J EOG was secured at 1541. hours. Repairs to breaker L 102 were com*pleted and the Unit 2 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting action was exited at 1706 hours0.0197 days <br />0.474 hours <br />0.00282 weeks <br />6.49133e-4 months <br /> on January 24, 2016.

2.0

  • SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS Units 1 and 2 continued to operate, as designed, foilowing the loss of offsite power. No significant safety consequences resulted from this event because the 1 H and 2J EOGs
  • powered the emergency busses, as designed. Offs1te power sources were restored in a timely manner and the associated EOGs were secured and returned to automatic. The health and safety of the public were not affected by* this event.

3.0 CAUSE

The direct cause for the opening of the L 102 breaker was an internal switch contact LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET 2.DOCKET

6. LER NUMBER YEAR I SEQUENTIAL I NUMBER 05000338 2016 001 REV.

NO.

00 3.PAGE OF failure due to moisture. Snow/moisture intrusion inside the cabinet likely shorted across the electrical terminals for the SF5 gas _pressure switch (63G) and caused the 63X relay to pick up, which tripped and locked out the breaker.

The SF6 pressure switch vendor was unable to find anything wrong with the calibration of the switch. Subject matter experts-(SME) within the company along with the breaker m*anufacturer were also unable to find anything physically wrong. with the switch.

4.0 IMMEDIATE CORRECTIVE ACTION(S)

The L 102 SF6 gas pressure switch was rep_laced and the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting action for Unit 2 was exited.

5.0 ADDITIONAL CORRECTIVE ACTIONS

In accordance with the manufacturer's and Dominion SME recommendations, all 34.5KV breakers* in the North Anna switchyard have had weather sealant applied to prevent moisture intrusion (rain/snow) where air gaps were noted to be around the conduit access plate and the mechanism access plate.at the bottom of the breaker cabinet which are the most likely intrusion areas.

Additionally the L 102 and L202 breakers had weather sealant applied to the area.where the breaker cabinet top meets the breaker cabinet side walls along the front and two sides..

6.0 ACTIONS TO PREVENT RECURRENCE The preventive maintenance procedure is being revised to include an additional check for snow and moisture intrusion path~* into cabinetS and seal as appropriate for the

  • breakers in question. Monitoring. of all the 34.5KV breakers for moisture intrusion will occur to determine if additional actions to seal the breakers are required for the remaining* nine (9) breakers. Inspections of the sealant will also be performed to ensure it remains intact. The monitoring period will be for approximately one year to allow the breakers to be exposed to all seasonal conditions.

. 7.0 SIMILAR EVENTS None 8.0 ADDITIONAL INFORMAT10N*

Component:

Manufacturer Model 63G pressure switch Solari 6TC Bulb type.

3

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