text

LER-2015-001, Regarding Diesel Generator Start Resulting from Switchyard Protective Relay Actuation
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation; 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded; 10 CFR 50.73(a)(2); 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)(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
	2502015001R00 - NRC Website
	v • d • e

Regarding Diesel Generator Start Resulting from Switchyard Protective Relay Actuation
	ML16053A096
Person / Time
Site:	Turkey Point
Issue date:	01/19/2016
From:	Domingos C; Florida Power & Light Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	L-2016-014 LER 15-001-00
	Download: ML16053A096 (4)
	v • d • e

-

FPL.

L-20 16-014 10 CFR § 50.73 January 19, 2016 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:

Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2015-001-00 Date of Event: November 18, 2015 Diesel Generator Start Resulting From Switchyard Protective Relay Actuation The attached Licensee Event Report 05000250/2015-001-00 is submitted pursuant to 10 CFR 50.73 (a)(2)(iv)(A) due to automatic actuation of the emergency ac power system.

If there are any questions, then please call Mr. Mitch Guth at 305-246-6698.

Sincerely, Chris Domingos Plant General Manager Turkey Point Nuclear Plant Afttachment cc:

Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Homestead, FL 33035

NRC FORM 368 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/3112017

-(02.-2014*i--

Estimated burden per response to comnply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

¢a"*"r"%Reported lessons learned are incorporated into the licensing process and fed back to industry.

"* t****.Send comments regarding burden estimate to the FOIA, Privacy and Information Collections

==

Branch (T-5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by I.,, LICENSEE EVENT REPORT (LER) intemect a-mail to lnfocollects.Reaource@nrc.gov, and to the Desk Officer, Office of Information and (SeePag 2 fr rquied nmbe ofRegulatory Affairs, NEON-10202, (3150-0104), Office of Management and Budget, Washington, DC (Se Pa e 2 or equied umbe of20503.

If a means used to impose an information collection does not display a currently valid 0MB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a parson is not required to respond to, the information collection.

3. PAGE Turkey Point Unit 3 05000250 1

of 3

4. TITLE Diesel Generator Start Resulting From Switchyard Protective Relay Actuation

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEUETIL evFACILITY NAME T

DOCKET NUMBER MONTH DAY YEAR YEAR SEQENTALHevDAY YEAR I INUMBER NO.

MOT

__I FACILITY NAME DOCKET NUMBER 11 18 2015 2015 -

001 -

00 1

19 2016

9. OPERATING MODE

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

D]

20.2201(d)

[] 20.2203(a)(3)(ii)

D]

50.73(a)(2)(ii)(A)

[] 50.73(a)(2)(vrii)(A D] 20.2203(a)(2)(i)

[] 50.36(c)(1)(i)(A)

D]

50.73(a)(2)(iii)

[]

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

10. POWER LEVEL D]

20.2203(a)(2)(ii)

D]

50.36(c)(1)(ii)(A)

[] 50.73(a)(2)(iv)(A)

[]

50.73(a)(2)(x)

D] 20.2203(a)(2)(iii)

[] 50.36(c)(2)

[] 50.73(a)(2)(v)(A)

III 73.71 (a)(4)

D] 20.2203(a)(2)(iv)

[] 50.46(a)(3)(ii)

D]

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

[] 73.71 (a)(5) 0%

20.2203(a)(2)(v)

[] 50.73(a)(2)(i)(A)

[]

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

[]

OTHER

[] 2.223(a(2)vi)

[]

5.73a)()(i(B)

[]

5.73a)()(v(D)Specify in Abstract below or in D

20220(a)2)Cv)

D 50.3(a(2)()(B D

0.73a)()(v(D)NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACIITY AMETELEPHONE NUMBER (Include Area Code)

MitchGuth 305-246-6698CASE SSTM OPOEN ANU-POT LE*IcUS SYTE CoMPOeNT MANU-RPOR CAS YTM CMOET FACTURER TO EPIX mi______FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSSION YES (If yes, Complete 15. EXPECTED SUBMISSION DATE)

X NO DATE ABSTRACT (Limit to 1400 spaces i e, approximately 15 single-spaced typewritten lines)

On November 18, 2015 at approximately 23:33 hours with Unit 3 in Mode 5 during a refueling outage, the 3B Emergency Diesel Generator (EDG) automatically started and loaded on the 3B bus. The cause of the EDG start was a loss of offsite power to the 3A and 3B 4160V busses when the supply breakers to the Unit 3 Startup Transformer automatically opened due to an unexpected protective relay actuation in the Unit 3 switchyard. When the 3A and 3B busses were deenergized, the 3B EDG re-energized the 3B bus, but the 3A sequencer was out of service for preplanned work so the 3A bus was not immediately reenergized. The unit remained in Mode 5 with core decay heat removal provided by the 3B Residual Heat Removal loop.

The cause of the event was the unexpected actuation of the protective relay during switchyard work.

The automatic EDG start is being reported pursuant to 10 CFR 50.73(a)(2)(iv)(A).U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01/31/2017

,(C2-201V4'...

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

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

g*

/°*

Send comments regarding hurden estimate to the FOIA, Pdvacy and Information Collections

.¢*

Branch (1".5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by S

LICENSEE EVENT REPORT (LER) internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC

"*"CONTINUATION SHEET 20583. Ifsa means used to impose an information collecton doss not display a currently vali 0MB control namber, the NRC may not conduct or sponsor, and a pemson is not required to respond to, the information collection.

1. FACILITY NAME

2. DOCKET

6. LER NUMER

3. PAGE YER SEQUENTIAL REV Turkey Point Unit 3 05000250 NUBR N.

2 of 3

2015 --

001 00 DESCRIPTION OF THE EVENT On November 18, 2015 at approximately 23:33 hours with Unit 3 in Mode 5 during a refueling outage (RFO), a valid actuation signal was generated for the 3A and 3B Emergency Diesel Generators (EDGs)

[EIIS: EK, DG] when the supply breakers [EJIS: FK, BKR] to the Unit 3 Start-up Transformer (SUT)

[EJIS: EA, XFMR] automatically opened resulting in a loss of offsite power to the 3A and 3B 4160 V buses [EJIS: EA, BU]. The loss of offsite power (LOOP) was caused by an unexpected actuation of the Breaker Failure Trip relay [EJIS: FK, 87] protection scheme in the Turkey Point switchyard. The 3B Emergency Diesel Generator (EDG) automatically started as required in response to the busses being deenergized. The 3B bus was automatically sequenced on to the 3B EDG. The 3A sequencer was out of service for preplanned work during the event requiring the 3A EDG to be manually started and connected to the 3A bus. The unit remained in Mode 5 with core decay heat removal provided by the 3B Residual Heat Removal loop [EJIS: BP, P].

Event Notification 51551 was made to the NRC Operations Center for both the declaration of an unusual event and for a valid actuation of the emergency ac electrical power system in accordance with 10 CFR 50.72(b)(3)(iv)(A). This report is in accordance with.10 CFR 50.73(a)(2)(iv)(A) due to valid actuations of the emergency ac power system.

CAUSES OF THE EVENT The direct cause of the Unit 3 LOOP was actuation of the GE-B30 Breaker Failure Trip relay protection scheme. Subsequent investigation revealed that a combination of conditions resulted in a spurious trip of the protective relay: 1) a historical modification in the switchyard by the transmission system operator did not properly isolate abandoned circuits which resulted in a ground in the circuit; 2) the presence of long unshielded copper conductors in the control circuits; and 3) a new relay being installed during the RFO that is more sensitive. During a switchyard switching evolution, a ground signal was introduced on the switchyard dc system which, coupled with the long unshielded copper conductor, initiated the spurious trip of the new relay.

ANALYSIS OF THE EVENT

During the refueling outage, the Unit 3 SUT Breaker Failure Trip protection scheme was modified by the transmission system operator to physically separate it from the Unit 4 SUT protection scheme which were both housed in a common panel [EIIS: FK, PL] in the switchyard. A new panel and digital relays were installed to update the system, eliminating the electromechanical relays [EIIS: FK, 87].

Subsequent troubleshooting identified the presence of a dc ground on switchyard breaker [EIIS: FK, BKR] 8W43 that was abandoned in 2006, although the control power circuitry terminations in breaker 8W43 were not removed. Further contributing to this event is the fact that the new GE-B30 digital relay is more sensitive than the electromechanical relay it replaced, and that the existing unshielded copper cabling in the Breaker Failure Trip relay circuit made it more susceptible to interference. TroubleshootingU.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01/31/2017

*(0-201,¥.*Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

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

;Z '5 Send comments regardiog burden estimate to the FOIA, Pdvacy and Information Collections

,i*#*Branch (T-5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT REPORT (LER) intemet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Offce of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office ot Management and Budget, Washington, DC

"*"CONTINUATION SHEET 20503. Ifsa means used to impose an information collection does not display a currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME

2. DOCKET

6. LER NUMER

3. PAGE YEAR SEQUENTIAL REV Turkey Point Unit 3 05000250 NUBR N.

3 of3 2015 --

001 00 discovered that the long cable runs of unshielded copper wire used for the dc inputs had an induced voltage. Together, these reductions in operating margin contributed to the unexpected actuation of the GE-B30 Breaker Failure Trip protection during the implementation of the switching order on November 18, 2015.

ANALYSIS OF SAFETY SIGNIFICANCE At the time of the event, Unit 3 was in Mode 5 following a core reload. The 3B EDG automatically started as required in response to the LOOP. The 3B bus was automatically sequenced on to the 3B EDG.

The 3A sequencer was out of service during the event requiring the 3A EDG to be manually started and connected to the 3A bus. The unit remained in Mode 5 with decay heat removal provided by the 3B Residual Heat Removal loop. Plant response was as expected. All systems responded as designed. As a result, the safety significance of the event is considered to be low.

CORRECTIVE ACTIONS

Corrective actions are described in condition report AR 2092653 and include:

1. Completed implementation of a permanent design change via EC 285281 for Unit 3 that eliminated the Breaker Failure Trip protection scheme provided by the GE-B30 relay.

2. Strengthening the FPL process for abandoning equipment in the nuclear switchyard.

3. Performance of an extent of cause review on abandoned equipment in the switchyard for items left connected to operating equipment.

ADDITIONAL INFORMATION

EIIS Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].

FAILED COMPONENTS IDENTIFIED: None.

PREVIOUS SIMILAR EVENTS

None in the last five years.

FPL.

L-20 16-014 10 CFR § 50.73 January 19, 2016 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:

Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2015-001-00 Date of Event: November 18, 2015 Diesel Generator Start Resulting From Switchyard Protective Relay Actuation The attached Licensee Event Report 05000250/2015-001-00 is submitted pursuant to 10 CFR 50.73 (a)(2)(iv)(A) due to automatic actuation of the emergency ac power system.

If there are any questions, then please call Mr. Mitch Guth at 305-246-6698.

Sincerely, Chris Domingos Plant General Manager Turkey Point Nuclear Plant Afttachment cc:

Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Homestead, FL 33035

NRC FORM 368 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/3112017

-(02.-2014*i--

Estimated burden per response to comnply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

¢a"*"r"%Reported lessons learned are incorporated into the licensing process and fed back to industry.

"* t****.Send comments regarding burden estimate to the FOIA, Privacy and Information Collections

==

Branch (T-5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by I.,, LICENSEE EVENT REPORT (LER) intemect a-mail to lnfocollects.Reaource@nrc.gov, and to the Desk Officer, Office of Information and (SeePag 2 fr rquied nmbe ofRegulatory Affairs, NEON-10202, (3150-0104), Office of Management and Budget, Washington, DC (Se Pa e 2 or equied umbe of20503.

If a means used to impose an information collection does not display a currently valid 0MB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a parson is not required to respond to, the information collection.

3. PAGE Turkey Point Unit 3 05000250 1

of 3

4. TITLE Diesel Generator Start Resulting From Switchyard Protective Relay Actuation

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEUETIL evFACILITY NAME T

DOCKET NUMBER MONTH DAY YEAR YEAR SEQENTALHevDAY YEAR I INUMBER NO.

MOT

__I FACILITY NAME DOCKET NUMBER 11 18 2015 2015 -

001 -

00 1

19 2016

9. OPERATING MODE

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

D]

20.2201(d)

[] 20.2203(a)(3)(ii)

D]

50.73(a)(2)(ii)(A)

[] 50.73(a)(2)(vrii)(A D] 20.2203(a)(2)(i)

[] 50.36(c)(1)(i)(A)

D]

50.73(a)(2)(iii)

[]

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

10. POWER LEVEL D]

20.2203(a)(2)(ii)

D]

50.36(c)(1)(ii)(A)

[] 50.73(a)(2)(iv)(A)

[]

50.73(a)(2)(x)

D] 20.2203(a)(2)(iii)

[] 50.36(c)(2)

[] 50.73(a)(2)(v)(A)

III 73.71 (a)(4)

D] 20.2203(a)(2)(iv)

[] 50.46(a)(3)(ii)

D]

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

[] 73.71 (a)(5) 0%

20.2203(a)(2)(v)

[] 50.73(a)(2)(i)(A)

[]

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

[]

OTHER

[] 2.223(a(2)vi)

[]

5.73a)()(i(B)

[]

5.73a)()(v(D)Specify in Abstract below or in D

20220(a)2)Cv)

D 50.3(a(2)()(B D

0.73a)()(v(D)NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACIITY AMETELEPHONE NUMBER (Include Area Code)

MitchGuth 305-246-6698CASE SSTM OPOEN ANU-POT LE*IcUS SYTE CoMPOeNT MANU-RPOR CAS YTM CMOET FACTURER TO EPIX mi______FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSSION YES (If yes, Complete 15. EXPECTED SUBMISSION DATE)

X NO DATE ABSTRACT (Limit to 1400 spaces i e, approximately 15 single-spaced typewritten lines)

On November 18, 2015 at approximately 23:33 hours with Unit 3 in Mode 5 during a refueling outage, the 3B Emergency Diesel Generator (EDG) automatically started and loaded on the 3B bus. The cause of the EDG start was a loss of offsite power to the 3A and 3B 4160V busses when the supply breakers to the Unit 3 Startup Transformer automatically opened due to an unexpected protective relay actuation in the Unit 3 switchyard. When the 3A and 3B busses were deenergized, the 3B EDG re-energized the 3B bus, but the 3A sequencer was out of service for preplanned work so the 3A bus was not immediately reenergized. The unit remained in Mode 5 with core decay heat removal provided by the 3B Residual Heat Removal loop.

The cause of the event was the unexpected actuation of the protective relay during switchyard work.

The automatic EDG start is being reported pursuant to 10 CFR 50.73(a)(2)(iv)(A).U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01/31/2017

,(C2-201V4'...

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

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

g*

/°*

Send comments regarding hurden estimate to the FOIA, Pdvacy and Information Collections

.¢*

Branch (1".5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by S

LICENSEE EVENT REPORT (LER) internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC

"*"CONTINUATION SHEET 20583. Ifsa means used to impose an information collecton doss not display a currently vali 0MB control namber, the NRC may not conduct or sponsor, and a pemson is not required to respond to, the information collection.

1. FACILITY NAME

2. DOCKET

6. LER NUMER

3. PAGE YER SEQUENTIAL REV Turkey Point Unit 3 05000250 NUBR N.

2 of 3

2015 --

001 00 DESCRIPTION OF THE EVENT On November 18, 2015 at approximately 23:33 hours with Unit 3 in Mode 5 during a refueling outage (RFO), a valid actuation signal was generated for the 3A and 3B Emergency Diesel Generators (EDGs)

[EIIS: EK, DG] when the supply breakers [EJIS: FK, BKR] to the Unit 3 Start-up Transformer (SUT)

[EJIS: EA, XFMR] automatically opened resulting in a loss of offsite power to the 3A and 3B 4160 V buses [EJIS: EA, BU]. The loss of offsite power (LOOP) was caused by an unexpected actuation of the Breaker Failure Trip relay [EJIS: FK, 87] protection scheme in the Turkey Point switchyard. The 3B Emergency Diesel Generator (EDG) automatically started as required in response to the busses being deenergized. The 3B bus was automatically sequenced on to the 3B EDG. The 3A sequencer was out of service for preplanned work during the event requiring the 3A EDG to be manually started and connected to the 3A bus. The unit remained in Mode 5 with core decay heat removal provided by the 3B Residual Heat Removal loop [EJIS: BP, P].

Event Notification 51551 was made to the NRC Operations Center for both the declaration of an unusual event and for a valid actuation of the emergency ac electrical power system in accordance with 10 CFR 50.72(b)(3)(iv)(A). This report is in accordance with.10 CFR 50.73(a)(2)(iv)(A) due to valid actuations of the emergency ac power system.

CAUSES OF THE EVENT The direct cause of the Unit 3 LOOP was actuation of the GE-B30 Breaker Failure Trip relay protection scheme. Subsequent investigation revealed that a combination of conditions resulted in a spurious trip of the protective relay: 1) a historical modification in the switchyard by the transmission system operator did not properly isolate abandoned circuits which resulted in a ground in the circuit; 2) the presence of long unshielded copper conductors in the control circuits; and 3) a new relay being installed during the RFO that is more sensitive. During a switchyard switching evolution, a ground signal was introduced on the switchyard dc system which, coupled with the long unshielded copper conductor, initiated the spurious trip of the new relay.

ANALYSIS OF THE EVENT

During the refueling outage, the Unit 3 SUT Breaker Failure Trip protection scheme was modified by the transmission system operator to physically separate it from the Unit 4 SUT protection scheme which were both housed in a common panel [EIIS: FK, PL] in the switchyard. A new panel and digital relays were installed to update the system, eliminating the electromechanical relays [EIIS: FK, 87].

Subsequent troubleshooting identified the presence of a dc ground on switchyard breaker [EIIS: FK, BKR] 8W43 that was abandoned in 2006, although the control power circuitry terminations in breaker 8W43 were not removed. Further contributing to this event is the fact that the new GE-B30 digital relay is more sensitive than the electromechanical relay it replaced, and that the existing unshielded copper cabling in the Breaker Failure Trip relay circuit made it more susceptible to interference. TroubleshootingU.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01/31/2017

*(0-201,¥.*Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days 0.0222 hours 1.322751e-4 weeks 3.044e-5 months .

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

;Z '5 Send comments regardiog burden estimate to the FOIA, Pdvacy and Information Collections

,i*#*Branch (T-5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT REPORT (LER) intemet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Offce of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office ot Management and Budget, Washington, DC

"*"CONTINUATION SHEET 20503. Ifsa means used to impose an information collection does not display a currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME

2. DOCKET

6. LER NUMER

3. PAGE YEAR SEQUENTIAL REV Turkey Point Unit 3 05000250 NUBR N.

3 of3 2015 --

001 00 discovered that the long cable runs of unshielded copper wire used for the dc inputs had an induced voltage. Together, these reductions in operating margin contributed to the unexpected actuation of the GE-B30 Breaker Failure Trip protection during the implementation of the switching order on November 18, 2015.

ANALYSIS OF SAFETY SIGNIFICANCE At the time of the event, Unit 3 was in Mode 5 following a core reload. The 3B EDG automatically started as required in response to the LOOP. The 3B bus was automatically sequenced on to the 3B EDG.

The 3A sequencer was out of service during the event requiring the 3A EDG to be manually started and connected to the 3A bus. The unit remained in Mode 5 with decay heat removal provided by the 3B Residual Heat Removal loop. Plant response was as expected. All systems responded as designed. As a result, the safety significance of the event is considered to be low.

CORRECTIVE ACTIONS

Corrective actions are described in condition report AR 2092653 and include:

1. Completed implementation of a permanent design change via EC 285281 for Unit 3 that eliminated the Breaker Failure Trip protection scheme provided by the GE-B30 relay.

2. Strengthening the FPL process for abandoning equipment in the nuclear switchyard.

3. Performance of an extent of cause review on abandoned equipment in the switchyard for items left connected to operating equipment.

ADDITIONAL INFORMATION

EIIS Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].

FAILED COMPONENTS IDENTIFIED: None.

PREVIOUS SIMILAR EVENTS

None in the last five years.

05000250/LER-2015-001, Regarding Diesel Generator Start Resulting from Switchyard Protective Relay Actuation

Contents

text

ANALYSIS OF THE EVENT

CORRECTIVE ACTIONS

ADDITIONAL INFORMATION

PREVIOUS SIMILAR EVENTS

ANALYSIS OF THE EVENT

CORRECTIVE ACTIONS

ADDITIONAL INFORMATION

PREVIOUS SIMILAR EVENTS

Navigation menu

05000250/LER-2015-001, Regarding Diesel Generator Start Resulting from Switchyard Protective Relay Actuation

text

ANALYSIS OF THE EVENT

CORRECTIVE ACTIONS

ADDITIONAL INFORMATION

PREVIOUS SIMILAR EVENTS

ANALYSIS OF THE EVENT

CORRECTIVE ACTIONS

ADDITIONAL INFORMATION

PREVIOUS SIMILAR EVENTS

Navigation menu

Search