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{{Adams
#REDIRECT [[05000324/LER-2015-002]]
| number = ML15329A374
| issue date = 11/16/2015
| title = LER 15-002-01 for Brunswick, Unit 1, Regarding Emergency Diesel Generator Loss of Safety Function
| author name = Gideon W R
| author affiliation = Duke Energy Progress, Inc
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000324, 05000325
| license number = DPR-062, DPR-071
| contact person =
| case reference number = BSEP 15-0084
| document report number = LER 15-002-01
| document type = Letter, Licensee Event Report (LER)
| page count = 7
}}
 
=Text=
{{#Wiki_filter:~(ENERGY William R. GideonVice President Brunswick Nuclear PlantP.O. Box 10429Southport, NC 28461o: 910.457.3698 10 CFR 50.73NOV 1 62015Serial: BSEP 15-0084U.S. Nuclear Regulatory Commission ATTN: Document Control DeskWashington, DC 20555-0001
 
==Subject:==
 
Brunswick Steam Electric Plant, Unit Nos. 1 and 2Renewed Facility Operating License Nos. DPR-71 and DPR-62Docket Nos. 50-325 and 50-324Licensee Event Report 1-2015-002, Revision 1
 
==Reference:==
 
Licensee Event Report (LER) 1-2015-002 for Brunswick, Unit 1, "Emergency DieselGenerator Loss of Safety Function,"
Revision 0, Dated May 20, 2015, ADAMSAccession Number ML15149A148 In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Duke EnergyProgress, Inc., submits the enclosed Revision i to Licensee Event Report (LER) 1-2015-002.
This report provides results of the completed cause evaluation.
Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager -Regulatory
: Affairs, at (910) 457-2487.
Sincerely, William R. GideonSWR/swr
 
==Enclosure:==
 
Licensee Event Report 1-2015-002, Rev. 1 U.S. Nuclear Regulatory Commission Page 2 of 2cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region IIATTN: Regional Administrator 245 Peachtree Center Aye, NE, Suite 1200Atlanta, GA 30303-1257 U. S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River RoadSouthport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Mr. Andrew Hon (Mail Stop OWEN 8G9A) (Electronic Copy Only)11555 Rockville PikeRockville, MD 20852-2738 Chair -North Carolina Utilities Commission P.O. Box 29510Raleigh, NC 27626-0510 hIRC FORM 365 U.S. NUCLEAR REGULATORY COMMISSION
=APPROVED BY 0MB: NO. 3150-0104 EXPIRES:
01/31/2017
'02-2014) burden per response to comply with this mandatory collection request:
80 hours.
lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Intormation Collections LIE SEE EVENT REPORT 'LE R) Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by*° internet e-mail to Infocollects.Resource@nro.gov, and to the Desk Otficer, Office ot Intormation and(See Page 2 for required number of RegulatoryAffairs, NEOB-10202, (3150-0104),
Office of Management and Budget, Washington, DCdigits/characters for each block) 20503. It a means used to impose an information collection does not rdisplay a currently valid 0MBcontrol 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 NUMBER 13. PAGEBrunswick Steam Electric Plant (BSEP), Unit 1 05000325 1 OF 54. TITLEEmergency Diesel Generator Loss of Safety Function5. EVENT DATE 6. LER NUMBER I 7. REPORT DATE 8. OTHER FACILITIES INVOLVEDN. EUMERNT O.I E MONTH DAY YEAR BSEP Unit 2 05000324MONTH DAY YEAR YEAR SEUMENILRE FACLIYOAM FACILITY NAME DOCKET NUMBER03 21 2015 2015 -002 -01I 11 16 12015 050009. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
F] 50.73(a)(2)(vii) 1 E 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.,73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(C)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
: 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)1 0 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHEREl 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
[] 50.73(a)(2)(v)(D) specifyin Abstraot belowor in__________________
__________________________________________________________NR___FoNRCForm36A
: 12. LICENSEE CONTACT FOR THIS LER_ICENSEE CONTACT ITELEPHONE NUMBER (Include Ares Code)Lee Grzeck, Manager -Regulatory Affairs 1(910) 457-248713. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTMAU- REORA LE N- REOTALCAUSE SYSTEM COMPONENT FACTURER TO EPIX CAUSE SYSTEM COMPONENT FACTURER TO EPIXB EK 2 A160 No [14. SUPPLEMENTAL REPORT EXPECTED
: 15. EXPECTED MONTH IDAY YEARSUBMISSION
--El YES (If yes, complete
: 15. EXPECTED SUBMISSION DATE) []NO DATE5,BSTRACT (Limit to 1400 spaces, iLe., approximately 15 single-spaced typewritten lines)On April 23, 2015, following an engineering evaluation, it was determined that during a period of 12 minutesfrom 14:05 to 14:17 Eastern Daylight Time on March 21, 2015, emergency diesel generators (EDGs) 3 and 4could potentially have been unable to tie to their respective emergency busses. This was due to relays inbreaker control logic that were susceptible to electrical noise from nearby relays de-energizing that could haveprevented the output breakers from properly closing under certain conditions.
This is considered a loss ofsafety function of the onsite standby alternating current power source. Three of four EDGs are required tomitigate an accident on one unit while maintaining the other unit in a safe condition.
This condition is beingreported in accordance with 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.
The root cause of the event was a procedural inadequacy in the commercial grade dedication process thatallowed an unauthorized component modification to go unrecognized.
Affected circuits in all four EDGs havebeen modified.
The inadequate procedure has been revised, and site management and key personnel will bebriefed on lessons learned from the event.NRC FORM 366 (02-2014)
FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES:
01131/2017 02-2014) burden per response to comply mitth this mandatory collection request:
80 hours.= Reported lessons teamned are incorporated into the licensing process and fed back to industry.
* s 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°-- LICENSEE EVENT REPORT (LER) internet e-mail to Intocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affair, NEOB-10202, 3150-0104),
Office of Management and Budget,CONTINUATION SHEET Washington, DC 20503. It a means used to impose an information collection doss not displaysa currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is notrequired to respond to, the information collection.
: 1. FACILITY NAME [2. DOCKET 6. LER NUMBER J3. PAGEII -I SEQUENTIAL REVYEAR NUMBER NO.Brunswick Steam Electric Plant (BSEP) 05000325 YERj2 OF 5Unit 1 1J 2015 -002 -001NARRATIVE Energy Industry Identification System (EllS) codes are identified in the text as [XX].Background Initial Conditions At the time of the event, Unit 1 was in Mode 1 at approximately 100 percent of rated thermal power, andUnit 2 was in Mode 5 (i.e., Refueling).
The only Unit 1 safety-related equipment out of service at the time of this event was the 1 B ResidualHeat Removal System [BO] pump. This item of equipment being out of service had no effect on thesequence of events described in this report.Reportability CriteriaThis condition is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of a system that is needed to mitigate theconsequences of an accident.
The loss of safety function was discovered after the event had occurred; thus, no Event Notification (EN) was made to the NRC per the guidance of NUREG-1 022, "Event ReportGuidelines 10 CFR 50.72 and 50.73," Revision 3.Event Description During the Unit 2 refueling outage of spring 2015, emergency diesel generator 3 (EDG 3) [EK] reliability modifications were performed.
These modifications included replacement of the voltage regulator andgovernor.
The governor replacement was completed while EDG 3 was removed from service fromMarch 10, 2015, through March 18, 2015.During post-maintenance testing (PMT) for the governor replacement, the EDG 3 output breaker failed toremain closed in response to a simulated loss of offsite power condition.
This failure was determined tohave been caused by a relay, designated 2-DG3-RCR, which experienced oscillation in response toelectrical noise generated by a second relay de-energizing, designated 2-DG3-RCR-X.
Both relays werereplaced; additional monitoring equipment was installed, and the PMT for EDG 3 was successfully completed on March 18, 2015.Based on the failure of relay 2-DG3-RCR, a decision was made to proactively replace the identical relayson EDG 4, designated 2-DG4-RCR and 2-DG4-RCR-X.
On March 19, 2015, EDG 4 was removed fromservice, and during the ensuing maintenance window, the relays were replaced.
During the PMT onMarch 21, 2015, for EDG 4, the output breaker cycled four times before remaining closed. This resultedfrom misoperation of the newly installed relay, 2-DG4-RCR.
A failure of the EDG output breaker to close due to erratic RCR relay operation could occur only if theaffected EDG were already running and not tied to its electrical bus when a breaker closure signal isIINRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (o2-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME [2. DOCKET 6. LER NUMBER J 3. PAGEIII SEQUENTIAL REVBrnwikSea lcti lat(SE) IYEAR NUMBER NO.BunsicSteailcri ln (BP 05000325 j3 OF 5[Unit__1_
2015 -002 -001NARRATIVE received.
In this condition, it could not be assured that the EDG output breaker would remain closed. Assuch, the affected EDG would be considered inoperable.
When an affected EDG was in the standbymode, the RCR relay issue would have no effect, so the EDG remained operable and able to perform itssafety function.
On March 21, 2015, procedure 0MST-DG14R, "DG-4 Loading Test," was performed as part of the PMTfor EDG 4. This test starts all four EDGs. EDG 3 ran unloaded from 13:08 Eastern Daylight Time (EDT)until it was shut down at 14:38 EDT. During this 90-minute span, therefore, EDG 3 was inoperable.
Concurrently during 0MST-DG14R, EDG 4 was loaded, separated from the bus, and loaded again.During the time EDG 4 was running unloaded, it was also inoperable.
For the period of 14:05 EDT until14:17 EDT, both EDG 3 and EDG 4 were running and were unloaded.
Therefore, for this 12-minute period, both EDGs 3 and 4 were considered to be inoperable.
After the failure of EDG 4 to tie to its bus, bench testing closely matching field conditions showed thatrelay 2-DG4-RCR oscillated due to voltage transients generated when the adjacent RCR-X relay wasde-energized.
The bench testing also demonstrated that installing a transient voltage suppressor acrossthe RCR-X relay coil eliminated the erratic behavior of the RCR relay.The original relay 2-DG4-RCR was bench tested and found to be not susceptible to misoperation due toelectrical noise. It was then re-installed on March 22, 2015. In addition, given what was learned duringbench testing, engineers suspected that installation of test equipment on EDG 3 (i.e., data recorder andSimpson volt-ohmmeter) had had a similar effect as the transient voltage suppressor by absorbing theIvoltage transient produced by the RCR-X relay. A test was performed on EDG 3 to challenge the newRCR relay, and it showed oscillation in response to noise generated by the RCR-X relay. It was thenconcluded that the presence of test equipment had contributed to the successful PMT of EDG 3 onMarch 18, 2015. A modification to install a transient voltage suppressor across the RCR-X relay Coil onEDG 3 was developed.
The transient voltage suppressor modification to EDG 3 was installed andIsuccessfully tested on March 23, 2015.This condition resulted in a brief loss of safety function for the onsite standby alternating current (AC)power source. Three of four EDGs are required to mitigate an accident on one unit while maintaining theother unit in a safe condition.
With both EDGs 3 and 4 inoperable, only EDGs 1 and 2 were operable, andthe ability to perform this safety function was adversely affected.
The event is not reportable as acondition prohibited by the TS because in all cases, the diesels were returned to service in less than thetime allowed by the applicable required action statement.
Event CauseThe immediate, technical cause of the loss of safety function was that both EDG 3 and EDG 4 weresimultaneously in a condition where it could not be assured that their output breakers would close to theiremergency busses. EDG 3 was in a degraded condition after the initial relay replacement because newlyinstalled relay 2-DG3-RCR was susceptible to electrical noise generated by relay 2-DG3-RCR-X.
EDG 4was likewise in a degraded condition because relay 2-DG4-RCR was proactively
: replaced, and thereplacement relay was susceptible to electrical noise generated by relay 2-DG4-RCR-X.
The effect ofthe electrical noise upon the relay was to cause it to oscillate briefly when the nearby RCR-X relayactuated.
Contacts from the oscillating relay then affected the logic for closing and trip)ping the EDGoutput breaker, resulting in the breaker closing and immediately tripping.
Because of the location of theNRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEIISEQUENTIAL REVBrunswick Steam Electric Plant (BSEP) 05YER0NMBER NO.4  OUnit 1
* 5035 2015 -002 -001NARRATIVE contacts in the breaker logic, the oscillation could affect the logic only if the EDG were already runningand not tied to its bus. If the EDG were starting from standby, the relay problem would have no effectbecause the oscillation would settle out long before the EDG came up to speed where the breaker couldtie to its bus.Root cause investigators found that the manufacturer Of the RCR relays had introduced a complexprogrammable logic device (CPLD) into the design. The manufacturer retained the original part numberfor the relay, and did not notify BSEP that the design had been altered to include a CPLD. The change isnot visible externally because the timer circuit board containing the CPLD is enclosed within the relaybody, requiring disassembly to see it. When this condition was reported per 10 CFR 21, BSEP did notappear in the affected plants list because the relays had been obtained as commercial grade and laterdedicated for safety-related use. Therefore, industry operating experience published via the 10 CER 21process was not recognized as applicable to BSEP.The investigation also identified the fact that the decision to replace the RCR relay on EDG 4 was madewithout fully understanding the original fault with EDG 3 RCR relay.A root cause of the event was that procedure AD-EG-ALL-1 103, "Procurement Engineering Products,"
contained no guidance or requirement for the examination of dedicated high risk items that may besusceptible to a manufacturer introducing a CPLD or digital device in the item's circuitry.
Safety Assessment There was no actual safety consequence associated with this event, and the potential safetysignificance of this event is minimal.
As stated previously, EDG 3 and EDG 4 were susceptible to thisfailure mechanism only when susceptible relays were installed in the breaker logic for both diesels, andboth diesels were running and not tied to their electrical busses. The duration over which both dieselsand their breaker Logic met these conditions was a total of 12 minutes.Technical Specifications Bases 3.8.1, "AC Sources -Operating,"
states that the safety function of theelectrical power system is to provide sufficient
: capacity, capability, redundancy, and reliability to ensurethe availability of necessary power to engineered safety features (ESE) systems so that the fuel, ReactorCoolant System (RCS), and containment design limits are not exceeded.
Technical Specification 3.8.2,"AC Sources -Shutdown,"
states that the safety function of the AC sources is to ensure that the facilitycan be maintained in the shutdown or refueling condition for extended periods; sufficient instrumentation and control capability is available for monitoring and maintaining the unit status, and adequate ACelectrical power is provided to mitigate events postulated during shutdown, such as an inadvertent draindown of the vessel or a fuel handling accident.
The EDGs must provide power for these safetyfunctions should a loss of offsite power (LOOP) occur.In addition, the Updated Final Safety Analysis Report (UFSAR) states that three of the four EDGs mustbe available to mitigate a design basis accident on one unit and a shutdown of the other unit withoutoffsite power available.
Since only two diesels were available during the 12-minute duration of the event, reasonable assurance could not be established that the safety functions could be met on both the operating unit and theshutdown unit.NRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER j 3. PAGE05035SEQUENTIAL REVBrunswick Steam Electric Plant (BSEP) 05YEAR3NUMBEOFNO Uniti j1 2015 -002 -0011~ONARRATIVE Probabilistic Risk Analysis (PRA) examined the change in risk of having EDG 3 and EDG 4simultaneously out of service, conservatively assuming a full hour for the duration.
During the event,both EDG 1 and EDG 2 were available and protected, along with the supplemental diesel and offsiteelectrical sources.
The analysis showed the change in Core Damage Frequency (CDE) and Large EarlyRelease Frequency (LERE) was negligible.
Corrective ActionsAny changes to the corrective actions and schedules noted below will be made in accordance with thesite's corrective action program.To prevent recurrence of a similar event, procedure AD-EG-ALL-1 103, "Procurement Engineering Products,"
has been revised.The following actions have been completed to address the relay issue.* A transient voltage suppressor has been installed across the RCR-X relays in all four EDGs.* A review of circuits containing Allen-Bradley type 700-RTC relays has been performed, identifying specific areas where a relay of this type is located adjacent to a GE type HGA or HFArelay. Condition reports have been initiated for conditions requiring further engineering analysis.
In addition, site leadership and key personnel assigned to the Outage Control Center will be briefed onlessons learned from this event. This action is currently scheduled to be completed by March 1, 2016.Previous Similar EventsA review of LERs for the past three years did not identify any previous similar occurrences.
A review ofthe site's Corrective Action Program database also did not identify any previous similar occurrences.
Commitments No regulatory commitments are contained in this report.NRC FORM 366A (02-2014)
~(ENERGY William R. GideonVice President Brunswick Nuclear PlantP.O. Box 10429Southport, NC 28461o: 910.457.3698 10 CFR 50.73NOV 1 62015Serial: BSEP 15-0084U.S. Nuclear Regulatory Commission ATTN: Document Control DeskWashington, DC 20555-0001
 
==Subject:==
 
Brunswick Steam Electric Plant, Unit Nos. 1 and 2Renewed Facility Operating License Nos. DPR-71 and DPR-62Docket Nos. 50-325 and 50-324Licensee Event Report 1-2015-002, Revision 1
 
==Reference:==
 
Licensee Event Report (LER) 1-2015-002 for Brunswick, Unit 1, "Emergency DieselGenerator Loss of Safety Function,"
Revision 0, Dated May 20, 2015, ADAMSAccession Number ML15149A148 In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Duke EnergyProgress, Inc., submits the enclosed Revision i to Licensee Event Report (LER) 1-2015-002.
This report provides results of the completed cause evaluation.
Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager -Regulatory
: Affairs, at (910) 457-2487.
Sincerely, William R. GideonSWR/swr
 
==Enclosure:==
 
Licensee Event Report 1-2015-002, Rev. 1 U.S. Nuclear Regulatory Commission Page 2 of 2cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region IIATTN: Regional Administrator 245 Peachtree Center Aye, NE, Suite 1200Atlanta, GA 30303-1257 U. S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River RoadSouthport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Mr. Andrew Hon (Mail Stop OWEN 8G9A) (Electronic Copy Only)11555 Rockville PikeRockville, MD 20852-2738 Chair -North Carolina Utilities Commission P.O. Box 29510Raleigh, NC 27626-0510 hIRC FORM 365 U.S. NUCLEAR REGULATORY COMMISSION
=APPROVED BY 0MB: NO. 3150-0104 EXPIRES:
01/31/2017
'02-2014) burden per response to comply with this mandatory collection request:
80 hours.
lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Intormation Collections LIE SEE EVENT REPORT 'LE R) Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by*° internet e-mail to Infocollects.Resource@nro.gov, and to the Desk Otficer, Office ot Intormation and(See Page 2 for required number of RegulatoryAffairs, NEOB-10202, (3150-0104),
Office of Management and Budget, Washington, DCdigits/characters for each block) 20503. It a means used to impose an information collection does not rdisplay a currently valid 0MBcontrol 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 NUMBER 13. PAGEBrunswick Steam Electric Plant (BSEP), Unit 1 05000325 1 OF 54. TITLEEmergency Diesel Generator Loss of Safety Function5. EVENT DATE 6. LER NUMBER I 7. REPORT DATE 8. OTHER FACILITIES INVOLVEDN. EUMERNT O.I E MONTH DAY YEAR BSEP Unit 2 05000324MONTH DAY YEAR YEAR SEUMENILRE FACLIYOAM FACILITY NAME DOCKET NUMBER03 21 2015 2015 -002 -01I 11 16 12015 050009. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
F] 50.73(a)(2)(vii) 1 E 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.,73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(C)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
: 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)1 0 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHEREl 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
[] 50.73(a)(2)(v)(D) specifyin Abstraot belowor in__________________
__________________________________________________________NR___FoNRCForm36A
: 12. LICENSEE CONTACT FOR THIS LER_ICENSEE CONTACT ITELEPHONE NUMBER (Include Ares Code)Lee Grzeck, Manager -Regulatory Affairs 1(910) 457-248713. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTMAU- REORA LE N- REOTALCAUSE SYSTEM COMPONENT FACTURER TO EPIX CAUSE SYSTEM COMPONENT FACTURER TO EPIXB EK 2 A160 No [14. SUPPLEMENTAL REPORT EXPECTED
: 15. EXPECTED MONTH IDAY YEARSUBMISSION
--El YES (If yes, complete
: 15. EXPECTED SUBMISSION DATE) []NO DATE5,BSTRACT (Limit to 1400 spaces, iLe., approximately 15 single-spaced typewritten lines)On April 23, 2015, following an engineering evaluation, it was determined that during a period of 12 minutesfrom 14:05 to 14:17 Eastern Daylight Time on March 21, 2015, emergency diesel generators (EDGs) 3 and 4could potentially have been unable to tie to their respective emergency busses. This was due to relays inbreaker control logic that were susceptible to electrical noise from nearby relays de-energizing that could haveprevented the output breakers from properly closing under certain conditions.
This is considered a loss ofsafety function of the onsite standby alternating current power source. Three of four EDGs are required tomitigate an accident on one unit while maintaining the other unit in a safe condition.
This condition is beingreported in accordance with 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.
The root cause of the event was a procedural inadequacy in the commercial grade dedication process thatallowed an unauthorized component modification to go unrecognized.
Affected circuits in all four EDGs havebeen modified.
The inadequate procedure has been revised, and site management and key personnel will bebriefed on lessons learned from the event.NRC FORM 366 (02-2014)
FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES:
01131/2017 02-2014) burden per response to comply mitth this mandatory collection request:
80 hours.= Reported lessons teamned are incorporated into the licensing process and fed back to industry.
* s 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°-- LICENSEE EVENT REPORT (LER) internet e-mail to Intocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affair, NEOB-10202, 3150-0104),
Office of Management and Budget,CONTINUATION SHEET Washington, DC 20503. It a means used to impose an information collection doss not displaysa currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is notrequired to respond to, the information collection.
: 1. FACILITY NAME [2. DOCKET 6. LER NUMBER J3. PAGEII -I SEQUENTIAL REVYEAR NUMBER NO.Brunswick Steam Electric Plant (BSEP) 05000325 YERj2 OF 5Unit 1 1J 2015 -002 -001NARRATIVE Energy Industry Identification System (EllS) codes are identified in the text as [XX].Background Initial Conditions At the time of the event, Unit 1 was in Mode 1 at approximately 100 percent of rated thermal power, andUnit 2 was in Mode 5 (i.e., Refueling).
The only Unit 1 safety-related equipment out of service at the time of this event was the 1 B ResidualHeat Removal System [BO] pump. This item of equipment being out of service had no effect on thesequence of events described in this report.Reportability CriteriaThis condition is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of a system that is needed to mitigate theconsequences of an accident.
The loss of safety function was discovered after the event had occurred; thus, no Event Notification (EN) was made to the NRC per the guidance of NUREG-1 022, "Event ReportGuidelines 10 CFR 50.72 and 50.73," Revision 3.Event Description During the Unit 2 refueling outage of spring 2015, emergency diesel generator 3 (EDG 3) [EK] reliability modifications were performed.
These modifications included replacement of the voltage regulator andgovernor.
The governor replacement was completed while EDG 3 was removed from service fromMarch 10, 2015, through March 18, 2015.During post-maintenance testing (PMT) for the governor replacement, the EDG 3 output breaker failed toremain closed in response to a simulated loss of offsite power condition.
This failure was determined tohave been caused by a relay, designated 2-DG3-RCR, which experienced oscillation in response toelectrical noise generated by a second relay de-energizing, designated 2-DG3-RCR-X.
Both relays werereplaced; additional monitoring equipment was installed, and the PMT for EDG 3 was successfully completed on March 18, 2015.Based on the failure of relay 2-DG3-RCR, a decision was made to proactively replace the identical relayson EDG 4, designated 2-DG4-RCR and 2-DG4-RCR-X.
On March 19, 2015, EDG 4 was removed fromservice, and during the ensuing maintenance window, the relays were replaced.
During the PMT onMarch 21, 2015, for EDG 4, the output breaker cycled four times before remaining closed. This resultedfrom misoperation of the newly installed relay, 2-DG4-RCR.
A failure of the EDG output breaker to close due to erratic RCR relay operation could occur only if theaffected EDG were already running and not tied to its electrical bus when a breaker closure signal isIINRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (o2-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME [2. DOCKET 6. LER NUMBER J 3. PAGEIII SEQUENTIAL REVBrnwikSea lcti lat(SE) IYEAR NUMBER NO.BunsicSteailcri ln (BP 05000325 j3 OF 5[Unit__1_
2015 -002 -001NARRATIVE received.
In this condition, it could not be assured that the EDG output breaker would remain closed. Assuch, the affected EDG would be considered inoperable.
When an affected EDG was in the standbymode, the RCR relay issue would have no effect, so the EDG remained operable and able to perform itssafety function.
On March 21, 2015, procedure 0MST-DG14R, "DG-4 Loading Test," was performed as part of the PMTfor EDG 4. This test starts all four EDGs. EDG 3 ran unloaded from 13:08 Eastern Daylight Time (EDT)until it was shut down at 14:38 EDT. During this 90-minute span, therefore, EDG 3 was inoperable.
Concurrently during 0MST-DG14R, EDG 4 was loaded, separated from the bus, and loaded again.During the time EDG 4 was running unloaded, it was also inoperable.
For the period of 14:05 EDT until14:17 EDT, both EDG 3 and EDG 4 were running and were unloaded.
Therefore, for this 12-minute period, both EDGs 3 and 4 were considered to be inoperable.
After the failure of EDG 4 to tie to its bus, bench testing closely matching field conditions showed thatrelay 2-DG4-RCR oscillated due to voltage transients generated when the adjacent RCR-X relay wasde-energized.
The bench testing also demonstrated that installing a transient voltage suppressor acrossthe RCR-X relay coil eliminated the erratic behavior of the RCR relay.The original relay 2-DG4-RCR was bench tested and found to be not susceptible to misoperation due toelectrical noise. It was then re-installed on March 22, 2015. In addition, given what was learned duringbench testing, engineers suspected that installation of test equipment on EDG 3 (i.e., data recorder andSimpson volt-ohmmeter) had had a similar effect as the transient voltage suppressor by absorbing theIvoltage transient produced by the RCR-X relay. A test was performed on EDG 3 to challenge the newRCR relay, and it showed oscillation in response to noise generated by the RCR-X relay. It was thenconcluded that the presence of test equipment had contributed to the successful PMT of EDG 3 onMarch 18, 2015. A modification to install a transient voltage suppressor across the RCR-X relay Coil onEDG 3 was developed.
The transient voltage suppressor modification to EDG 3 was installed andIsuccessfully tested on March 23, 2015.This condition resulted in a brief loss of safety function for the onsite standby alternating current (AC)power source. Three of four EDGs are required to mitigate an accident on one unit while maintaining theother unit in a safe condition.
With both EDGs 3 and 4 inoperable, only EDGs 1 and 2 were operable, andthe ability to perform this safety function was adversely affected.
The event is not reportable as acondition prohibited by the TS because in all cases, the diesels were returned to service in less than thetime allowed by the applicable required action statement.
Event CauseThe immediate, technical cause of the loss of safety function was that both EDG 3 and EDG 4 weresimultaneously in a condition where it could not be assured that their output breakers would close to theiremergency busses. EDG 3 was in a degraded condition after the initial relay replacement because newlyinstalled relay 2-DG3-RCR was susceptible to electrical noise generated by relay 2-DG3-RCR-X.
EDG 4was likewise in a degraded condition because relay 2-DG4-RCR was proactively
: replaced, and thereplacement relay was susceptible to electrical noise generated by relay 2-DG4-RCR-X.
The effect ofthe electrical noise upon the relay was to cause it to oscillate briefly when the nearby RCR-X relayactuated.
Contacts from the oscillating relay then affected the logic for closing and trip)ping the EDGoutput breaker, resulting in the breaker closing and immediately tripping.
Because of the location of theNRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEIISEQUENTIAL REVBrunswick Steam Electric Plant (BSEP) 05YER0NMBER NO.4  OUnit 1
* 5035 2015 -002 -001NARRATIVE contacts in the breaker logic, the oscillation could affect the logic only if the EDG were already runningand not tied to its bus. If the EDG were starting from standby, the relay problem would have no effectbecause the oscillation would settle out long before the EDG came up to speed where the breaker couldtie to its bus.Root cause investigators found that the manufacturer Of the RCR relays had introduced a complexprogrammable logic device (CPLD) into the design. The manufacturer retained the original part numberfor the relay, and did not notify BSEP that the design had been altered to include a CPLD. The change isnot visible externally because the timer circuit board containing the CPLD is enclosed within the relaybody, requiring disassembly to see it. When this condition was reported per 10 CFR 21, BSEP did notappear in the affected plants list because the relays had been obtained as commercial grade and laterdedicated for safety-related use. Therefore, industry operating experience published via the 10 CER 21process was not recognized as applicable to BSEP.The investigation also identified the fact that the decision to replace the RCR relay on EDG 4 was madewithout fully understanding the original fault with EDG 3 RCR relay.A root cause of the event was that procedure AD-EG-ALL-1 103, "Procurement Engineering Products,"
contained no guidance or requirement for the examination of dedicated high risk items that may besusceptible to a manufacturer introducing a CPLD or digital device in the item's circuitry.
Safety Assessment There was no actual safety consequence associated with this event, and the potential safetysignificance of this event is minimal.
As stated previously, EDG 3 and EDG 4 were susceptible to thisfailure mechanism only when susceptible relays were installed in the breaker logic for both diesels, andboth diesels were running and not tied to their electrical busses. The duration over which both dieselsand their breaker Logic met these conditions was a total of 12 minutes.Technical Specifications Bases 3.8.1, "AC Sources -Operating,"
states that the safety function of theelectrical power system is to provide sufficient
: capacity, capability, redundancy, and reliability to ensurethe availability of necessary power to engineered safety features (ESE) systems so that the fuel, ReactorCoolant System (RCS), and containment design limits are not exceeded.
Technical Specification 3.8.2,"AC Sources -Shutdown,"
states that the safety function of the AC sources is to ensure that the facilitycan be maintained in the shutdown or refueling condition for extended periods; sufficient instrumentation and control capability is available for monitoring and maintaining the unit status, and adequate ACelectrical power is provided to mitigate events postulated during shutdown, such as an inadvertent draindown of the vessel or a fuel handling accident.
The EDGs must provide power for these safetyfunctions should a loss of offsite power (LOOP) occur.In addition, the Updated Final Safety Analysis Report (UFSAR) states that three of the four EDGs mustbe available to mitigate a design basis accident on one unit and a shutdown of the other unit withoutoffsite power available.
Since only two diesels were available during the 12-minute duration of the event, reasonable assurance could not be established that the safety functions could be met on both the operating unit and theshutdown unit.NRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014)
LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER j 3. PAGE05035SEQUENTIAL REVBrunswick Steam Electric Plant (BSEP) 05YEAR3NUMBEOFNO Uniti j1 2015 -002 -0011~ONARRATIVE Probabilistic Risk Analysis (PRA) examined the change in risk of having EDG 3 and EDG 4simultaneously out of service, conservatively assuming a full hour for the duration.
During the event,both EDG 1 and EDG 2 were available and protected, along with the supplemental diesel and offsiteelectrical sources.
The analysis showed the change in Core Damage Frequency (CDE) and Large EarlyRelease Frequency (LERE) was negligible.
Corrective ActionsAny changes to the corrective actions and schedules noted below will be made in accordance with thesite's corrective action program.To prevent recurrence of a similar event, procedure AD-EG-ALL-1 103, "Procurement Engineering Products,"
has been revised.The following actions have been completed to address the relay issue.* A transient voltage suppressor has been installed across the RCR-X relays in all four EDGs.* A review of circuits containing Allen-Bradley type 700-RTC relays has been performed, identifying specific areas where a relay of this type is located adjacent to a GE type HGA or HFArelay. Condition reports have been initiated for conditions requiring further engineering analysis.
In addition, site leadership and key personnel assigned to the Outage Control Center will be briefed onlessons learned from this event. This action is currently scheduled to be completed by March 1, 2016.Previous Similar EventsA review of LERs for the past three years did not identify any previous similar occurrences.
A review ofthe site's Corrective Action Program database also did not identify any previous similar occurrences.
Commitments No regulatory commitments are contained in this report.NRC FORM 366A (02-2014)}}

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