ML14155A075

LER 14-002-00 for Seabrook Station Regarding Reactor Coolant Pump Undervoltage Time Delay Relays Exceed Acceptance Criteria

ML14155A075
Person / Time
Site:	Seabrook
Issue date:	06/02/2014
From:	Ossing M H NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-14098 LER 14-002-00
Download: ML14155A075 (4)

Text

NEXTeraENERGIY.ýJune 2, 201410 CFR 50.73Docket No.50-443SBK-L-14098U. S. Nuclear Regulatory CommissionAttn: Document Control DeskWashington, DC 20555-0001Seabrook StationLicensee Event Report (LER) 2014-002Reactor Coolant Pump Undervoltage Time Delay Relays Exceed AcceptanceEnclosed is Licensee Event Report (LER).2014-002. This LER reports a condition thatwas discovered at Seabrook Station on April 6, 2014. This event is being reportedpursuant to the requirements.of 10 CFR 50.73(a)(2)(i)(B), 50.73(a)(2)(v)(A) and50.73(a)(2)(vii).Should you require further information regarding this matter, please contact me at(603) 773-7512.Sincerely,NextEra Energy Seabrook, LLCMidhael'tI. 6ssingJLicensing Managýtcc: W. Dean, NRC Region I AdministratorJ. G. Lamb, NRC Project ManagerP. Cataldo, NRC Senior Resident InspectorNextEra Energy Seabrook, LLC.626 Lafayette Rd, Seabrook, NH 03874 SIRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 011311201702-2014)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 />.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..... LEEBranch (T-5 F53), U.S. Nuclear Regulatory Commission. Washington, DC 20555-0001, or byLICENSEE EVENT REPORTi (LER internet e-mail to Infocollects.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, DCfor each block) 20503. If a means used to impose an information collection does not display a currently valid OMBdigits/characters fcontrol 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 3. PAGESeabrook Station 05000443 1 OF4. TITLEReactor Coolant Pump Undervoltage Time Delay Relays Exceed Acceptance Criteria5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVEDMONTH DAY YEARi YER SQ NILRV MNH DY YA FACILIT NAME DOCKET NUMBERYER SEQUENTIAL REV MONTH DAY YEARNUMBER NO. 05000FACILITY NAME DOCKET NUMBER-2014 002 00 06 02 2014 ooo9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)[1 20.2201(b) El 20.2203(a)(3)(i) El 50.73(a)(2)(i)(C) ED 50.73(a)(2)(vii)6l 20.2201(d) L] 20.2203(a)(3)(ii) [] 50,73(a)(2)(ii)(A) El 50.73(a)(2)(viii)(A)[I 20.2203(a)(1) Li 20.2203(a)(4) El 50,73(a)(2)(ii)(B) Li 50.73(a)(2)(viii)(B)El 20.2203(a)(2)(i) LI 50.36(c)(1)(i)(A) Fi 50,73(a)(2)(iii) El 50.73(a)(2)(ix)(A)10. POWER LEVEL Li 20.2203(a)(2)(ii) Li 50.36(c)(1)(ii)(A) El 50.73(a)(2)(iv)(A) El 50.73(a)(2)(x)Li 20.2203(a)(2)(iii) EL 50.36(c)(2) 50.73(a)(2)(v)(A) [] 73.71(a)(4)0l 20.2203(a)(2)(iv) El 50.46(a)(3)(ii) F1 50.73(a)(2)(v)(B) [I 73.71(a)(5)000El 20.2203(a)(2)(v) Li 50.73(a)(2)(i)(A) Li 50.73(a)(2)(v)(C) Li OTHERLi 20.2203(a)(2)(vi) [ 50.73(a)(2)(i)(B) [] 50.73(a)(2)(v)(D) Specify in Abstract below or in_ NRC Form 366A12. LICENSEE CONTACT FOR THIS LER_ICENSEE CONTACT TELEPHONE NUMBER (include Area Code).Michael Ossing, Licensing Manager, 603-773-751213. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTCASE I M CI MANU- REPORTABLE MAU CAUOSEABYECATUE SYSTEM COMPONENT FACTURER TOEPIX CYO FACTURER TOEPIX14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEARSUBMISSIONYES (Ifyes, complete 15. EXPECTED SUBMISSION DATE) Li NO DATE 6 30 2014,BSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)On April 6, 2014, while the plant was in refueling outage sixteen, it was determined during surveillance testing that threeof four reactor coolant pump (RCP) undervoltage (UV) reactor trip channels exceeded the Technical Specification (TS)channel response time acceptance criteria of 1.5 seconds for the RCP UV reactor trip function. The condition for theRCP UV time delay relays exceeding tolerance was experienced on all four channels; however, only three of the fourchannels did not meet their TS required response times. Since this condition involved multiple similar components,there is evidence indicating that this condition may have arisen over time and three channels of RCP UV wereinoperable concurrently. This resulted in the plant operating in a condition prohibited by the TS.A root cause evaluation team has been formed but has not yet completed its evaluation to determine the cause of theexceedances. This LER will be supplemented with cause and corrective actions when determined. Corrective actionsalready taken include the replacement of one relay and adjustment of all relays to acceptable response times.NRC FORM 366 (02-2014)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017(02-2014)( 21 ..... , Estimated burden per response to comply with this mandatory cotlection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reportedlessons learned are incorporated into the licensing process and fed back to industry. Send commentsregarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S.Nuclear Regulatory .Commission, Washington, DC. 20555-0001, or by internet e-mail to-" LICENSEE EVENT REPORT (LER) .lnfocollects.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 20503. If a means usedCONTINUATION SHEET to impose an information collection does not display a currently valid OMB control number, the NRC maynot conduct or sponsor, and a person is not required to respond to, the information collection.1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGESEQUENTIAL REVYER UMBER NO.Seabrook Station 05000443 2 OF 32014 002 -00NARRATIVEDescription of EventOn April 6, 2014, while the plant was in refueling outage sixteen (OR 16), it was determined during surveillance testing thatthree of four reactor coolant pump (RCP) [AB, P] undervoltage (UV) reactor trip channels exceeded the TechnicalSpecification (TS) channel response time acceptance criteria of 1.5 seconds for the RCP UV reactor trip function. Thechannel response time was exceeded because the RCP UV time delay relays (62V) [AB 27 ] exceeded their maximumallowable response time. The condition for the RCP UV time delay relays exceeding tolerance was experienced on all fourchannels; however, only three of the four channels did not meet their TS required response times. Since this conditioninvolved multiple similar components, there is evidence indicating that this condition may have arisen over time and threechannels of ROP UV were inoperable. This resulted in the plant operating in a condition prohibited by the TS fromSeptember 20, 2012 (last calibration date for 1-RC-P-1-C relay) to April 1, 2014.Cause of EventThe cause of the event is currently being evaluated. This LER will be supplemented when the cause and correctiveactions are determined.Analysis of the EventAn out of tolerance condition was experienced on all four RCP 62V relays during OR16. The out of tolerance conditionwas identified during surveillance testing and resulted in three of four RCP UV trip channels exceeding their allowableresponse time.Surveillance requirement (SR) 4.3.1.2 requires verification of the response time of each reactor trip function listed in TSTable 3.3-1, Reactor Trip System Instrumentation, every 18 months. The response time for the RCP UV reactor tripchannel is -1.5 seconds. During the 18 month surveillance testing of the RCP 62V relays, three of the four RCP UVrelays exceeded their maximum allowable response time, resulting in the undervoltage reactor trip channels exceeding thelimit of -< 1.5 seconds.TS 3.3.1, Reactor Trip System Instrumentation, requires four channels of RCP UV instrumentation in Mode 1 and providesan action for the case that one RCP channel is inoperable. For this condition, however, three channels of RCP UV wereinoperable due to failure to meet the time response requirement of SR 4.3.1.2. Because no action addresses more thanone channel inoperable, TS 3.0.3, which requires a timely plant shutdown, would be applicable to this condition. Plantoperation with three RCP UV channels inoperable exceeded the shutdown times specified in TS 3.0.3; therefore, thecondition resulted in an operation or condition prohibited by the TS. This condition existed from the time the relays werelast calibrated in refueling outage fifteen (September 20, 2012) until the plant entered refueling outage sixteen (April 1,2014).This condition is being reported as a Safety System Functional Failure under 10 CFR 50.73(a)(2)(v)(A) as thecondition involved the failure of a reactor trip function credited for shutdown of the reactor and mitigation ofconsequences of an accident.This condition is also being reported under 10 CFR 50.73(a)(2)(vii)(A) as it involved the failure of an RCP UV reactortrip function credited for shutdown of the reactor and mitigation of consequences of an accident and caused multiplechannels to become inoperable. During OR16 surveillance testing, all four RCP UV time delay relays exceeded theirresponse time acceptance criteria. As a result three of the four channels exceeded their TS Channel response timefor the RCP UV trip function.NRC FORM 366A (02-2014)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 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 />. Reportedlessons learned are incorporated into the licensing process and fed back to industry. Send commentsregarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S.W1 Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail toLICENSEE EVENT REPORT (LER) lnfocollects.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 20503. If a means usedCONTINUATION SHEET to impose an information collection does not display a currently valid OMB control number, the NRC maynot conduct or sponsor, and a person is not required to respond to, the information collection.1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEYER SEQUENTIAL REVSeabrook Station 05000443 [ 3 OF 32014 -002 -00NARRATIVEAlthough determined to be a Safety System Functional Failure, the millisecond delays in reactor trip signal on RCP UV is notrisk significant because the RCP UV trip signal is one of several redundant and diverse reactor trip signals in the reactorprotection system. The RCP UV trip, along with the RCP underfrequency trip, serve as a backup to the low reactor coolantsystem (RCS) [AB] flow trip, which provides protection for a partial loss of RCS flow. The three trips also provide protectionfor a complete loss of RCS flow. The observed behavior in each UV trip circuit included a slight extension (0.0067, 0.0289and 0.1165 second) in the total circuit actuation time, not a failure of the circuit to actuate. Although the actuation timeexceeded the TS response time limit, the additional actuation time is very small and would have negligible impact on plantrisk. In addition, the RCP underfrequency trip, the RCS low flow trip, and manual trip provided redundant reactor tripcapability during this event. The Station intends to not count this event as an SSFF in the 2nd Quarter 2014 indicator as thecondition would not have caused the reactor to fail to trip.Corrective ActionsThe following corrective actions were completed1-RC-P-1-B undervoltage relay was replaced with a new relay and adjusted to the required response time.1-RC-P-1-C and 1-RC-P-1-D undervoltage relays were adjusted to the required response times.Similar EventsLER 2012-001 and 2012-002 reported inadequate testing of response times. The reports documented that surveillancetesting had not verified the response time of emergency feedwater relays (LER 2012-001) and reactor trip breaker shunttrip circuits (LER 2012-002). 'These events resulted from ineffective methods utilized in the mid 1980's to verify thatsurveillance test procedures ensured compliance with the TS.Additional InformationThe Energy Industry Identification System (EIIS) codes are included in this LER in the following format: [EIIS systemidentifier, ElIS component identifier].NRC FORM 366A (02-2014)