05000364/LER-1917-005, Regarding Power Range Nuclear Instrument Inoperable Due to Poor Connection of High Voltage Cable Connector
| ML18011A702 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 01/11/2018 |
| From: | Madison D Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-18-0024 LER 17-005-00 | |
| Download: ML18011A702 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2) 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 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(i) |
| 3641917005R00 - NRC Website | |
text
A Southern Nuclear January 11, 2018 Docket No.:
50-364 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant-Unit 2 Licensee Event Report 2017-005-00 bqlb M Fmey Nade:lr Plm!
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Thly95 Cclamhia. Al:lh:mD l6319 334 8J.USII 1d 334 8J.U57S lias NL-18-0024 Power Range Nuclear Instrument Inoperable Due to Poor Connection of Hiah Voltage Csble Connector Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Company is submitting the enclosed Licensee Event Report for Unit 2.
This letter contains no NRC commitments. If you have any questions regarding this submittal, please contact Mandy Ludlam at (334) 8144930.
Respectfully submitted, D.R. Madison VICe President - Farley DRM/rgs/cbg Enclosure: Unit 2 Licensee Event Report 2017-005-00 Cc: Regional Administrator, Region II NRR Project Manager-Farley Senior Resident Inspector-Farley RTYPE: CFA04.054
Joseph M. Farley Nuclear Plant-Unit 2 Ucensee Event Report 2017-005-00 Power Range Nuclear Instrument Inoperable Due to Poor Connection of High Voltage cable Connector Enclosure Unit 2 Ucensee Event Report 2017-005-00
NRC FORII361
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- 1. FACWTY NAME
- 2. DOCKET NUMBER 3.PAGE Joseph M. Farley Nuclear Plant. Unit 2 05000 364 I OF J
4.11TLE Power Range Nuclear Instrument Inoperable Due to Poor Connection of High Voltage Cable Connector
- 5. EVENT DATE DAY YEAR II 13 2017
- 9. OPERAnNG MODE 2
- 10. POWER LEVEL 002 LICENSEE CONTACT I.LERNUMBER YEAR ~~~
REV NO.
2017
- 005 00
- 7. REPORT DATE B. OTHER FActUTIES INVOLVED FACIUIY HAlE 01 11 2018 FloCIUTY HAlE
- 11. THIS REPORT IS SUBMmED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Chedr.II that 11PPM 0 20.2201(b) 0 202203(a)(3)(1)
D 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 0 20.2201(d)
D 20.2203(a)(3)(8) 0 50.73(a)(2)(ii){B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(&)(4) 0 50.73(a)(2)(lli)
D 50.73(a)(2)(1x)(A) 0 20.2203(a)(2)(i)
D 50.36{c:)(1)(i)(A) 0 50.73(a)(2)(1v)(A) 0 50.73(a)(2)(x) 0 20.2203(a)(2)(ii) 0 50.36{c:)(1)(ii)(A)
D 50.73(a)(2)(v)(A) 0 73.71(a)(4)
D 20.2203(a)(2)(iii) 0 50.36{c)(2) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(C) 0 73.n(a)(1)
D 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(D) 0 73.n(a)(2)(1) 0 20.2203(a)(2)(vl) 0 50.73(a)(2)(1)(8)
D 50.73(a)(2)(vll)
D 73.n(a)(2)(D) 0 50.73(a)(2)(i)(C) 0 OTHER Spedfy In Abolr.lct below or In NRC Fami311A
- 12. LICENSEE CONTACT FOR THIS LER Gene Surber, Licensing Supervisor TELEPHONE NUMBER (/rlelui>> AIN Code/
(334) 814-5448
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM MANU-REPORTABLE FACTURER TO EPDC COMPONENT A
- 14. SUPPLEMENTAL REPORT EXPECTED 0 YES (ffyes, complete 15. EXPECTED SUBMISSION DATE) 0 NO ABSTRACT (L/IIIIt to 1400 spaces. Le. apptOidmalely 15 sing/fHpac8d typewntten fino~
CAUSE
SYSTEM COW'ONEHT
- 15. EXPECTED SUBMISSION DATE MANU.
FACTURER MONTH DAY REPORTABLE TOEPIX During a reactor startup on November 13, 2017 at 0136, while at approximately 1.5% power (MODE 2), an.Ex core Power Range Nuclear Instrument (N-42) was declared inoperable due to lower than expected detector amps and indicated power. N-42 was reading approximately 0.4% lower power than the other three Power Range instruments. The malfunction was detennined to be the result of a failed High Voltage (HV) cable center pin connector to N-42. The HV cable connector was instaUed during N-42 rescaling on November 10,2017 in preparation for startup physics testing. N-42 provides an input signal to Cbaoocl2 of the Over Temperature Delta Temperature (OTDl) Reactor Trip Signal. Prior to the discovery-of the N-42 failure, Channel 3 of OTDT had also been declared inoperable and associated bistables tripped due to a failed Pressurizer Pressure transmitter. Therefore, it was determined that two cboooels of OTDT were inoperable longer than aUowcd by T echoical Specification (TS) 3.0.3. This condition is reportable per 10CFR50.73(a)(2Xi){B).
The HV cable connector was repaired and all channels were OPERABLE on November 14, 2017 at 1000. The installation of the HV cable connector with the faulty center pin was attributed to human error. Corrective actions include procedure changes, training, and departmental communications related to maintenance fundamentals.
NRC FORM 3611 (04-2017)
NRC FORII 366A (111.2011)
U.S. NUCt.EAR REGULA lORY COIIIIISSION APPROVED BY OMB: NO. 3160-0'104 UCENSEE EVENT REPORT (LER)
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- 1. FACIUTY NAME
- 2. OOCKET NUMBER s.
'Joseph M. Farley Nuclear Plant. Unit 2 IB-1-==1-0 NARRATJVE
EVENT DESCRIPTION
During reactor startup on November 13,2017 at 0136, while at approximately 1.5% power (MODE 2), an Excore Power Range Nuclear Instrument (N-42) [EIIS:IG] was declared inoperable due to lower than expected detector amps and indicated power. N-42 was reading approximately 0.4% lower power than the other three Power Range instruments. The malfunction was determined to be the result of a failed tf'IQh Voltage (HV) cable center pin connector to N-42. The HV cable connector was installed during N-42 rescaling on November 1 0, 2017 in preparation for startup physics testing and entry into MODE 2. Entry into MODE 2 occurred on November 12, 2017 at 1138. Technical Specification (TS) 3.3.1, Function 6, requires three operable channels of Over Temperature Delta Temperature (OTDT) during MODES 1 and 2.
N-42 provides an input signal to Channel 2 of the OTDT Reactor Trip Signal [EIIS:JC], while N-41 (Channel1) and N-43 (Channel 3) supply the remaining input signals. On November 11, 2017 at 0522 (prior to MODE 2 entry), Channel3 of OTDT had also been declared inoperable due to a failed Pressurizer Pressure Transmitter (PT -451) [EIIS:PIT]. The N-42 failure was identified and declared inoperable as Power Range Nuclear Instruments came on scale on November 13, 2011 at 0136 followirJQ completion of startup physics testing. This condition existed unbl Channel 3 of OTDT was restored on November 13, 2017 at 0115. Therefore, it was determined that when MODE 2 was entered, N-42 was inoperable and that two channels of OTDT were Inoperable longer than allowed by TS 3.0.3. This condition is reportable per 10CFR50. 73(a)(2)(i)(B).
EVENT CAUSAL ANALYSIS:
The N-42 instrument failure was caused by a bent center oonductor that prevented the instrument from making full oontact with the N-42 circuit and providing HV power to the instrument To rescale N-42, the HV oonnectors on the back of the drawer are disconnected such that the instrument is isolated. During this evolution the center pin on one of the oonnectors became bent or damaged during reinstallation by the Maintenance journeyman. These HV cable oonnectors are assembled in place and are not prefabricated. Due to repetitive removal and installation of these connectors over a cycle, it is not uncommon for one to fail or become damaged. Since there is no design test circuit, this condition was not detectable until neutron flux increased to a point where the detectors displayed actual values.
This event was classified as a Maintenance fundamental failure due to the HV power supply canter pin being either damaged before or during installation. Verifying the proper alignment and ensuring that the connectors are not damaged prior to installation is a fundamental part of manipulatirJQ electrical connections on plant equipment.
NRC FORM 3II8A (o.t-2017)
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- 1. FACIUTY NAIIE
- 2. DOCKET NUMBER
~Joseph M. Farley Nuclear Plant, Unit 2 18-1-==1-0
NARRATIVE
REPORT ABILITY AND SAFETY ASSESSMENT:
N-42 is part of the Nuclear lnsbumentation System (NIS) which consists of two Source Range instrwnents {N-31, N-32),
two Intermediate Range insbuments (N-35, N-36), and four Power Range instruments {N-41, N-42, N-43, N-44). Per TS 3.3.1, Reactor Trip System (RTS) lnsbumentation, three channels of OTOT are required in MODES 1 and 2. OTDT consists of three channels fed by N-41, N-42, and N-43 respectively. Thus, Farley unknowingly operated in a condition prohibited by TS as a result of two channels (Channel 2 and Channel 3) of OTDT being inoperable upon entry into MODE
- 2. This condition is reportable per 10CFR50.73(a)(2)(i)(B).
The OTDT trip function is provided in a 2 out of 3 trip logic to ensure that the design departure from nucleate boiling ratio (DNBR) is mel During this event Channel1 of OTDT was fully OPERABLE. Prior to entering MODE 2 the bistables for PT -457 (Channel 3 of OTDT) had been tripped by placing the channel in "Test* which is considered an actuated condition.
Even though Channel2 of OTOT was inoperable, the safety function was met with Channel1 fuDy OPERABLE and with Channel 3 blstables tripped. Adcfrtionally, the design of the Intermediate Range instruments (2 channels) provide redundant protection to the low setpoint of the Power Range instruments. Therefore, this is not reportable as a loss of safety function under 10CFR50.73(a)(2)(v).
CORRECTIVE ACTIONS
N-42 HV cable connector was repaired on November 14,2017.
Revise rescaling procedures for disconnecting and reconnecting signal cables to reinforce the need to take care of the center conductor to preclude damage; include required Inspections be performed after removal and prior to reinstallation; and to require caution during reinstallation to ensure connectors thread on smoothly and are fully engaged in the jack.
Communicate lessons learned through the Maintenance organization.
Training related to electrical connection fundamentals to be included in initial and continuing Maintenance training.
PREVIOUS OCCURENCES
No similar events were Identified.
OTHER SYSTEMS AFFECTED:
All systems affected were listed by EllS codes.
NRC FORM 3l5liA (04-2017)
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