05000461/LER-2009-001, Regarding Safety Function Lost Due to Capacitor Failure on Circuit Card
| ML092520352 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 08/28/2009 |
| From: | Kearney F Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SRRS 5A.108, U-603912 LER 09-001-00 | |
| Download: ML092520352 (5) | |
| 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)(ii)(A), Seriously Degraded 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)(iii) 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4612009001R00 - NRC Website | |
text
Exelon.
Nuclear Clinton Power Station 8401 Power Road Clinton, IL 61727-9351 U-603912 August 28, 2009 10 CFR 50.73 SRRS 5A.108 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2009-001-00 Enclosed is Licensee Event Report (LER) No. 2009-001-00: Safety Function Lost Due to Capacitor Failure on Circuit Card. This report is being submitted in accordance with the requirements of 10 CFR 50.73 There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact Mr. D. A. Tran, at (217)-937-4068.
FA. KearrYeg 0-Site Vice President Clinton Power Station RSF/blf
Enclosures:
Licensee Event Report 2009-001 -00 cc:
Regional Administrator-NRC Region III NRC Senior Resident Inspector - Clinton Power Station Director, Division of Nuclear Security, Office of Nuclear Security and Incident Response Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
i3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 4
- 4. TITLE Safety Function Lost Due to Capacitor Failure on Circuit Card
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I SEQUEARIA L
R I
FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR None 05000 FACILITY NAME DOCKET NUMBER 07 02 09 2009 001-00 08 28 09 None 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[l 50.73(a)(2)(vii)
El 20.2201(d)
[1 20.2203(a)(3)(ii)
[1 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)
E] 20.2203(a)(2)(i)
[I 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)
[E 20.2203(a)(2)(iii)
El 50.36(c)(2)
[3 50.73(a)(2)(v)(A)
El 73.71(a)(4) 97 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[E 50.73(a)(2)(v)(C)
[E OTHER [E 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
[
50.73(a)(2)(v)(D)
Specify in Abstract below or in At about 1608 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.11844e-4 months <br />, the Division 3 logic circuit card was removed for further site testing (using a GENRAD tester). During this site testing, the POI circuitry of the Division 3 HPCS logic circuit card failed the test.
Subsequently, the Division 3 logic circuit card was sent to the supplier for further troubleshooting and diagnostic testing. Supplier investigation of the Division 3 logic circuit card confirmed the card failure was due to degraded coupling ceramic capacitors [CAP] in the POI circuitry. The card was repaired by the supplier and returned to the station.
At 1350 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.13675e-4 months <br /> on 7/7/09, following completion of installation of the card, post-maintenance testing and restoration of the automatic functions of the card, HPCS, and Division 3 DG and SX were declared operable.
No other inoperable equipment or components directly affected this event.
CAUSE OF EVENT
The cause of the Division 3 logic circuit card failure is attributed to a knit-line delamination and associated cracks that caused a low insulation resistance of the ceramic capacitor in the POI circuit of the card that was installed in 1987. The ceramic capacitor is one of two coupling capacitors in series with a resistor to form a time delay that prevents erroneous signals from actuating field devices during circuit card power-up.
The purpose of the POI circuit is to set latches to a predetermined state during power-up or during a circuit card removal, and to inhibit the outputs to the field instrumentation during power-up to allow logic setting time. The circuit analysis determined that one degraded ceramic capacitor on the POI circuit caused the HPCS-1 circuit card to malfunction, blocking initiation signals for HPCS, Division 3 DG and Division 3 SX systems. The vendor failure analysis of the capacitor was unable to identify the cause of the knit-line delamination and cracks; however, further industry research shows the most probable cause of the defective capacitor is a manufacturing anomaly that limited the expected life of the capacitor.
SAFETY ANALYSIS
This event is reportable under the provisions of 10 CFR 50.73(a)(2)(v)(D) due to a condition that could have prevented fulfillment of the HPCS safety function to mitigate the consequences of an accident.
The HPCS and Division 3 DG and Division 3 SX systems were inoperable but available from 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on 7/2/09 until declaration of operable status at 1350 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.13675e-4 months <br /> on 7/7/09, except for a period of 71 minutes from 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> to 1311 hours0.0152 days <br />0.364 hours <br />0.00217 weeks <br />4.988355e-4 months <br /> on 7/7/09. During this time, the HPCS and Division 3 DG and Division 3 SX systems were inoperable and unavailable while control power fuses for the HPCS pump were removed for installation of the repaired Division 3 logic circuit card.
During the times the HPCS and Division 3 DG and Division 3 SX systems were available, the manual start capability of the HPCS pump and the functions for opening the injection valve using hand switches in the main control room continued to be available for operator manual initiation if required. Additionally, the manual initiation functions for the Division 3 DG and SX systems were available in the main control room if required during this time.
The RCIC system was operable during this event. Although no credit is taken in the safety analysis for the RCIC System, it performs a similar function as HPCS but has reduced makeup capability. Nevertheless, it will maintain inventory and cool the core, while the Reactor Coolant System is still pressurized, following a reactor pressure vessel isolation. If HPCS fails to maintain reactor water level above Level 1, it is backed up by automatic initiation
of Automatic Depressurization System in combination with Low Pressure Coolant Injection [80] and Low Pressure Core Spray [BM] systems; these systems remained operable during this event.
CORRECTIVE ACTION
The Division 3 logic circuit card that failed has been repaired and a spare Division 3 logic circuit card will be obtained.
A Performance Centered Maintenance template will be created and strategies for performing preventive maintenance activities will be evaluated for NSPS circuit cards.
PREVIOUS OCCURRENCES
The 7/2/09 event was a repeat failure of STS identified on 6/24/09 (in issue report 934532) that caused the STS system to stop testing. The STS 6/24/09 failure was an intermittent failure on the HPCS-1 circuit card that was reset and ran successfully in fully automatic test mode. This event was not reportable under the provisions of 10 CFR 50.73.
COMPONENT FAILURE DATA
Circuit Card Manufacturer: General Electric Nomenclature: HPCS-1 circuit card Manufacture Model Number: 147D8500G001 Part Number: 1PAP663BA16A114 Ceramic Capacitor Manufacturer: KEMET Electronic Corporation Nomenclature: Multi-Layer Ceramic Capacitor, one micro-Farad Manufacturer Model Number: 1CK06BX105KPRINTED ON RECYCLED PAPER NRIC FORM 366A (9-2007)
PRINTED ON RECYCLED PAPER