ML071280276
| ML071280276 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Watts Bar, Sequoyah  |
| Issue date: | 05/04/2007 |
| From: | Wetzel B Tennessee Valley Authority |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| GL-07-001 | |
| Download: ML071280276 (14) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402-2801 May 4, 2007 10 CFR 50.54(f) 10 CFR 50.65 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-259 50-260 Tennessee Valley Authority
)
50-296 50-327 50-328 50-390 BROWNS FERRY NUCLEAR PLANT (BFN) UNITS 1, 2 AND 3, SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2, AND WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 - NUCLEAR REGULATORY COMMISSION (NRC) GENERIC LETTER (GL) 2007-01: INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS - 90 DAY RESPONSE This letter with enclosure provides TVA's 90-day response to GL 2007-01, "Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients," dated February 7, 2007. This information is provided pursuant to 10 CFR 50.54(f). There are no new regulatory commitments made by this letter.
Please direct any questions to Kent Brown at (423) 751-8227.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the I day of 2007.
Sincerely, Beth A. Wetzel Manager, Corporate Nuclear Licensing and Industry Affairs Enclosure cc: See page 2 Printed on recycled paper
U.S. Nuclear Regulatory Commission Page 2 May 4, 2007 Enclosure cc (Enclosure):
Brendan T. Moroney, Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North MS 08G9A 11555 Rockville Pike Rockville, Maryland 20852-2738 Margaret H. Chernoff, Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North MS 08G9A 11555 Rockville Pike Rockville, Maryland 20852-2738 Eva A. Brown, Senior Project Manager U.S. Nuclear Regulatory Commission MS 08G9A One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303-8931 NRC Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970 NRC Senior Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379-3624 NRC Senior Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381-2000
ENCLOSURE GENERIC LETTER (GL) 2007-01: INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS - 90 DAY RESPONSE REQUESTED INFORMATION (1)
Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicate the type, manufacturer, date of failure, type of service, voltage classes, years of service, and the root causes for the failure.
TVA Nuclear (TVAN) conducted a review of its Corrective Action database, Maintenance Rule database, and maintenance work order records to identify failures of underground/inaccessible AC power cables within the scope of 10 CFR 50.65 at Browns Ferry, Sequoyah and Watts Bar Nuclear Plants. The results of TVA's review are shown in the attached tables that identify both in-service and test failures at TVAN sites. It is worth noting that this data compilation represents our best effort in that early (historical) cable failure data was not recorded in a manner conducive to identifying specific causes of the failure. However, it is logical to assume that early failures were most likely attributable to manufacturing defects, installation damage, etc., rather than from moisture-induced, age-related degradation.
(2)
Describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables that support EDGs, offsite power, ESW, service water, component cooling water and other systems that were within the scope of 10 CFR 50.65 (Maintenance Rule).
The TVAN Cable Condition Monitoring Program (CCMP) is controlled under General Engineering Specification G-38, Installation, Modification and Maintenance of Insulated Cables Rated Up to 15,000 Volts. The TVAN CCMP is consistent with industry practices and recommendations as provided in the Nuclear Energy Institute (NEI) Medium Voltage Underground Cable White Paper (NEI 06-05, ADAMS ML061220137). The program consists of two complementary tests, both performed with a very low frequency (VLF), 0.1 Hertz, power supply. The first test is an age condition assessment technique known as "tan delta," "loss angle" or "dissipation factor." While preferably used as part of a trending program, one-shot readings are also used to predict remaining life or prioritize cable replacement. When the insulation is sound (i.e.;
no water trees, voids or moisture), a cable is essentially a long capacitor. In the ideal capacitor, current and voltage are 90 degrees out of phase. If wet service-aged cable contains water trees, voids and moisture, the resistive component of electrical current through the insulation increases. Thus, the dielectric no longer mimics the ideal capacitor and the resultant phase shift will be something less than 90 degrees. How much the dielectric departs from the ideal capacitor is an indication of insulation degradation. Tests have shown that the magnitude of this "loss angle" increases with decreasing power supply frequency. Thus, the sensitivity of such measurements is significantly increased when using a VLF power source. The results of the tests are used to establish the required re-test interval.
While the above method provides an overall assessment of insulation condition, it is not as responsive to highly localized defects. To ensure that cables have not been adversely degraded by localized defects and rendered susceptible to switching induced surges, "VLF withstand" testing is performed. This go-no/go method identifies those localized defects and permits repair/replacement before the cable is returned to service.
The tests are described in greater detail in Guides prepared by the Institute of Electrical and Electronics Engineers' (IEEE) Insulated Conductors Committee; IEEE 400 and IEEE 400.2. TVAN actively participated in the development of these guides.
The above tests are required for all new medium voltage installations and replacements (whether safety-related or non-safety-related) and for all existing underground safety-related circuits. The tests are also recommended for existing non-safety-related underground cables which are important to plant operation.
Browns Ferry Nuclear Plant (BFN)
BFN began commercial operation in 1973. BFN has fewer than 10 medium voltage underground safety-related circuits. Assessment of the condition of those cables at BFN began in the summer of 2005. The condition monitoring program has been used to baseline new cable installations and to assess aged circuits used to support the recovery and power uprating of Unit 1. The program has also been used to assess the condition of aged safety and non-safety-related cables associated with the two operating units. Altogether, the program has evaluated approximately 25,000 conductor-feet of aged cable and 13,000 conductor-feet of new cable with approximately 190 "tan delta" measurements and 185 "withstand" tests. The initial round of testing of safety-related circuits is expected to be completed during 2007.
BFN has one duct bank which contains safety-related cables. The bank was designed such that it sloped from the powerhouse to the Intake Pumping Station (IPS) and was intended thereby to remain water free without the need for active sump systems. The addition of fire barrier materials to the box at the ductbank/IPS interface led to a decision to seal the conduits. A sump pump was subsequently installed to remove water which routinely accumulated behind the seal. An existing site repetitive Work Order on manhole cleaning and maintenance (which covers both safety and non-safety-related duct banks) was revised to include the subject handhole within its scope to ensure that the sump pumps are functioning and that trash accumulation does not render them ineffective. This activity is scheduled every twenty-four weeks.
Sequoyah Nuclear Plant (SQN)
SQN began commercial operation in 1981. SQN has fewer than 20 medium voltage underground safety-related circuits. Assessment of the condition of those cables at SQN (using VLF) began in 2003 following the discovery of water treeing at the site of an in-service failure. The CCMP described above was used to verify that the cables were in acceptable condition and to prioritize replacements of the degraded portions of those circuits. The initial round of tests has been completed as have any indicated replacements. Existing circuits are now subject to retesting at the interval dictated by the results of that initial round of "tan delta" assessments. To date the program has evaluated approximately 304,000 conductor-feet (approximately 196,000 conductor-feet of aged, 108,000 conductor-feet of new) utilizing approximately 275 "tan delta" measurements and 160 withstand tests.
These tests complement manhole inspection efforts which have been in place since the early 1990s when SQN modified their safety-related manhole covers to permit ready assessment of water depth. In addition, a Preventative Maintenance (PM) procedure was written to ensure that a periodic assessment is made of manhole conditions (and thus the performance of the sump systems). This PM is scheduled every four weeks.
Watts Bar Nuclear Plant (WBN)
WBN began commercial operation in 1996. WBN has 20 medium voltage underground safety-related circuits. The initial round of testing for these cables required to support Unit 1 is expected to be completed in 2008. Testing of other cables at WBN in their CCMP began in October 2006. One circuit, approximately 1650 conductor-feet of aged cable, has been tested thus far and found to be in acceptable condition. Shortly before WBN startup, the plant identified the need to strengthen its procedures and performance in keeping manholes dry. As a result, manholes containing safety-related cables were modified to add a rotating light which turns on at high sump level, a second light which provides positive indication that there is power to the pump, and a pump run time meter. Plant Operations checks the status and operability of the rotating lights on a weekly basis. A PM also exists for inspection of these manholes which is scheduled every 6 months to ensure that the sump systems are adequately maintained and that trash is not allowed to accumulate within the duct banks which might subsequently impact sump performance. PMs for other manholes which do not contain safety-related cables (and do not have the positive indication systems described above) are scheduled on 6-month intervals.
Low Voltage Cable The TVAN CCMP does not specifically monitor low voltage cables for degradation due to potentially wet environments. As evidenced by the failure data provided, there is no indication that there are issues associated with low voltage power cables. Also, there is no consensus diagnostic testing methodology available that can be performed on unshielded cables.
Underground low voltage, safety-related, power cables are installed in the same duct banks as those medium voltage cables described above and thus would benefit from the same water abatement measures.
- Browns Ferry Nuclear Plant - In-Service Failures Years Normally Service Voltage Cable Rated Vendor/
Date of ain Installation Type Root Cause of Failure Plant Cable End Device Name Energized?
(kV)
Voltage (kV)
Insulation Failure Service f
Y/N
.48, 4.16, 6.9
.6, 5, or 8 yrs BFN ES88-1 (0-MTR -023-0005)
Y 4.16 5
General -
2007 Note 1 Duct bank In-service failure - Evaluation in process RHRSW PUMP MTR. A2 XLPE BFN 3PL1 025 (3-MTR-64-1 1A) REAC.
Y 0.48 0.6 Unknown 2005 Note 1 Embedded conduit In-service failure - Unknown EXH. FAN 3A BFN 2PP1127 (2-MTR-27-18) CCWP 2B Y
4.16 Note 3 Unknown -
2002 Note 1 Buried conduit In-service failure - Unknown CAP. BANK FDR.
XLPE BFN PPI171 COOLING TOWER UNIT Y
4.16 Note 3 Note 2 2001 Note 1 Trench In-service failure - Unknown SUBSTATION TRANSFORMER 6D BFN PP1172 COOLING TOWER UNIT Y
4.16 Note 3 Note 2 2001 Note 1 Trench In-service failure - Unknown SUBSTATION TRANSFORMER 6C BFN ES325-1 FCV-67-49, POWER Y
0.48 0.6 Brand Rex -
2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be FEEDER XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN ES350-1 KINNEY CAB. A (EECW Y
0.48 0.6 Brand Rex -
2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be STRAINER (A) SUPPLY)
XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN ES363-1 KINNEY CAB.D (EECW Y
0.48 0.6 Brand Rex -
2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be STRAINER (D) SUPPLY)
XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN K307 EVACUATION ALARM Y
0.48 0.6 Okonite -
2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be SYSTEM EPR determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN ES825-1 RHRSW PUMP COMPT Y
0.48 0.6 Rockbestos 2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be A, SUMP PUMP A
- XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN ES829-1 RHRSW PUMP COMPT Y
0.48 0.6 Rockbestos 2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be B, SUMP PUMP A
- XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN ES833-1 RHRSW PUMP COMPT Y
0.48 0.6 Rockbestos 2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be C, SUMP PUMP A
-XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
- Browns Ferry Nuclear Plant - In-Service Failures Plant Cable End Device Name Service Voltage CableRated Vendor Dateof in Installation Type Root Cause of Failure Energized?
Voltage (kV) insulation Failure Ser.ice YIN
.,48,4.16,6.9
-~.6, 5, or 8.
yrS BFN ES837-1 RHRSW PUMP COMPT Y
0.48 0.6 Rockbestos 2001 Note 1 Duct bank, note 4 In-service failure - Definitive cause could not be D, SUMP PUMP A
- XLPE determined. According to the laboratory report, "No evidence of global degradation was noted from any stressor (water, chemical, thermal)."
BFN 2PP1 129 CCWP 2C CAP BANK Y
4.16 Note 3 Unknown -
1999 Note 1 Buried conduit In-service failure - Unknown FEEDER (2-MTR -027-XLPE 0026)
BFN 3PP1 144 3-MTR-027-0026 CCWP 4.16 5
Triangle -
1997 Note I Buried conduit In-service failure - Laboratory examination 3C CAP. BANK FEEDER XLPE concluded that the cable failed due to the presence of contaminants in the insulation. No large water trees were observed.
BFN PL3216 480V COOLING WATER N
0.48 0.6 Unknown 1996 Note 1 Duct bank In-service failure - Crushed duct bank MOG BD ALT. FEEDER BFN PP1340 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 6B BFN PP1341 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 6B BFN PP1150 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 1A TRANSFORMER BFN PPl151 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 1 B TRANSFORMER BFN PP1152 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 1C TRANSFORMER BFN PPI153 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 1D TRANSFORMER BFN PP1235 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 1A BFN PP1236 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 1A BFN PP1245 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 1 B BFN PP1246 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 1 B BFN PP1 175 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 5C TRANSFORMER BFN PP 1176 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 5D TRANSFORMER
- Browns Ferry Nuclear Plant - In-Service Failures Years PlantNormally Service Voltage Cable Rated Vendor Date of in Installation Type Root Cause of Failure Energized?
(kV)
Voltage (kV)
Insulation Failure Service Y/N
.48, 4.16, 6.9
.6, 5, or 8 yrs BFN PP1312 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 5A BFN PP1313 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 5A BFN PP1322 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 5B BFN PP1323 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 5B BFN PP1169 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 6A TRANSFORMER BFN PP1170 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 6B TRANSFORMER BFN PP1171 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 6C TRANSFORMER BFN PP1172 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 6D TRANSFORMER BFN PP1 331 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP6A BFN PP1 332 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 6A BFN PP1 154 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 2A TRANSFORMER BFN PP1 155 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 2B TRANSFORMER BFN PP1 159 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 2C TRANSFORMER BFN PP1 160 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 2D TRANSFORMER BFN PP1254 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 2A, PUMPING STATION NO. 2 BFN PP1255 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 2A I
I BFN PP1263 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP2B I
I I
I
- Browns Ferry Nuclear Plant - In-Service Failures Years Plant Cable End Device Name Normally Service Voltage Cable Rated Vendor/
Date of Type Root Cause of Failure Energized?
(kV)
Voltage (kV)
Insulation Failure
-Service Y/N
.48, 4.16, 6.9
.6, 5, or 8 yrs.
BFN PP1264 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 2B BFN PP1358 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 2A CAP BANK FEEDER BFN PP1362 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 2B CAP BANK FEEDER BFN PP1360 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 2A CAP BANK FEEDER BFN PP1 161 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 3A TRANSFORMER BFN PP1 162 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 3B TRANSFORMER BFN PP1 163 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 3C TRANSFORMER BFN PP1 164 480V COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown UNIT SUBSTATION 3D TRANSFORMER BFN PP1275 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 3A BFN PP1276 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 3A BFN PP1284 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 3B BFN PP1285 COOLING TOWER Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown PUMP 3B BFN PP1366 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 3A CAP. FEEDER BFN PP1370 COOLING TOWER PUMP Y
4.16 Note 3 Note 2 1993 Note 1 Trench In-service failure - Unknown 3B CAP. FEEDER BFN PP1 173 480V COOLING TOWER Y
4.16 Note 3 Note 2 1978 Note 1 Duct bank/trench In-service failure - Unknown UNIT SUBSTATION 5A TRANSFORMER Note 1: The year in-service dates cannot be accurately determined.
Note 2:
Note 3:
Note 4:
Cable type and manufacturer cannot be verified based on plant documentation.
The cable rated voltage cannot be accurately verified based on procurement documentation during this time frame.
Failed cables were installed in a single duct.
- Browns Ferry Nuclear Plant - Test Failures P
Normally Service Voltage Cable Rated Vendor/
Date of Years Plant Cable End Device Name Energized?
(kV)
Voltage (kV)
Insulation Failure Service Installation TypeRootCauseofFailur Y/N
.48,4.16, 6.9
.6, 5, or 8 yrs BFN IPP1129 (1-MTR -027-0026)
Y 4.16 5
Triangle -
2005 Note 1 Buried conduit Test failure - Cable failed during VLF withstand CCWP.1C CAP. BANK XLPE test at 7 kV after 10 minutes. Cause unknown.
FEEDER Note 1: The year in-service date cannot be accurately determined.
- Sequoyah Nuclear Plant - In-Service Failures e Normally Service Voltage' Cable Rated Vendo Date of Years ENergazed Servi Voltage Endl Insulation Failure in Installation Type Root Cause of Failure m
Energized?
(k)
Voltage ()
Insulation Failure Service YiN
.48, 4.16,'6.9
.6, 5, or 8 yrs SQN 2PP71 1 B ERCW MOTOR P-B Y
6.9 8
Cyprus -
06/29/2002 24 Duct bank In-service failure - Laboratory analysis determined XLPE that the failure was the result of water treeing.
SQN PP1946S2 START BUS 2B Y
6.9 8
Okonite -
08/1989 5
Duct bank In-service failure - One phase of the cable (non-EPR (red)
Safety Related) failed in service. A test program was conducted to confirm whether water treeing had occurred. Segments of the failed cable were sent to a laboratory where the insulation was examined both near the fault and remote from it.
The laboratory report stated, "No electrical or water trees were found in any of the cable sections examined microscopically". Failure was attributed to contamination consistent with a screen pack rupture during extrusion.
- Sequoyah Nuclear Plant - Test Failures
' :Years Normal Ily Servi Ice Voltage Cable Rated.
Vendod
' Date of Year Plant Cable End Device Name normally SerVi Voltage CbRt ensul Date in Installation Type Root Cause of Failure Energized?
(kW)
Voltage (W)
Insulation Failure
- Service, Y/N
.48, 4.16, 6.9
.6, 5, or 8 yrs SQN 2PP700B ERCW MOTOR M-B Y
6.9 8
Cyprus -
01/25/2005 25 Duct bank Test failure - Cable failed during a VLF withstand XLPE test at 14 kV SQN 1PP674A ERCW MOTOR J-A Y
6.9 8
Cyprus -
05/20/2004 24 Duct bank Test failure - Cable failed during a VLF withstand XLPE test at 14 kV SQN 1PP687A ERCW MOTOR Q-A Y
6.9 8
Cyprus -
11/04/1994 14 Duct bank Test failure - Cable failed during DC hipot testing.
XLPE Subsequent laboratory analysis showed evidence of a water tree at a cluster of contaminants.
Destructive testing of the failed phase with the fault removed and of removed; adjacent, non-faulted phases demonstrated the contamination to be localized.
6.9 8
Cyprus -
08/1994 14 Duct bank Test failure - Cable failed during DC hipot testing XLPE at 22kV. Subsequent laboratory analysis showed a water tree at a large manufacturing defect (a cluster of contaminants). Destructive testing of the failed phase with the fault removed and of removed; adjacent, non-faulted phases demonstrated the contamination to be localized.
6.9 8
Triangle -
04/03/1994 14 Duct bank Test failure - Cable failed during DC hipot testing XLPE between and 5kV and 6kV. Subsequent laboratory analysis showed a water tree at a large manufacturing defect (a cluster of contaminants).
Destructive testing of the failed phase with the fault removed and of removed; adjacent, non-faulted phases demonstrated the contamination to be localized.
SQN PP1940S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1941S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1947S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1948S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not I__IIIdetermine a cause for the failure.
SON PP1950S2 START BUS 1B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not I__IIddetermine a cause for the failure.
- Sequoyah Nuclear Plant - Test Failures Years Plant Cable End Device Name Normally Service Voltage Cable Rated Vendor/
Date of in Installation Type Root Cause of Failure Energized?
(kV)
Voltage (kV)
Insulation*
Failure Service Y/N
.48, 4.16, 6.9
.6, 5, or 8 yrs_
SQN PP1951S2 START BUS 1B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1952S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1955S2 START BUS 1B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
SQN PP1956S2 START BUS 1 B, 2B Y
6.9 8
Okonite -
03/09/1992 8
Duct bank Test failure - Cable failed during DC hipot testing.
EPR (red)
Subsequent laboratory analysis could not determine a cause for the failure.
- Watts Bar Nuclear Plant - All Failures Years Plant Cable End Device Name Normally Service Voltage Cable Rated Vendor/
Date of il TCl Pln al n
eieNm in Installation Type -Root Cause of Failure Energized?
(kV)
Voltage (kV)
Insulation Failure Service
___Y/N
.48, 4.16; 6.9
.6, 5, or 8 yrs WBN N/A N/A N/A N/A N/A N/A N/A N/A N/A No failures. See text.