ML20059M750
ML20059M750 | |
Person / Time | |
---|---|
Site: | Diablo Canyon ![]() |
Issue date: | 08/17/1993 |
From: | AFFILIATION NOT ASSIGNED |
To: | |
References | |
OLA-2-I-MFP-017, OLA-2-I-MFP-17, NUDOCS 9311190281 | |
Download: ML20059M750 (15) | |
Text
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SUMMARY
Auxiliary Salt Water (ASW) pump 1-2 was' removed from service due to unusual mechanical vibrations and the pump was repaired.
As part of the procedure to return the ASW pump to service, a direct current high potential (Hi-pot) test was conducted. While performing the Hi-pot test on the ASW Pump 1-2 cabling, the insulation broke down at approximately 6 kilovolts (kV). The-test was repeated numerous times to locate the fault and the insulation broke down at lower and lower voltage levels until the cable eventually failed to ground.
Five hundred foot sections on all three phases of.the feeder '
cable were replaced between the 12kV switchgear room and the discharge structure. The Hi-pot test was repeated and all three cable phasas passed. ;
The root cause is under investigation and the' corrective actions to prevent recurrence have not been determined. -Various tests '
are being run to determin'e the cause of this cable failure.
Possibilities are of (1) Manufacturing defects; (2) Installation; (3) Aging; (4) and operating environment (i.e., submergence).
Believe that aging is not a factor An Integrated Problem Response _ Team was foraad-on 2/18/93 to assist in root cause determination and corrective action formulation.
This draft, dated March 12, 1993 documents.the meeting minutes for the TRG held on March 11, 1993.
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TRG TO RECUNVENE ON APRIL 1, 1993 @ 1:00 pm TO REVIEW THE
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INVESTIGATIVE ACTIONS AND ATTEMPT TO DETERMINE THE ROOT CAUSE.
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T NCR DC1-92-EM-N054 Rev. 00 l DRAFT: March 12, 1993 4 NCR DC1-92-EM-N054 Hi-pot on Auxiliary Saltwater Pump Motor 1-2 Cable Failed I. Plant Conditions Unit 1 was in Mode 5 (Cold Shutdown) at 0% power.
II. Description of Event A. Summary:
Auxiliary Salt Water (ASW) pump 1-2 was removed from service due to unusual mechanical vibrations and the pump was repaired. While performing the Hi-pot test on the ASW Pump 1-2 cabling the insulation broke down at approximately 6 kilovolte (kV). The test was repeated numerous times and the insulation broke down at lower and lower voltage levels until the cable eventually failed to ground. All three phases of cable were replaced. The Hi-pot test was repeated to 10.5 kV direct current (dc) and all three cable phases passed.
B.
Background:
Electrical Maintenance Procedure E-54.2 "High Voltage Testing of Electrical Equipment" tests circuits to a higher voltage than the circuit is normally expected to operate. The Hi-pot test that was conducted on the ASW pump 1-2-cables consisted of energizing each of the associated three phase cables, in steps, to 10.5kV de, to ensure that the wiring was acceptable for use with the ASW pumps.
C. Escat
Description:
On October 15, 1992, ASW pump 1-2 was removed from service due to unusual mechanical vibrations. The pump was repaired.
On October 31, 1992, during !Ost-maintenance testing, in accordance with procedure MP E-17.1 (ASW Pump Motor Overhaul), to return the ASW pump to service, a Hi-pot test was conducted. While performing the Hi-pot test on the ASW Pump 1-2 motor, the feeder cable insulation broke down at approximately 6kV dc. The test was repeated numerous times and the insulation broke down at lower and lower voltage levels until the cable eventually failed to ground.
In the process of replacing the three power cables, water was discovered in the ASW 1-2 pull box (BP016) located outside the diesel generator rooms. It is speculated that a storm a few days before the Hi-pot test was the source of the water.
The water was pumped out to acceptable levels.
92NCRWP\92EMN054.KWR Page 2 of 15
6
- NCR DC1-92-EM-N054 Rev. 00
. DRAFT:. March 12, 1993 on November 1, 1992, new cables for all three phases were installed. s on November 4, 1992, the Hi-pot test:was repeated and all three cable phases passed, i
D. Inoperable Structures,-Components,-or Systems that Contributed to the Event:
- l None.
E. Dates and Approximate Times for' Major' Occurrences:
- 1. October'15, 1992; 'ASW pump 1-2 repaired. .
- 2. October 31, 1992: Event / Discovery-date. Hi-pot' test.of Okonite cable identified fault in one phase. ,
j
- 3. November 1, 1992: All.three phases of cable were.
replaced, q
- 4. November 4, 1992: Hi-pot test repeated <ni new cables. .
t 1
F. Other Systems or Secondary: Functions AffectOd:
None. ;
)
G. Method of Discovery:
sw. es .m e wM '
Electrical Maintenance personnel. performed a Hi-pot test in accordance with procedure MP E-54.2 (High-Voltage Testing of Electrical Equipment) and identified the fault in."C" phase .,i l
of the cable.
H. Operator. Actions:
l None.
l ..
I. Safety System Responses:
None.
III. Cause of the Event A. Immediate Cause:
An ASW pump power cable faulted when personnel conducted a l Hi-pot test.
i 92NCRWP\92EMN054.KWR .Page 3 of: 15 l l
E___________.. _ _ _ _ _ .. . , _ . _ . . . . . _ - . . - . . , _ . , , , , , _ , , . . , , - . . ,. , . ,
1 NCR DC1-92-EM-N054 Rev. 00 -
l DRAFT: March 12, 1993 . I B. Determination of Cause:
A cause and effect analysis method will tua used to perform the root cause analysis and will be included in the NCR binder.
C. Root Cause:
To be determined.
l D. Contributory Cause:
1 To be determined.
IV. Analysis of the Event A. Safety Analysis:
Each reactoc unit at Diablo Canyon has two completely redundant ASW trains. A single ASW train is capable of maintaining the unit's component cooling water (CCW) system.
l During normal operation, only one CCW heat exchanger and one ASW train are running, although both trains have to be operable for modes 1 through 4 (TS 3. 7. 4.1) . Either ASW
' train can supply either CCW heat exchanger, by opening and closing the heat exchangers' flow control valves (FCV-602 and I 603). In addition, both units' ASW trains can be cross-tied to add further redundancy to the system. Although both units can be cross-tied, it is normally not the case FCV-601 is normally closed. Since both ASW trains are electrically separate and independent, a cable fault in one ASW train would not have prevented the other train from performing its safety related function.
1 the public was not adverfely Therefore, affected.the ""health and shtety "of
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Unit 1 was in Mode 5 at 0% power during this event.
B. Reportability:
- 1. Reviewed under QAP-15.B and determined to be i non-conforming in accordance with Section 2.1.8.
- 2. Reviewed under 10 CFR 50.72 and 10 CFR 50.73 per NUREG 1022 and determined not to be reportable with the information available at this date.-
3.
! Reviewed under 10 CFR Part 21 and determined that this' problem wil'. not require a 10 CFR 21 report, since it does not involve defects in vendor-supplied services / spare parts in stock.
- 4. This problem has been be reported via an INPO Nuclear Network entry.
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t
t NCR DC1-92-EM-N054 Rev. 00 DRAFT: March 12, 1993 i
- 5. Reviewed under 10 CFR 50.9 and determined to be not reportable since this event does not have a significant implication for public health and safety or common defense and security.
- 6. Reviewed under the criteria of AP C-29 requiring the
V. Corrective Actions A. Immediate Corrective Actions:
- 1. Five hundred foot sections of all three phases-leading to ASW pump 1-2 were replaced and the cables were retested ,
with satisfactory results.
l B. Investfgative Actions:
I 1. Document the cable design. What is the service life? Is it submergence qualified? etc?
RESPONSIBILITY: C. Shortt DEPARTMENT: PGMB Tracking AR: A0283880, AE #01 STATUS: RETURN ,
l 2. List all of the circuits that run from the plant to the l -intake structure. Identify all of the various types of insulation associated with each cable. Determine the impact of a circuit failure on plant operations.
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RESPONSIBILITY: C. Shortt, :.. Hanson-DEPARTMENT: m-PGMB/PGMB Tracking AR: A0283880, AE #02 I
- STATUS
- RETURN. l 1
1
- 3. TES will analyze.the removed cable to determine the cause of the failure.
RESPONSIBILITY: R., Bush ECD: 3/05/93 DEPARTMENT: TEMT Tracking AR: A0283880, AE #03 j STATUS: ASIGNED
- 4. Regulatory Compliance will make an INPO entry documenting j the three failures of Okonite cable.
RESPONSIBILITY: P. Dahan DEPARTMENT: PTRC Tracking AR: A0283880, AE # 04 STATUS: RETURN l'
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i v.i NCR DC1-92-EM-N054 Rev. 00. .
, DRAFT: March 12, 1993' -
I 0
- 5. Investigate the pull for the ASW cable. Determine'how many times'it was pulled ~in and how'many time it'was pulled out. . j RESPONSIBILITY: J. Shortt DEPARTMENT: PGMB Tracking AR: A0283880, AE # 05; STATUS: RETURN
- 6. Perform testing on Unit:2 installed ASW cables-during 2R5,'to. determine the insulation. properties.
RESPONSIBILITY: R. Hanson 1 ECD: 05/31/93'.'. i DEPARTMENT: PGMB Tracking AR: A0283880, AE'# 06 ;
STATUS: ' ASSIGNED
- 7. Look at previous test results to determine'if there is l any trend that shows whether.there is a decrease insulation resistance.
RESPONSIBILITY: R. Hanson . ECD: 02/17/93 i DEPARTMENT: PGEM Tracking AR: A0283880, AE # 07 STATUS: ' ASSIGNED _
t
- 8. Check with. chemistry to determine'what. chemical' changes have taken place in the insulation'in pieces of cable
-near the fault. -
RESPONSIBILITY: V. Wyman ECD: 03/05/93 DEPARTMENT: TES ,
Tracking AR: A0283880,'AE # 08 '
STATUS: Original 7. TURN on 2/8/93.- On'2/18/93~the TRG 'i determined that this-should.be.kept~ASIGND until: ,
the Altran cable chemical analysis'is-received. ;
9..
Have Cable Technology Laboratories' (CTL) ' perform a submergence test. ,
RESPONSIBILITY: V...Wyman . ECD': 08/31/93:
DEPARTMENT: TES' Tracking AR: 'A0283880,'AE # 09 STATUS: ASSIGNED
- 10. Document the (manufacturer) lot numbers for all-three SkV
[ rated) cable failures.
RESPONSIBILITY: W.'Fargo' DEPARTMENT: NECS-EZ (IPRT)
Tracking AR: A0283880, AE # 10 l STATUS: RETUnli 92NCRWP\92EMN054.KWR- :Page' 6 of. 15 I
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' NCR DC1-92-EM-N054 Rev. 00 DRAFT: March 12, 1993
- 11. Obtain samples, for chemical analysis, from within the cable vaults associated with the Unit 1.ASW pump motor feeder cables, located outside the turbine building 12kV switchgear cable spreading room.
RESPONSIBILITY: R. Hanson. ECD: 04/30/94
~
DEPARTMENT: PGEM Tracking AR: A0283880, AE # 11 STATUS: ASSIGNED
- 12. Obtain samples, for chemical analysis, from within the cable vaults associated with'the Unit 2 ASW pump motor feeder cables, located outside the turbine building 12kV switchgear cable spreading room.
RESPONSIBILITY: R. Hanson ECD: 04/30/93 DEPARTMENT: PGEM Tracking AR: A0283880, AE # 12 STATUS: ASSIGNED C. Corrective Actions to Prevent Recurrence:
- 1. Clean out the cable vaults and pull boxes for the Unit 1 ASW pump motor feeder circuits to the intake structure,
~
repair the. associated sump pumps as necessary, and repair the cable vault and pull box lids to help prevent
-moisture intrusion.
RESPONSIBILITY: R. Hanson ECD: 04/30/94 DEPARTMENT: Electrical-Maintenance Tracking AR: A0283880, AE #13 Outage RelatEd? Yes -OUTAGET 1R6 OE Related? No NRC Commitment? No CMD Commitment? No
- 2. Establish a preventative maintenance _ program for the sump pumps and drains associated with the Unit 1 cable vaults <
located outside the turbine building 12kV Switchgear cable spreading rooms.
RESPONSIBILITY: R. Hanson ECD: 04/30/94 DEPARTMENT: Electrical Maintenance Tracking AR: A0283880, AE #14 '
Outage Related? Yes OUTAGE: 1R6 OE Related? No NRC Commitment? No CMD Commitment? No 92NCRWP\92EMN054.KWR Page ,7 of 15
a NCR DC1-92-EM-N054 RGv. 00 -
DRAFT: March 12, 1993 ,
- 3. Clean out the cable vaults and pull boxes for the Unit 2 ASW pump actor feeder circuits to the intake structure, repair the associated sump pumps as necessary, and repair the cable vault and pull box lids to help prevent moisture intrusion.
RESPONSIBILITY: R. Hanson ECD: 04/30/93 :
DEPARTMENT: Electrical Maintenance l Tracking AR: A0283880, AE #15 i Outage Related? Yes OUTAGE: 2R5 !
OE Related? No !
NRC Commitment? No l CMD Commitment? No I
- 4. Establish a preventative maintenance program for the sump l pumps and drains associated with the Unit 2 cable vaults located outside the turbine building 12kV Switchgear i cable sp eading rooms. j l
RESPONSIBILITY: R. Hanson ECD: 04/30/93 ;
DEPARTMENT: Electrical Maintenance l Tracking AR: A0283880, AE #16 Outage Related? Yes OUTAGE: 2RS l OE Related? No NRC Commitment? No i CMD Commitment? No D. Prudent Actions (not required for NCR closure) l To be determined.
VI. Additional Information A. Failed Components:
ASW pump 1-2 feeder cable Manufacturer Information:
Component: ASW pp 1-2 Feeder Cable Manufacturer: Okonite Model Number: CABLE 1/C 2/0 EPR Type: SkV SHLD OKOGUARD-OKOLON B. Previous Similar Events:
NCR DC2-89-EM-N104 On October 29, 1989, ground alarms annunciated and immediately cleared. A ground was found on the "A" phase cable to the ASW pump motor 2-2. A portion of all three phases were replaced and tested. No root cause could be identified after extensive testing by TES and the manufacturer, Okonite. No corrective actions to prevent recurrence were identified. Therefore, the current event was not prevented.
92NCRWP\92EMN054.KWR Page 8 of 15
r NCR DC1-92-EM-N054 Rev. 00 ,
DRAFT: March 12, 1993 l QE Q0009710 l On May 3, 1992, brief spurious ground alarms were received. A ground was found in one cable between the 4kV bus D and bus 14D. The pull box containing the cable l was found to have a considerable amount of water inside..
Approximately 40 feet of cable was replaced and the faulty section was sent to TES and Okonite for testing.
No cause for the fault could be determined and no corrective actions were identified. Therefore, the current event was not prevented.
1 C. Operating Experience Review:
I
- 1. NPRDS:
None.
i
- 2. NPC Information Notices, Bulletins, Generic Letters:
IE Information Notice No. 86-49: Age / Environment Induced Electrical Cable Failures.
On November 21, 1985, San Onofre Unit i experienced a loss of offsite power when a transformer was tripped by its differential relays because of a failed cable to the class 1E 4160-V bus. The most likely cause of the cable failure was determincd to be temperature-induced accelerated aging and degradation of the
- cable insulation. The notice also stated "Another important facet of the periodic maintenance and testing program for cable circuits is the walkdown inspection to identify actual or potential environmental conditir s (heat, water, enemicals,
' ~"
etc.) in the immediate vicinity of.the cables that could adversely affect cable conditions.
PG&E's response to this notice was that DCPP's class 1E cable outside of the spreading areas and switchgear rooms is run inside rigid iron conduit and is properly routed away from high temperature piping and equipment.
IE Information Notice No. 92-81: Environmental Qualification of Control Cables.
Based on tests conducted by Sandia National Laboretories for the NRC, certain electrical cables with bonded Hypalon jackets may not meet environmental qualification requirements. Sandia conducted tests on cables manufactured by three different companies to determine the minimum insulation thickness necessary to perform its intended function should the insulation be damaged 92NCRWP\92EMN054.KWR Page 9 of 15
k NCR DC1-92-EM-N054 Rev. 00 .
DRAFT: March 12, 1993 -
during installation, mainteneace, Eor.other activities. During LOCA. testing, all 10 of the Okonite-Okolon cable samples failed. The test specimens were single-conductor, 600 volt,.12 AWG control cables insulated with ethylene-propylene rubber (EPR) with bonded-Hypalon jacket.
.Information Notice 92-81 was issued to address NRC concern with environmental qualification of Okonite cables with. bon'ded Hypalon jackets that have not been qualified for service conditions ; exceeding 50"C .for 40 years. According to.the NRC,. qualification testing that does'not'use the actual. jacket service configuration may not be. representative of; actual-cable performance. The' Staff cautions that the integrity of cables could be affected if the cables
- are used inside containment, used'in continuous power circuits,' routed with power cables, cnr routed close to hot piping. .
This information notice is not applicable to'the 4kV cable failure since the 4kV cable is does not require environmental qualification, does.not use a Hypalon jacket,'and the neoprene-jacket.is not bonded to the cable shield / insulation.
None.
D. Trend Code:
.~.asponsible dapartz.c-+ __, and cause~ code __. ,
E. Corrective Action Tracking: 1
- 1. The tracking action request is A0283880.
- 2. Are the corrective actions outage related?iNo.= l F. Footnotes and Special Comments:
None. .
.i G.
References:
- 1. Initiating Action Request A0283650.,
- 2. TES memorandum report dated February 5, 1990, "DCPP Unit 2 ASW Pump 2-2 Electrical Feeder Cable Failure Analysis."
92NCRWP\92EMN054.KWR Page. 10 of. 15 I
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-1 ,
I s ~
NCR DCi-92-EM-N054 Rev. 00 DRAFT: March 12, 1993
- 3. Okonite Engineering Report dated February 12,. 1990.
- 4. TES Laboratory Test Report No. 420DC-92-856 dated i September 10, 1992.
- f. Specification No. 0702 for Furnishing and Delivering of High Voltage Power Cable for Units 1 and 2 - Diablo '
Canyon Site.
- 6. Chronology of events for ASW 1-2 cable failure. ,
- 7. INPO Network Entry MI-10496, entered 2/3/93.
- 8. NCR Tracking Action Request A0283880.
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1 l
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~NCR DC1-92-EM-N054 Rcv. 00' . ,
DRAFT: March 12, 1993 ,
H. TRG Meeting Minutes: l
- 1. On November 3, 1992, the TRG convened and considered the ;)
following: j The event was reviewed and discussed.
The three cables that were removed will be shipped to TES for analysis.
A large quantity of water was oiscovered in one of the l pull boxes _that housed 1the ASW pump 1-2 cable, submerging i
those cables. l The following investigative actions were assigned: (1) document the cable design. What.is the service life? Is it submergence qualified? etc?; (2) list all of the ,
circuits that run from the plant to'the intake structure. l Identi.y all of the various types of insulation i associated with each cable.' Determine the impact.of a circuit failure on plant operations; (3) TES will analyze the removed cable to determine the cause of the failure.
The TRG agreed to reconvene on 11/17/92 to review the investigative actions.
)
- 2. On November 18, 1992, the TRG reconvened to discuss the following:
TES has received the three spouls of cable and will start testing. Earliest time for results is the. middle of December.
Extensive testing of~ the cable will"litclude: (1) partihl discharge 15kV ac corona testing;.(2) power factor testing; (3) ac/dc withstand proof testing; (4) insulation resistance testing; (5) AC breakdown testing; (6) physical testing (tensile and elongation); (7) dissection of the area with the fault.
Since this is the third failure of'this type of Okonite cable, the generic concerns: were discussed. Pending the outcome of the testing, this. issue will be.re-addressed.
The TRG agreed to reconvene on 1/15/93 to discuss the test results from TES.
- 3. On January 20, 1993 the TRG reconvened and' considered the followinG; Telephone conference with Vern Wyman, TES San-Ramon.
Waiting for test.results from Okonite.
92NCRWP\92EMN054.KWR Page 12 of 15
s NCR DC1-92-EM-N054 Rev. 00 DRAFT: March 12, 1993 Could not find at this time anything to pinpoint the root
( cause.
1 It is not known if it is an isolated failure. !
A submergence test is to be conducted by CTL.
There could be some contamination or imperfections in the insulation.
Need to take 30 to 40 feet of cable and look for imperfections in the insulation.
Saw something like a " monument", but decided that this was caused by the slicing. (1989 TES test report)
Need to run a partial discharge test. The chemical analysis on the insulation is Ethylene Propylene Rubber (EPR). There is possibility that there was some damage during the pulling process. Need to recover the pull records.
All the testing at Cable Technology, Inc. is not complete. Should have a draft by February.
Possibilities of:
- 1. Manufacturing defects.
- 2. Installation.
- 3. Age related. Believe that aging is not a factor.
- 4. Environment.
This material is Enviror.-'ntally Qualified (EQ).
~ Qualification under submergence. Seven days water absorption. Leakage measurement. Micro Amp leakage measurement at each cable.
See IPCEA publication. S-68-516.
IPCEA S-19 5th edition.
Six investigative actions, numbers 4-10, were initiated.
TRG TO RECONVENE ON FEBRUARY 18, 1993 TO REVIEW THE INVESTIGATIVE ACTIONS AND ATTEMPT TO DETERMINE THE ROOT CAUSE.
- 4. On February 18, 1993 the TRG reconvened and considered )
the following; ASW pump 2-1 will be overhauled during 2RS. As post-maintenance testing, the pump will be hi-pot tested from the 4kV switchgear at 10.5kVDC. The cables will not be determinated for the hi-pot testing.
92NCRWP\92EMN054.KWR Page 13 of 15
/
NCR DC1-92-EM-N054_Rev..00 ,
DRAFT March 12,.1993 e i The TRG reviewed the status of the-investigative _ actions.. _
NOTE: an Integrated Problem Response Team.-(IPRT)Ehas_been formed to investigate recent 4kV and 12kV. failures and will make a recommendation to this TRG/NCR.
Initial review of the previous test.results (REF: .. ,
A0283880, AE 07) provides no indication ~of.a.trendable- ~!
degradation. The data.will.be turned over to Predictive '
Maintenance (PM) ~for review and plotting. '
PM will j provide input to the IPRT.- '
Preliminary results from Cable Technology Laboratories j (CTL) indicates voids of up'to 10! mils within_one, inch of '
forced high-voltage breakdown testing. failure point. .The.
testing and cable examination needs,to be repeated'to determine if this is'an isolated case. NOTE: . PG&E' Spec ;
0702 requirement was 5 mil voids. CTL preliminary )
opinion is that, if these areLvalid voids, then.the i frequency of cable failure will' increase.
'After preliminary investigation, TES has. determined that the causes of the 4kV and.12kV cable failures _are different. The best indicator of'a change in the composition of the' insulation material are the tensile and elongation tests. So for, testing has shown these properties have changed very little since the-4kV cable-was manufactured.
_After preliminary investigation, Okonite'has determined that the physical and electrical properties of the insulation are not. degraded. Okonite_cannot: find a. ,
reason for the failures. R The TES repoti 4e expected on_3/5/93-and will'make j
recommendations based on the CTL, Okonite, and TES test i results. The final, report will-incorporate _the cable ~
installed environment,.i.e. submergence, as part ofuthe failure analysis. Based o'n this report recommendation, a one time " proof"'hi-potitest.may be required to demonstrate the adequacy of the installed cable. This !
proof test would-be performedJon. cable-with the same manufacturer lot number as the' failed cable.
New Investigative Action: Document the' manufacturer-lot numbers for all three SkV? cable failures. This is an IPRT investigative' action.
Available cable on hand is'approximately'three ree~ls of-2800 feet each (2 orange, 1 grey).- This cable is-the newer Okonite " red" EPR. Estimated replacement costs is
$3.17 per foot with a~33 week lead time.
92NCRWP\92EMN054.KWR Page- 14 cf .15
NCR DC1-92-EM-N054 Rev. 00
' DRAFT:' March 12, 1993 TRG TO TENTATIVELY TO RECONVENE ON MARCH 9, 1993 TO REVIEW THE INVESTIGATIVE ACTIONS AND ATTEMPT TO DETERMINE THE ROOT CAUSE.
- 5. On March 11, 1993 the TRG reconvened and. considered'the following; Test goals of the CTL submergence testing were discussed.
It was confirmed with Verne-Wyman of TES, and concurred by the TRG, that.the testing will be as follows: After stripping the neoprene jacket and conductor. shield, the cable ~will be: submerged for at least fourteen days. ,
After submergence, capacitance measurements will;be obtained and then a controlled voltage breakdown test will be conducted. .The submerged results will be compared to pre-submergence results. Test should be complete with results by March 19, 1993..
Root cause analysis has proved-inconclusive so far since there are still many potential contributors.
One contributor that is expected to be addressed by this NCR (or by the IPRT process) is " Cable-vaults and/or pull boxes not properly draining."
Investigative action for this contributory cause will; be to.obtain swipes from within the ASW pp cable vaults for chemical-analysis.
Corrective actions for this contributory cause are'to clean out the pull boxes,' repair the cable. vault sump-pumps, and reseal'the pull box lids from water
" = - intrusi-on. =~ '
Unit 2 ASW pump motor cable testing was discussed.-
Electrical Maintenance will.hi-pot.both: circuits with-the motors. connected as per past practice. In addition, the shield insulation resistance ~will be measured and compared to an Okonite supplied value.
With no further action possible until~after receipt 1of' Altran 4kV chemical analysis and the CTL' submergence test results, the TRG adjourned.
TRG TO RECONVENE ON APRIL 1 0'1:00 pm,'1993'TO REVIEW THE INVESTIGATIVE ACTIONS AND TO DETERMINE THE ROOT CAUSE.
I. Remarks:
None.
92NCRWP\92EMN054.KWR Page 15 .of 15