ML18064A883

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LER 95-007-00:on 950720,discovered That 12 Instrument Loops Had V-bolted Type Qualified Cable Splices Connected to Wires W/Exposed Kapton Insulation.Caused by Human Error.All V- Bolted Splices Replaced w/in-line design.W/950821 Ltr
ML18064A883
Person / Time
Site: Palisades Entergy icon.png
Issue date: 08/21/1995
From: Haas K, Roberts W
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-007, LER-95-7, NUDOCS 9509070182
Download: ML18064A883 (9)
v • d • e


Text

.e consumers Power KurtM.Haas Plant Safety and Licensing Director Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 August 21, 1995 U S Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT LICENSEE EVENT REPORT 95-007 EXPOSED KAPTON CABLE INSULATION RESULTS IN UNQUALIFIED EQ CABLE SPLICE Licensee Event Report (LER)95-007 is attached. This event is reportable in accordance with 10 CFR 50.73 (a)(2)(ii)(B) as a condition outside the plant design basis.

SUMMARY

OF COMMITMENTS This letter contains no new conunitments and no revisions to existing commitments.

Kurt M. Haas Plant Safety and Licensing Director CC Administrator, Region III, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades Attachment

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\..V~L~J.j 9509070182 950821 PDR ADOCK 05000255

  • s PD.R A CM5 ENERGY COMPANY.

NRC Form 388 U.S. NUCLEAR REGULATORY COMMISSION (9-831 APPROVED OMB NO. 316().()104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT ILER)

FACILITY NAME 111 DOCKET NUMBER 121 PAGE 131 Palisades Plant 0 6 0 0 0 2 6 6 OF 0 7 T1TlE 141 LICENSEE EVENT REPORT 95-007 - EXPOSED KAPTON CABLE INSULATION RESULTS IN UNQUALIFIED EQ CABLE SPLICE EVENT DATE 1151 REPORT DATE 181 OTHER FACILITIES INVOlVED 181 REVISION FACILITY NAMES MONTH DAY YEAR . YEAR NUMBER MONTH DAY YEAR N/A 0 & 0 0 0 0 7 2 0 9 5 9 5 0 0 7 00082196 N/A o tS o o* o ..

THIS REPORT 18 SUBMITTm PURSUMT TO THE REQUIREMENTS OF 10 CRI I: /CIWdl - * - oltM ~ 1111 OPERATINO MOD! Ill N 20A02Cbl 20.406(c) ll0.731a11210vl 73.71Cbl 20.406Cel11101 110.se1c1m ll0.7Slall21M 73.71Ccl 20.4061a1C110il llO.S81cll21 ll0.731all21Mll OTHER CSpedfy In Abstract 20.4061*11110iil ll0.731a112101 llO.731a1121MlllCAI below and In Tut.

20.4061a1C1 llM x ll0.731all210il ll0.731all21MlllCBI NRC Form 388.AI 20.4061a1C1 IM ll0.73Call2111iil ll0.731all21bd LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER WILLIAM L ROBERTS, STAFF LICENSING ENGINEER AREA CODE 6 1. 6 7 6 4 8 9

. MAN UFAC- REPORT ABLE MANUFAC*

CAUSE SYSTEM COMPONENT TURER TO NPROS CAUSE SYSTEM COMPONENT TURER TONPRDS SUPPLEMENTAL REPORT EXPECTm 1141 MONTH DAY YEAR EXPECTm SUBMISSION YES Uf yw, _,,,..,. EXPECTED SUBMISSION DA TEI DATE 11&1 On July 20, 1995, the plant was in cold shutdown for a refueling outage. Because of a problem identified with a splice completed during a transmitter replacement as part of the refueling outage, a corrective action was initiated to review the other environmentally qualified splices that are inside of containment. During this review it was discovered that 12 instrument loops had V-bolted type qualified cable splices connected to wires with exposed Kapton insulation which has been shown to degrade over time when exposed to the steam and water chemistry of a LOCA.

The 12 V-bolted splices were replaced with qualified in-line splices which cover the Kapton insulation.

NRC Form 388A U.S. NUCLEAR REGULATORY COMMISSION (9-831 APPROVED OMB NO. 316CH>104 EXPIRES: B/3118&

LICENSEE EVENT REPORT CLER) TEXT CONTaNUATION FACILITY NAME 111 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant olol1 olo 012 OF 011 EVENT PESCRIPIION On July 20, 1995*, the plant was in cold shutdown for a refueling outage. Because of a problem identified with a splice completed during a transmitter replacement as part of the refueling outage, a corrective action was initiated to review the other environmentally qualified splices that are inside of containment. During this review it was discovered that 12 instrument loops had V-

  • bolted type qualified cable splices connected to wires with exposed Kapton insulation which has been shown to degrade over time when exposed to the steam. and water chemistry of a LOCA.

The 12 V-bolted splices were replaced with qualified in-line .splices which cover the Kapton insulation.

During this review it was discovered that 12 instrument loops had V-bolted type splices connecting Rosemount conduit seal pigtail wires to instrument field cable. The V-bolted design is a common splice configuration that has been pre-qualified by Raychem (the splice material

.manufacturer). The design of a V-bolted splice (drawing SK-splice attached) requires that the outer jacket of the cable containing the wires to be spliced, be stripped back so that only the individual insulated conductors enter the splice. This typically exposes 2 to 5 inches of the .i insulated conductor between the point where the cable jacket stops and the splice begins. The **

12 V-bolted splices identified are all inside of junction boxes with weep .holes (an EEO i

requirement) drilled in the bottom. The problem with these splices is that the conductors of the Rosemount seal leadwires are insulated with Kapton. Kapton insulation has been shown to degrade over time when exposed to the steam and water chemistry of a LOCA. Since the junction boxes.containing the V-bolted splices have weep holes in the bottom of the box, the Kapton insulation could be exposed to a post LOCA steam and water chemistry environment.

The following transmitters had the V-bolted splice with exposed Kapton wire.

LT-0752A, B, C, D - Steam Generator E-508 level LT-0757A, B -Steam Generator E-50A wide level LT-0758A, B -Steam Generator E-508 wide level PT-0751 A, B, C, D - Steam Generator E-508 pressure These splices were installed in December, 1985, by FC-624.

This condition is reportable in accordance with 10 CFR 50. 73(a)(2)(ii)(B) as a condition outside the plant design basis.

CAUSE OF THE EVENT Since the information was available showing that Kapton insulation would degrade in a post accident steam and water chemistry environment, it should have been found and applied.

Therefore it is concluded that human error in not finding and using the information on Kapton

NRC Form 388A U.S. NUCLEAR REGULATORY COMMISSION

  • (9-831 APPROVED OMB NO. 316<Hl104 EXPIRES: 8/31186 LICENSEE EVENT REPORT CLER) TEXT CONTINUATION FACILITY NAME C11 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBSI Palisades Plant . -*.: :J o Io f 1 olo ol3 o" 011 *: =;~f
    • ~- .. ~~}-

insulation in the Rosemount Qualification Report is the root cause. . .  :~:

There are three causes contributing to this problem: the weakness of the EEO program as .it*

existed in 1985; the lack of information on Kapton; and finally, that those. engineers inyolved.

with the modification did not find and question what the Kapton-findings.from the Rosemount* -")

qualification testing might mean to our installations. * * * * *. **

ANALYSIS OF THE EVENT AFFECTED EQUIPMENT The primary function of the affected instrumentation was tripping the reactor or actuation of a safety feature. The secondary function was monitoring. The Technical Specifications requirements for the instrumentation affected are as follows:

Technical Specifications, Section 3.17, *instrumentation Systems*, Table 3.17.1,

  • instrumentation Operating Requirements for Reactor Protective System*

Low* A* Steam Generator Level Low*e* Steam Generator Level Low* A* Steam Generator. Pressure Low*e* Steam Generator Pressure Technical Specifications, Section 3.17, *instrumentation Systems*, Table 3.17 .2,

  • instrumentation Operating Requirements for Engineered Safety Features"
3. Auxiliary Feedwater Actuation Signal (AFAS)
  • instrumentation Operating Requirements for Isolation Functions"
3. Steam Generator Low Pressure (SGLP)

NRC Form 3eeA U.S. NUCLEAR REGULATORY COMMISSION 19-831 APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME Ill DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant olol1 olo ol4 o, 011 11 . Wide Range *A* Steam Generator Level

12. Wide Range *e* Steam Generator Level
14. Narrow Range *A* Steam Generator Pressure
15. Narrow Range *e* Steam Generator Pressure FAILURE MECHANISM Kapton insulation, when exposed to high temperature steam or direct chemical spray begins to lose its dielectric or insulating properties. Direct exposure to accident steam will have the same effect. The most likely effect of this degradation would be leakage current between the positive and negative conductors of the instrument loop, resulting in an erroneous instrument reading.

At Palisades the affected transmitters and their junction boxes are all located inside containment above the post accident flood level. Liquid could, however, enter the junction boxes housing the splices via unsealed conduits and steam could enter via the weep hole drilled in the bottom of each junction box. From information drawn from the Rosemount conduit seal qualification report,

  • Type Test Report for Model 353C, D8300200, Rev e*, and from Sandia Labs report NUREG/CR-

. 5772, SAND91-1766/3, Vol. 3, *Aging, Condition Monitoring, and Loss-of-Coolant Accident (LOCA) Tests of Class 1E Electrical Cables" a conservative estimate of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> would elapse from the start of the accident to where enough degradation. of the Kapton insulation had occurred to affect the instrument accuracy.

HOW IT HAPPENED Environmental Qualification Program Historv In 1985, the Environmental Qualification (EQ) program was managed within Plant Modifications &

Miscellaneous Projects (PM&MP), an engineering organization supporting both fossil and nuclear power plants. PM&MP was located off site in Jackson, Michigan and reported to a Vice President not specifically responsible for nuclear operations.

Palisades Plant involvement was essentially limited to performing walkdowns to confirm as-built conditions of EO-listed equipment. The plant staff did not have ownership of the EQ program.

Development and maintenance of EO files, environmental qualification testing and analysis, and communication with the NRC were the responsibility of PM&MP.

During this time period, significant replacement of EO listed equipment was implemented to meet the NRC's newly published EO Rule, 10CFR50.49. Several large scope modification packages were used to modify many pieces of equipment to comply with the new Environmental Equipment Qualification regulatory guidelines. Design work was shared by both Bechtel and Consumers PM&MP group.

NRC Form 388A U.S. NUCLEAR REGULATORY COMMISSION (9-831 APPROVED OMB NO. 31~104 EXPIRES: B/31 /B6 LICENSEE EVENT REPORT CLER) TEXT CONTINUATION FACILITY NAME 111 DOCKET NUMBER 121 UR NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0 I0 I7  ; 0 I0 0 I5 OF *O I7 The records show that the original design was for in-line splices for all the transmitters affected by the modification. The modification package contains a Record of Telecon, dated October 14, 1985 between one of the CPCo engineers and one of the Palisades Electrical Contractor's engineers. The CPCo engineer asked Contractor's engineer whether or not two in-line splices would fit in each of the junction boxes that existed for the -0751 and -0752 series of transmitters. The Contractor's engineer checked and called the. CPCo engineer back indicating that the *stub co.nnection" (V-bolted) design for the splices would have to be used for the two instrument loops in each J-box. That criteria must have been extended to the -0757 and -0758 series transmitters as well, as these splices are also of the V-bolted design.

  • During the discussions with the two CPCo Engineers* involv.ed in the original EO work for Palisades during this evaluation, both stated they were unaware of the problem with Kapton insulation and LOCA steam/water chemistry.

Information on the problems encountered with Kapton were documented in the original Rosemount qualification report, however it was discussed in a manner that might not have caused the engineers to realize they would have a problem.

The EQ program was not technically strong during the time in which these design change packages were developed. Engineering guidelines and procedural controls, In effect today to assure that EO requirements are understood and met by design change engineers, did not exist at that time. Formal training for engineers responsible for EQ did not exist as it does today. The design change process used by PM&MP differed from that used by the Plant, at times making it difficult to obtain effective Plant review.

In 1986, EO files were transferred to the plant site and plant engineering staff took over management of the EQ program. Since that time the plant engineering department eliminated redundant design change processes, developed EQ procedural controls, developed engineering guidelines (including EQ guidelines), and conducted EO training for engineers.

The type of engineering error reported in this corrective action document does not go undetected today as evidenced by the recently reported discoveries.

Kapton History Industry experience using Kapton insulation is generally quite good when installed in accordance with the manufacturers instructions. NRC Information Notice 88-89 has a treatise of industry problems as well as known failure mechanisms for the Kapton insulation. The Information Notice also notes that Kapton insulated wiring is used in virtually every Nuclear Power Plant (Conax penetrations, Conax seals, Rosemount transmitter seals, etc.). In summary, it can be concluded from the notice that use of Kapton insulated wire in Nuclear applications is acceptable if it is protected from mechanical damage during installation and not exposed directly to high temperature steam or post LOCA chemical environment.

NRC Form 388A U.S. NUClEAR REGULATORY COMMISSION (IHl31 APPROVED OMB NO. 31~104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME C11 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEOU&mAL REVISION YEAR NUMBER NUMBER Palisades Plant olol1 0 I0 0 I6 OF 0 I7 Palisades has reviewed the Sandia report NUREG/CR-5772, Vols 1, 2, & 3 dated August 1992 and November 1992, and has used the information as reference material for EQ qualification packages. The information contained in the Sandia reports cannot .be used as qualification data as it was not performed under an Appendix B quality assurance program .. From recent review of this r~port, there was very little information in the Sandia report that was germane to the .

Rosemount conduit seal issue, including Kapton Insulation or undersized Raychem sleeving.

Palisades has conducted an industry search on Kapton issues through MOS and NUS. The information notices cited in IN 88-89 (IN 87-08, IN 87-16), and one EPRI Report (NP-7189) provide the only information that was related to Kapton issues. Contacts with other nuclear utilities during the research phase have also indicated an awareness of installation restrictions on Kapton *insulated wire.

The V-bolted splice design was accepted in 1985. In mid 1987, the manufacturer acknowledged to the NRC that Kapton could degrade under steam or post LOCA chemical spray conditions.

Discovery of the problem at individual plants would have required knowledge of the detailed EQ requirements as well as the specific installation details.

The Rosemount and Conax seal assemblies are the only known sources of* Kapton insulated wire

  • in the EQ program at Palisades. ~th of the EQ files for these assemblies reference the Palisades response to IN 88-89 contained in E48, sheet 9 regarding Kapton insulated wiring. In the mid 80's time frame, it does not appear that each installation would have been reviewed by an EQ specialist. Even if the splice installation was reviewed, it would have been in late 1988 when the information notice was evaluated before a potential problem would have been recognized with the installation. When these two files are upgraded later this year, a specific note on the manufacturers cautions for installation will be added - specifically that the Kapton insulation shall not be allowed to be used when contact with water/steam/chemical spray is likely.

SAFETY SIGNIFICANCE For the A steam generator, only the wide range level indication was affected by this issue.

Failure of this indication after an accident would be backed up by other qualified level transmitters.

For the B steam generator, the wide range level, narrow range level and pressure were affected.

These instruments provide two safety functions, automatic RPS actuation or SIG isolation, and long term accident monitoring. Since degradation of the affected instruments is not postulated until later in the accident these instruments would have performed their automatic function prior to being degraded.

Since the instruments would have been expected to survive for at least three hours, the impact on long term accident monitoring would be minimal. Within three hours a majority of the

NRC Form S88A U.S. NUCLEAR REGULATORY COMMISSION

' (9-831 APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION .

FACILITY NAME 111 DOCKET NUMBER 121 LEA NUMBER C31 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0 f0 0I 7 OF 0 I7 operator action~ for the accident have been accomplished. At a minimum the loss of these instruments would have no impact on accident mitigation. In the worst case the operators would have to enter the Functional Recovery Emergency Operating Procedure (EOP-9). Operators are well trained on the use of EOP-9 under degraded containment c,ondition$. . **

For the above reasons the safety significance for both the automatic action*s and long term accident monitoring functions. of t~ese. instruments is minimal.

CORRECTIVE ACTION

1. CORRECTIVE ACTIONS TAKEN AND RESULTS ACHIEVED FES-95-232 was initiated to cut out the 12 Bolted V splices and replace them with Rosemount designed and qualified in-line splice that would cover and protect the exposed Kapton insulated wire. LT-0758A is also having its Rosemount conduit seal replaced with a Rosemount seal having a tonger pigtail to eliminate a second splice in the circuit. As of l 8/8/95 all V-bolted splices have been replaced with an in-line design qualified by Rosemount, the transmitter manufacturer. **
2. CORRECTIVE ACTIONS TO AVOID RECURRENCE Palisades current modification processes require review by an E_EO engineer, of all modifications that involve Environmental Qualification. It is, therefore, highly unlikely_ that this type of problem could recur. The EEO engineers currently on staff have had considerable more training than did the staff of 1988. Lessons learned from this event, however, will be reviewed with all the engineering staff at an upcoming engineering training session.

ADPIIIONAL INFORMATION

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TO

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CONSUMERS POWER CO.

PALISADES PLANT V-BOLTED SPLICE DETAIL St£ET REY SK-SPLICE 1 A

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