ML20207E163
| ML20207E163 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/10/1986 |
| From: | Beck J, Bizzak R, Mallanda J TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | |
| Shared Package | |
| ML20207E095 | List: |
| References | |
| NUDOCS 8701020079 | |
| Download: ML20207E163 (39) | |
Text
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K COMANCHE PEAK RESPONSE TEAM l
RESULTS REPORT 1..
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ISAP:
I,b.2 l
Title:
Flexible Conduit to Cable Separation y
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REVISION 1 Vy d
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1 Page 1 of 39 RESULTS REPORT ISAP !.b.2 Flexible Conduit to Cable Separation
1.0 DESCRIPTION
OF ISSUE IDENTIFIED BY NRC (NUREG-0797, Supplement No. 7-Page J-42)
"The TRT determined that the installation of certain safety-or nonsafety-related cables inside control room panels, which were in direct contact with safety-related flexible conduits associated with the other redundant trains (see Table 1), was inconsistent with engineering drawings and regulatory requirements... Because acceptability of the flexible conduit as a barrier was not established by analysis, as required by Section 5.6.2 of IEEE Standard 384, the cables cust be separated frem the conduits inside the panels by a minimum distance of 6 inches, as required by Section 5.6.2 of IEEE Standard 384."
)
2.0 ACTION IDENTIFIED BY NRC (NUREC-0797, Supplement No. 7 Item 6(b),
Page J-44)
"TUEC shall accomplish the following actions prior to fuel load:
Eithericorrect each of the violations of separation criteria concerning separate cables and cables within flexible conduits found in contact with each other inside main control room panels (Table 1) or demonstrate by analysis the adequacy of the flexible
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conduit as a barrier. TUEC shall also reinspect all remaining panels in the control room and other areas of the plant containing separate cables and cables within flexible conduit and shall take the same corrective actions as those outlined in Table 1.
This analysis shall be accomplished in accordance with Section 5.6.2 of IEEE Standard 384-1974. In 'the event that the acceptability of the conduit as a barrier cannot be demonstrated, TUEC shall separate cables and cables within flexib1'e conduits by a minimum distance of 6 inches, as required by Section 5.6.2 of IEEE Standard 384.
Furthermore, TUEC shall correct all appropriate drawings and documents to indicate the revised min.imum separation."
3.0 BACKGROUND
The cases of cables being in direct contact with the SERVICAIR flexible metallic conduit identified by the NRC under this action plan are contrary to the project cable separation requirements delineated on Drawing 2323-El-1702-02, " Cable and Raceway Separation Typical Details"; a one-inch separation should have been provided.
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1 Page 2 of 39 1/
RESULTS REPORT d
ISAP I.b.2 (Cont'd) 3:
3.0 BACKGROUND
(Cont'd)
- The main concern expressed by the NRC-TRT team is that the SERVICAIR flexible metallic conduit
- used in the control room
- panels has not been shown by analysis to qualify as a barrier **.
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- Both IEEE 384-1974, "IEEE Trial-Use Standard Criteria for i
Separation of Class LE Equipment and Circuits," and IEEE 420-1973, "IEEE Trial-Use Guide for Class IE Control Switchboards for Nuclear i ower Generating Stations," recognize metallic conduit as an P
i acceptable barrier in lieu of a minimum six-inch separation between redundant *** cables. -Since SERVICAIR flex is a metallic conduit, it was judged by the Project to be an acceptable barrier in accordance with the Standards, and no specific testing and/or analyses was considered necessary.
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'In the' construction of nuclear power plants, it is necessary to ensure that isolated failures of individual safety systems do not cause consequential damage to and possible failure of redundant safety systems. In the area of electrical cabling, this assurance historically has been provided by specifying and enforcing y{m}'
requirements on the minimum allowable physical separation of redundant, safety-class cables or by requiring the use of physical barriers to protect redundant cable trains. The specified separation must be maintained throughout the length of each cable.
IEEE 384-1974, "IEEE Trial-Use Standard Criteria for Separation of Class IE Equipment and Circuits," IEEE 420-1973, "IEEE Trial-Use Guide for Class IE Control Switchboards for Nuclear Power Mrating Stations," and Regulatory Guide 1.75, Revision 1,
" Physical Independence of Electric Systems", which are generally accepted as the documents governing electrical separation requirements and which are applicable to the CPSES (Comanche Peak The flexible conduit used for separation inside the control room panels is SERVICAIR flexible metallic conduit (referred to in this j
report as SERVICAIR flex or flex).
As defined'in IEEE 384-1974, a barrier is "a device or structure interposed between Class LE equipment or circuits and a potential source of damage to limit damage to Class 1E systems to an acceptable level."
- -All separation requirements in this report are for redundant cables. The word " redundant" as used herein means that the cables
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requiring separation belong to different traine, i.e., Class 1E
.j train A, Class IE train B, or non-Class LE train C.
Revision:
1 Page 3 of 39 r_7s RESULTS REPORT
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.8hy 'i ISAP I.b.2' (Cont'd) l
3.0 BACKGROUND
i(Cont'd)
Steam Electric Station)' Project, f ndicate that within electrical panels and cabinets, " metallic contuit" is an acceptable separation barrier in lieu of~ physical separation. Therefore, rigid metallic conduit has been recognized'by the nuclear industry as an acceptable barrier inside electrical panels.
However, there are situations wh'ere maintaining sufficient physical separation is difficult or_ impossible and for which rigid conduit is an unsuitable alternative. Hand switch modules in the CPSES control, boards are an example. LBy design, these modules have redundant cables in close proximity to each other. ; Additionally, it-is required to have slack in the cables attached to these devices to accommodate routine maintenance and adjustment of the controls. As a result, rigid metallic conduit cannot be used to solve the separation problems associated with these devices.
This same. situation has arisen elsewhere in the nuclear industry and has been successfully resolved by the installation of SERVICAIR L (['
flexible metallic conduit as a_ barrier. After obtaining IEEE N__/
323-1974 and IEEE 344-1975 environmental and seismic qualification data for the SERVICAIR flex and after discussions with the supplier of the control boards (Reliance Electric Company), TUGC0 issued design change documents at Comanche Peak specifying the use of SERVICAIR flex as a barrier.
Then the Project. criteria were modified in November 1979 to specify the use of SERVICAIR flex, its use was limited to the main control boards. The use of SERVICAIR flex was expanded in October 1980 to include all panels supplied by Reliance Electric Company (procured under Purchapa Order CP-0605 to Specification 2323-MS-605, " Nuclear Safety Related Control Boards"),'which include the control room control boards and vertical ventilation panels.
In November 1980, a Design Change Authorization (DCA) was issued to the Electrical Erection Specification 2323-ES-100 that listed SERVICAIR flex as metallic conduit, thereby allowing its use as a separation barrier in all electrical panels. For the reasons stated previously, TUGC0 undertook no specific effort to qualify this material as a barrier.
The above facts notwithstanding, the NRC-TRT expressed a concern that SERVICAIR flex used in the CPSES control boards had not been qualified as a barrier through appropriate analysis and/or testing.
This action plan was designed to address the TRT's concern by
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demonstrating the adequacy of SERVICAIR flex as a barrier.
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1 Page 4 of 39
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.RESULTS REPORT
'ISAP I.b.2 (Cont'd) 3.0;IBACKGROUND (Cont'd)'
Many of the activities described in this report are the same as or similar to the activities described in the Results Report for Action-Plan I.b.1, " Flexible Conduit to Flexible Conduit Separation." Nonetheless, the descriptions of these activities are repeated'herein for the reader's convenience.
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4.0 - CPRT ACTION PLAN 4.1 Scope and Methodology t
The objectives of this action plan were 1) to determine, by testing and analyses, the minimum acceptable separation distance between a cable enclosed within SERVICAIR flex and a redundant, exposed cable, i.e. a cable not in conduit, and 2) to reinspect all panels which contain redundant cables that could violate the final separation. criteria
- for SERVICAIR D-j flex to an exposed cable.
7V The following tasks were implemented to achieve these objectives:
Circuit evaluation and thermal analyses to demonstrate the adequacy of SERVICAIR flex as a barrier Testing to demonstrate the adequacy of SERVICAIR flex as a barrier Inspections of cabics in the control reos control boards and vertical ventilation panels for adequate separation Trocedure/ Drawing revisions to incorporate the final separation criteria Examination of panels other than the control boards and vertical ventilation panels for the use of SERVICAIR flex The final separation criteria (see Table 2) are the separation criteria developed as a result of this action plan. See DCA 21,446, Revision 1, to Drawing 2323-El-1702-02, " Cable and
.(
Raceway Separation Typical Details" and Section 5.4.
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1 Page
-5 of'39 l
RESULTS REPORT A
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.ISAP.I.b.2 q
.f (Cont'd)
. 4.0 <CPRT ACTION PLAN.(Cont'd)
The. majority (over ninety percent).of the SERVICAIR flex is located in'the control room control boards and vertical ventilation panels.. Therefore, the analyses, testing, and inspections described above were based on the circuits and configurations'present in these panals. The remaining Unit I and common' area panels with two or mere trains were examined by the Electrical Review Team to identify the location of all SERVICAIR flex.
4.1.1' Analyses 4.1.1.1 Circuit Evaluation An evaluation of circuits in the control boards and vertical ventilation panels was performed to determine the maximum current available for the control circuits. This information was used to help establish the ff)\\ '
was used to determine those circuits which test conditions for the testing described ps_
below. In addition,~this circuit evaluation contain multiple series protective devices and those circuits for which the maximum faulted current is insufficient to result in heat damage to the subject circuits themselves. or adjacent cables. For these t's circuits, less stringent criteria for separation from other redundant circuits may be used. This is allowed per Paragraph 5.6.2 of IEEE 384-1974. The circuit evaluation specifically addressed the modular wiring to hand switches where the required cable slack creates difficulties in maintaining fixed spatial separation. Other circuits that are in close proximity to the hand switch module wiring were also included in the evaluation.
No specific circuit evaluation was planned for circuits contained in panels other than the control boards and vertical ventilation panels. For those cases where SERVICAIR flex is used in panels outside of those evaluated, the acceptability of SERVICAIR flex as a barrier requires further evaluation on a
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case-by-case basis.
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1 Page 6 of 39 f
RESULTS REPORT 1_
J ISAP I.b.2 (Cont'd) 4.0 -CPRT ACTION PLAN (Cont'd) 4.1.1.2..
Thermal Analyses Thermal analyses, supported by the results of tests described in Section 4.1.2, were performed to determine the adequacy of SERVICAIR flex as a barrier. These analyses were based on the heat transfer characteristics of the cable and SERVICAIR flex and apply to this action plan, " Flexible Conduit to Cable Separation," as well as Action Plan I.b.1, " Flexible Conduit to Flexible Conduit Separation."
4.1.2 Test Program A two-part test program was conducted to determine the adequacy of the SERVICAIR flex as a barrier.
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The first part of the test program was designed to determine the ability of SERVICAIR flex to carry a short circuit current without inflicting damage to cables contained in adjacent or touching SERVICAIR flex. In this test, two flex conduits were placed perpendicular to one another, touching at one point.
One lead from the current source was attached to one SERVICAIR flex; the other lead to the other SERVICAIR flex. Test currents representative of the maximum possible fault currents from the control boards' and vertical ventilation panels' power supplies were applied during the tests. The test current flowed along one flex, across the point of contact, and then along the second flex (both flex conduits were isolated from ground). A cable was inserted in one of the flex conduits to serve as a " target" cable to enable monitoring of any damage incurred by cables contained in SERVICAIR flex due to the current in the flex.
The second part of the test program was designed to determine the ability of the SERVICAIR flex to act as an effective thermal barrier between a cable (within SERVICAIR flex) experiencing an overload condition and a redundant cable either exposed and one inch away or contained within an adjacent SERVICAIR flex. For this test a source cable was placed inside a one-inch SERVICAIR fler and subjected to several different i
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1 i
Page 7 of 39 r
.N RESULTS REPORT
!v ISAP I b.2 (Cont'd) 410 CPRT ACTION PLAN (Cont'd) currents.
A. target cable was placed inside a 5/8-inch SERVICAIR flex which was in contact with the one-inch SERVICAIR flex; a second exposed target cable was placed one inch above the one-inch flex. Surface temperatures of the two pieces of flex and the exposed target cable were monitorad throughout the test, as well as the temperatures of the faulted conductors.
The test procedures were written and tests conducted such that the test results are applicable to the control room control boards and vertical ventilation panels. The procedures for the test program were prepared by the Third-Party Adviser, in conjunction with Gibbs & Hill, and approved by the Electrical Review Team Leader prior-to implementation of the test program.
L(j~'y' 4.1.3 Investigations / Inspections
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4.1.3.1 Preliminary Investigations Concurrent with the above testing and analysis program, an inspection of the Unit 1 control boards and vertical ventilation panels was performed to determine the extent to which SERVICAIR flex was used as a barrier.
Separation guidelines based on preliminary, conservative separation distances were provided by Gibbs & Hill for review and approval by the Electrical Review Team Leader. Third-party inspectors inspected the control boards and vertical ventilation panels using these guidelines to determine the extent of potential modifications required for compliance with the final separation criteria. In addition, this investigation provided input as to the types of cable insulation used in the control boards and vertical ventilation panels. This 4
information, in turn, was used to determine the scope of the testing and to identify O
additional circuits that should be included in the circuit evaluation described above.
d Revision:
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'Page 8 of 39 m
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RESULTS REPORT
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ISAP 1.b.2-(Cont'd) 4.0 CPRT ACTION PLAN (Cont'd)
These inspections involved all aspects of cable separation, including the issues addressed in Action Plan I.b.1, " Flexible Conduit to-Flexible Conduit Separation," and Action Plan I.b.4, " Missing Barriers."
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The intent was to compare the CPRT third-party inspection findings against the final separation criteria. Those third-party findings that did not meet the final-s separation criteria were to be reported on Nonconformance Reports (NCRs).
4.1.3.2 TUGC0 Inspections Prior to issuing NCRs for the findings identified by the CPRT third-party, TUGC0
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validated the findings, using the final separation criteria. For those findings
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1 which clearly violated the final separation criteria NCRs were issued. Another group of findings were acceptable when compared to the final separation criteria, since some of the attributes of the final separation criteria were less stringent than those used by the CPRT third-party. For other findings where the minimum separation distance was reduced by the final criteria, it was difficult to
' determine from the third-party reports if the 3
less stringent, final criteria were met, since the actual separation distances had not been recorded.
To resolve this issue, the Electrical Review Team Leader initiated, through the TUGC0 Coordinator, an inspection of all third-party findings that did not clearly violate the (c
final separation criteria.
Since the final separation criteria had changed to be more restrictive than the previous Project criteria, it was decided
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that a reinspection of the panels for those separation attributes that were revised to be more restrictive be performed concurrently with the above validation of the CPRT
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t Revision:
1 Page 9 of 39 RESULTS REPORT b
ISAP I.b.2 (Cont'd)
.4.0ECPRT ACTION PLAN (Cont'd).
third-party findings. 'This inspection would provide the inspection of record for the control boards and vertical ventilation panels.-
4.1.3.3 Third-party Overview In addition to the above TUGC0 inspection, there will be a post-construction inspection performed by TUGC0 after all rework resulting from outstanding Nonconformance Reports for Action Plans I.b.2 and I.b.4 has been completed. CPRT third-party personnel will
,p overview this final inspectior.
.4.1.4' Procedure / Drawing Revisions Based on the results of the above analyses and testing.
.Ni TUGC0 revised Drawing 2323-El-1702-02, " Cable and
-\\m_/
Raceway Separation Typical Details" to reflect the
- ' final separation criteria. This drawing provides the separation criteria used by the Project.
The applicable QC inspection procedures were also revised to reflect the proper docunents that specify
'the final separation criteria.
These above document changes were reviewed by the Electrical Review Team Leader, as discussed in Section 5.6.
4.1.5 Examination of Other Panels for SERVICAIR Flex A100$examinationofallpanelsinUnitIandcommon areas containing two or more trains was performed by the CPRT Electrical Review Team to determine where SERVICAIR flex was used outside the control room control boards and vertical ventilation panels. Since this action plan addresses the use of SERVICAIR flex in the control boards and vertical ventilation panels O
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1 Page 10 of 39 4
[ j-RESULTS REPORT' u
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'ISAP I.b.2 (Cont'd) f4.0 LCPRT ACTION PLAN (Cont'd)-
only, the acceptability.of SERVICAIR flex as a barrier
^
.in other panels' requires further evaluation on a cm case-by-case basis by TUCCO. The CPRT third-party
-overviewed this evaluation for those cases where flex was found in panels other than the control boards and a
- vertical ventilation panels.
4.1.6 Use of Results For Unit 1 and common areas, all deviations from the final separation criteria were noted. They were identified and dispositioned on Nonconformance Reports,
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!and rework will be performed as required. For Unit 2, installation procedures and QC inspection procedures
- have been or are being revised to ensure that personnel are aware of the required separation criteria. This, in turn, will result in panel configurations that meet
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the specified requirements.
i 4.2 Participants Roles and Responsibilities The organizations and personnel that participated in this effort are described below with their respective work scope.
4.2.1 TUGC0 Comanche Peak Project 4.2.1.1 Revised QC inspection procedures and will revise craft procedure to include new criteria resu'. ting from tests and analyses.
Will retrain craft and inspection personnel to the new criteria.
4.2.1.'
Revf sed Drawing 2323-El-1702-02, " Cable and Racewcv Separation Typical Details", and other related documents, to reflect the final separation criteria.
4.2.1.3 Performed reinspections for the Unit I control room control boards and vertical ventilation panels for those final separation attributes which have been revised to be more restrictive as a result of this action plan.
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Revision
- 1 Page 11 of 39 j
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1RESULTS REPORT
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l ISAP I.b.2 (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.2.1.4 Will process NCRs that were generated in connection with this action plan.
4.2.1.5 Personnel Mr. W. I. Vogelsang TUCCO Coordinator 4.2.2 Electrical Review Team 4.2.2.1 Reviewed the analyses, circuit evaluation, test results and revised QC inspection procedures. Will review revised craft procedure.
4.2.2.2 Completed 100% examination of all panels with two or more trains to identify cases where SERVICAIR flex is used outside the control
-c room control boards and vertical ventilation panels.
4.2.2.3 Reviewed the inspection reports and will review the NCRs generated as a result of this action plan.
4.2.2.4 Reviewed and approved the test procedures and test report.
4.2.2.5 Reviewed changes to Drawing 2323-El-1702-02,
" Cable and Raceway Separation Typical Details", and other related documents, which reflect the final separation criteria.
4.2.2.6 Reviewed documentation of training of TUGC0 Project inspectors to final separation criteria.
4.2.2.7 Will overview the TUGC0 post-construction inspection of the Unit I control room control boards and vertical ventilation panels.
4.2.2.8 Determined root cause, generic implications and safety significance, as required.
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1 Page 12 of 39 RESULTS REPORT ISAP I.b.2 (Cont'd) 4.0 - CPRT ACTION PLAN (Cont'd) 4.2.2.9 Personnel (prior to October 18, 1985)
Mr. M. B. Jones, Jr.
Review Team Leader Mr. E. P. Stroupe Issue Coordinator 4.2.2.10 Personnel (starting October 18, 1985)
Mr. J. J. Ma11anda Review Team Leader Mr. R. J. Bizzak Issue Coordinator Mr. M. B. Jones, Jr.
Third-Party Adviser Mr. E. P. Stroupe Third-Party Adviser 4.2.3 CPRT'- QA/QC Review Team y%
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4.2.3.1 Inspected Unit 1 control roca control boards and vertical ventilation panels which have SERVICAIR flex for compliance to separation guidelines (see Section 4.2.5.4).
4.2.3.2 Will perform overview inspection (see Section 4.2.2.7) as determined by the Electrical Review Team.
4.2.3.2 Personnel Mr. J. L. Hansel Re. view Team Leader 4.2.4 Third-Party Adviser 4.2.4.1 Prepared test procedures.
4.2.4.2 Supervised the tests.
4.2.4.3 Issued a report of the test results.
4.2.4.4 Reviewed the circuit evaluation, as required.
4.2.4.5 Personnel Mr. L. D. Bates Third-Party Adviser
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l' Pags 13 of 39
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RESULTS REPORT
.fl Q ;[
.ISAP I.b.2 (Cont'd)
N.0; CPRT ACTION PLAN (Cont'd) 4.2.5 Gibbs & Hill 4.2.5.~1 Performed circuit evaluation and thermal analyses.
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4.2.5.2 Assisted in preparation of the test procedures.
4.2.5.3 Reviewed and approved the test report.
4.2.5.4 Prepared separation guidelines for CPRT third-party inspectors.
4.2.5.5 Prepared. final Project separation criteria.
4.2.5.6
~ Assisted in tha QC inspections, as required.
4.2.5.7 Assisted in the processing of NCRs that were p)
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generated in connection with this action
. plan.
4.2.5'.8 Personnel Mr. S. P. Martinovich Principal Electrical Engineer 4.3 Qualific'ation of Personnel Where inspections required the use of certified inspectors, qualification at the appropriate level was to the requirements of ANSI N45.2.6, " Qualification of Inspection, Examination, and Testing Personnel at Nuclear Power Plants." CPRT third-party inspectors were certified to the requirements of the third-party employer's Quality Assurance program, and
.specifically trained to the CPRT Program Plan.
Where tests required the use of certified test personnel, J
qualification at the appropriate level to the requirements of ANSI N45.2.6 and Regulatory Guide 1.58 was not met.
These requirements were not part of the CPRT Program Plan at the time of testing. However, the qualifications of the individual supervising the tests were considered by the Review Team Leader to be more than sufficient to render the tests valid.
7 Third-party participants in the implementation of this action plan met the personnel qualification and objectivity requirements of the CPRT Program Plan and its implementing procedures.
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' 1 Page' 14 of-39
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RESULTS REPORT
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ISAP I.b.2 (Cont'd)
/
'40 CPRT ACTION PLAN-(Cont'd),
g
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Other participants were qualified to the requirements of the CPSES Juality Assurance Program or to the specific requirheents of the CPRT Program Plan. CPRT activities performed by other than. third-party personnel were governed by the applicable principles of Section III.K, " Assurance of CPRT Program Quality", of the CPRT Program Plan.
4.4 Procedures The'following CPRT procedures were developed in support of this Action Plan:
4.4.1 Procedure I.b.1-001, " Cable /SERVICAIR Heat Transfer Test".
4.4.2 Procedure I.b.1-002, "SERVICAIR Short Circuit Test"
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L.4.3 Instruction QI-004, "CPRT Action Item I.b.1 - Flexible k',,').-
Conduit to Flexible Conduit Separation; CPRT Action j
Item I.b.2 Flexible Conduit to Cable Separation".
4.5 Acceptance Criteria 4.5.1 The acceptance criterion was that the SERVICAIR flex be shown by testing and/or analyses to be an acceptable barrier as provided by IEEE-384 (1974), IEEE-420 (1973) and Regulatory Guide 1.75, Revision 1, January, 1975.
4.5.2 The acceptance criterion for cable to SERVICAIR flex
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separation is that the cable and flexible conduit not touch each other and that the separation provided meets the requirements stipulated in Drawing 2323-El-1702-02,
" Cable and Raceway Separation Typical Details" (see Sectier. 4.2.1.2).
4.6 Decision Criteria i.
If the tests and analyses results did not qualify SERVICAIR flex as a barrier, qualified barriers were to be installed or 6" separation provided and the applicable documents revised to indicate the revised minimum separation for SERVICAIR flex.
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Ravision:
1 Paga 15 of 39 I
RESULTS REPORT c
l IS A'P. I. b. 2 (Cont'd)
L.0 J DISCUSSION OF RESULTS -
5 JL chronology of1the major activities discussed in this Results
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' Report is provided in Attachment 1.
5.1 ' Summary'
'The first objective of this action plan was to determine through testing and analyses the minimum acceptable separation distance between cables of-redundant trains, when only one of
' the cables is enclosed within SERVICAIR flex. Since SERVICAIR flex was used mainly in the control room control boards and vertical ventilation panels, the program described below was based.on the circuits in those panels.
The first step was a circuit evaluation to determine the -
- maximum credible overload or short circuit current that should be used in the subsequent testing. 'In addition, various circuits were evaluated to determine if they could be shown not to cause damage to adjacent cables either because they
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were incapable of carrying high currents or because they contained multiple protective devices in series.
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An investigation of.the cables in the control boards and vertical ventilation panels was then undertaken using preliminary, conservative separation guidelines. This investigation provided an-assessment of the extent to which SERVICAIR flex was used as a barrier. Furthermore, the I
investigation provided data on the type of cable insulation used, i.e.. Tefsel* versus non-Tefzel.
Internal wiring by Reliance Electric is all Tefzel-insulated; field wiring to the terminal blocks in the back of the panels is mostly non-Tefsel. The field investigation provided preliminary confirmation that the majority of the areas where separation could be a problem involved only Tefzel cable. Therefore, the testing that was performed during the same time frame as these investigations was limited to Tefzel cables. Those circuits that most commonly used non-Tefsel cables were assessed relative to the circuit evaluation that had already been performed and additional evaluations were performed to justify less stringent minimum separation distances for these additional circuits.
O Tefsel is DuPont's registered trademark for fluoropolymers used for, among other things, conductor insulation and cable jacketing.
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Revision:
1 e, <7, b Paga' 16 of'39 1
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RESULTS REPORT LP ISAP I.b.2 (Cont'd) 5.0 DISCUSSION OF'RESULTS (Cont'd)
>A two-part test program was conducted to determine the
' adequacy of SERVICAIR flex as a barrier for Tefzel. ables.
The first test was designed to determine the ability of.
SERVICAIR flex to carry a short circuit current without
' inflicting damage to cables contained in adjacent or touching SERVICAIR flex, even if the short' circuit current passed from
-the SERVICAIR flex containing the faulted circuit to the SERVICAIR flex in contact with it.
The second test was designed to determine the ability of SERVICAIR flex to act as c
an effective thermal barrier between an overloaded circuit.
contained in the SERVICAIR flex and either a redundant cable contained in SERVICAIR flex touching.the first piece of flex or an exposed cable one inch away.
The case of an exposed cable one inch from a flex containing a faulted circuit was performed in support of this action plun.
Subsequent to the testing program, parametric computer analyses were performed to' determine the effectiveness of
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SERVICAIR flex as a thermal barrier for a range of
\\I configurations. Parametert such as current level, flex size,
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-flex length, and flex orientation were examined to determine the effect that these parameters would have on the maximum flex surface temperature.
The second objective of this action plan was to reinspect all electrical panels which contain redundant cables in SERVICAIR flex that could violate the final separation criteria. The CPRT third-party identified nonconforming conditions involving
-separation of SERVICAIR flex to exposed cables in the control boards and vertical ventilation panels based on the preliminary, conservative separation guidelines developed by Gibbs & Hill. When the final separation criteria were developed. TUGC0 QC inspectors performed a validation of the CPRT third-party findings and a reinspection of these panels to the final separation criteria.
For panels other than the :ontrol boards and vertical ventilation panels, the CPRT Electrical Review Team performed an examination of all multi-train electrical panels to determine where else SERVICAIR flex were used.
Since the testing and analyses that were performed to show that SERVICAIR flex is a barrier were based on the circuits present in the control boards and vertical ventilation panels, the use Os' of SERVICAIR flex in other panels would require further evaluation on a case-by-case basis to demonstrate the acceptability of SERVICAIR flex as a barrier.
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1 Page 17 of 39 RESULTS REPORT
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ISAP I.b.2 (Cont'd) i ip 5.0 DISCUSSION OF RESULTS (Cont'd) 5.2 Testing A two-part test program was undertaken to determine the adequacy of SERVICAIR flex as a barrier when Tefzel cables contained therein are subjected to electrically-initiated failures.
The first part of the test program was designed to determine the adequacy of the SERVICAIR flex to provide a path for short circuit current without causing damage to cables in an adjacent or touching flex. The_ circuit in the test set-up consisted of two pieces of flex in contact with each other, crossing at approximately 90 degrees. A target Tefzel-insulated cable was inserted in one of the two pieces of flex. One lead from the current source was attached to one SERVICAIR flex; the other lead was attached to the other SERVICAIR flex. The flex conduits were isolated from ground, which resulted in the curront passing from one flex to the
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other at the point of contact. The circuit breaker test set used to supply current for these tests was preset to deliver a 2000 amperes DC current when applied to a single piece of flex. Using this machine setting, current was applied to the test circuit three times with a 30-ampere fuse in the circuit and three times without a fuse. The most severe cases were those run without a fuse. During the first such case without a fuse, the circuit breaker test set was preset to trip automatically. For the last two cases without a fuse, the current was manually interrupted shortly after two seconds, which is much longer than the time normally required for a fuse or circuit breaker to open. The test current for the case of automatic machine interruption was 1560 amperes; the maximum test current for the cases involving manual interruption was 1102 amperes.
It should be noted that although the test equipment was set to deliver 2000 amperes through a single piece of flex, the current in the test passed from one flex to the other (both ungrounded) and the additional resistance due to the contact point between the two pieces of flex reduced the current. Nonetheless, the test currents were representative of the maximum fault currents that can be postulated to occur in the control boards and vertical ventilation panels.
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RESULTS REPORT k
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ISAP.I.b.2 A pi (Cont'd)
~ 5.0 DISCUSSION OF RESULTS (Cont'd)
The only cases that resulted in any damage during these tests were those where the test currents were applied to the two pieces;of flex without a fuse in the test circuit-and without automatic machine interruption. The outer bronze braids covering the steel bodies of the flex conduits became welded together at the contact point..Nonetheless, there was no damage to'the steel body of either SERVICAIR flex. The cable inside the smaller 5/8-inch flex was not damaged. This was verified' by post-test visual examination of the cable jacket for signs of Tefsel melting.' In addition, megger testing of-
.the cable did not indicate any damage to the cable.
.As a result of these tests'it was concluded that SERVICAIR flex could carry currents representative of the maximum fault currents expected at the control boards and vertical ventilation panels without imposing damage to Tefzel cables in an adjacent touching flex even if the f ault current were to
~ flow through both of the touching flex conduits.
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.Since the cable.inside the current carrying flex was not damaged, an exposed cable one inch away from the flex would likewise not be damaged.
1 The second part of the test program investigated the heat transfer characteristics of SERVICAIR flex. The test setup included a source cable inside a one-inch SERVICAIR flex. A target cable was placed inside a 5/8-inch SERVICAIR flex in contact with the one-inch flex. An exposed target cable was j
placed one inch above the one-inch flex. As current was L
applied to a circuit enclosed within the one-inch diameter
.SERVICAIR flex, the temperatures of the copper conductors and the outside surfaces of the two pieces of flex were moni:ored, as well as the air teuperature one-quarter inch above the flex and the temperature of the exposed conductor one inch above the flex. Current levels were varied from fifteen to forty amperes per energized conductor (four conductors were energized to represent the worst case of concurrent faulting of two circuits within the same flex feeding a single piece of equipment). The upper-bound current of forty amperes was selected since the circuits involved are protected by circuit 3
protection devices (i.e., fuses or circuit breakers) rated at 30 amperes or less; fuses are used exclusively for protection above 20 amperes. Per UL Standard 198B, a current of 135 percent of the fuse rating will open the circuit within one iaO hour. Therefore, the maximum substained current for these
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circuits in the control boards is less than 40.5 amperes.
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Page 19 of 39 RESULTS REPORT
+1 SAP I.b.2 (Cont'd)
-5.0 DISCUSSION OF RESULTS (Cont'd)
The results of this testing showed that the Tefzel insulation melted only during the forty ampere case, during which the energized conductors reached a maximum temperature of 350*C.
Even then, the maximum surface temperature of'the flex containing the overloaded circuits was only 149'C.
The maximum measured temperature of the cable one inch from the flex containing the overloaded circuits was 65'C.
As discussed in Section 5.3.1, these temperatures were shown to be acceptable.
5.3. Analyses 5.3.1 Thermal (Post-Test) Analyses for Tefzel Cables Subsequent to the completion of the heat transfer tests, computer analyses were performed in which
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several of the test parameters were varied, such as
/ ~s current level, flex size, flex length, and flex
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orientation. This parametric study was performed to determine the maximum flex surface temperature due to a faulted circuit within the flex and also to provide quantitative answers to the following questions:
If the protection device malfunctioned, would a current higher than 40 amperes give a higher transient flex surface temperature prior to insulation melting than was experienced in the 40 ampere test case?
Since the melting of the Tefzel insulation during the test significantly reduced the temperature of the copper conductors, and hence the temperature of the SERVICAIR flex, would the flex temperature be higher at the current level ccrresponding to the point just prior to gross melting of the insulation?
How do the results apply to the other sizes of SERVICAIR flex used at Comanche Peak (i.e., 5/8-inch-diameter flex and 2-inch-diameter flex)?
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~RESULTS REPORT pf ISAP.I.b.2 (Cont'd) 5.0 > DISCUSSION OF,RESULTS (Cont'd)
How does the orientation of the flex affect the results?' The testing was done for a horizontal piece of flex. A vertical flex would have a lower convective film coefficient..and, therefore, could have a higher surface temperature.
l What effect does the length of SERVICAIR flex have on the maximum temperature?
The initial step in the computer analyses was to develop a model and analyse it at the same current levels used in the testing program. Th's time history temperatures from the computer analyses and the tests were compared and refinements were made to the computer model until the computer results were' validated.by the test results. The computer model for a one-inch flex
.w-was then used to analyze six different current levels ranging from thirty-two and one-half amperes to sixty asperes. The steady-state. flex temperatures were found for those current levels which result in conductor temperatures lower than that at which gross melting of the Tefzel insulation occurs, i.e. 350*C*.
For those current levels which resulted in the temperature of the energized conductors exceeding 350*C, the analyses were terminated when the conductors reached 350*C. The
. tests demonstrated that at this temperature the f
insulation experienced gross melting. The results of these analyses provided answers to the first two questions. The maximum flex surface temperature occurs between 30 and 40 amperes, at the current level that results in a steady-state conductor temperature of 350*C. This is the temperature at which gross melting 4
of the Tefsel insulation occurs.
Analyses were then performed for a vertical, S/8-inch flex, which is the worst case by virtue of the smallest convective surface area and smallest natural convective film coefficient.
In addition, no axial heat flow was modelled, which corresponds to an infinite length of flex. The results of this analysis gave a maximum flex surface temperature of 211*C at 29 asperes.
i Although the manufacturer's stated melting point of Tefzel insulation is 270*C, a conductor temperature higher than 270*C is required to raise the outer surface of the cable jacket to 270*C.
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RESULTS REPORT 1
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-ISAP 1.b.2 (Cont'd)
'5.0_ DISCUSSION OF RESULTS (Cont'd)-
.In lieu of data regarding the temperature of a ' cable one inch away from an adjacent SERVICAIR flex, the unfaulted, exposed cable was assumed to be at the same
=
_ temperature as the surface of the flex containing the faulted circuits. This is a conservative approach.
The flex temperature of 211*C is less than the melting point of Tefzel insulation (270*C). Nonetheless, further study was performed to ensure that the cable would not be degraded due to the elevated temperature.
The manufacturer provides data that Tefzel has a qualified life of 1500-2000 hours at 205'C. This allows approximately two months for the operator to detect and correct the malfunction resulting in the overloaded circuit before the Tefzel qualified life is expended. The following points also provide assurance that a faulted circuit in SERVICAIR flex will not result in damage to's cable one inch away:
U-1)
The temperature of 211*C is for the surface of the flex containing the faulted circuits.
The temperature of c cable one inch from the flex with the faulted circuits would be lower.
2)
These analyses assume that the overload current will not be interrupted by protective devices. In reality, the majority of the instrumentation and control circuits in the control boards and vertical ventilation panels contain protective devices rated at 20
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asperes or less. The 20-ampere protective devices would open the circuit at a current of 29 amperes within one hour. Protective devices rated below 20 amperes would open the circuit at a current of 29 asperes even faster. The remaining instrumentation and control circuits are protected by fuses rated at 30 amperes. An evaluation of these circuits has shown either that components in the circuit other than the protective devices, such as the switchgear trip and close coils, would interrupt a 30-ampere current within one hour or that the circuit
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current would be limited to low current levels by the resistors in series with the light circuits.
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RESULTS REPORT' kl ISAP I.b.2 (Cont'.d) 4
.5.0 ' DISCUSSION-OF RESULTS (Cont'd) 3)
The tests and analyses assumed that four conductors carried the faulted current, i.e.
two complete circuits are assumed to
^
malfunction simultaneously.' If a single circuit.were to fail, the current level required to raise the flex temperature over 205'C is.above 40 amperes. At this current level,; fuses, which are the only 30-ampere protective devices used, would open the circuit within one hour.
The conclusion drawn from the testing and analyses is that, for the control and instrumentation circuits in the con' trol boards and vertical ventilation panels, SERVICAIR flex containing a faulted. Tefsel insulated cable will not cause damage to a Tefsel cable one inch away. Therefore, it was concluded that SERVICAIR flex
-m meats the IEEE 384-1974 definition of a barrier when h
both cables are Tefsel-insulated.
V The reverse situation of a faulted, exposed cable one inch from a SERVICAIR flex containing a redundant cable was inferred from the testing performed. The test results show that the temperature increase above ambient temperature for a conductor one inch above the flex ranged from 28 to 38 percent of the temperature increase above ambient for the SERVICAIR flex. This indicates that heat is being rapidly dissipated by the convective currents in the air.
For the untested case of an exposed, overloaded cable one inch below a SERVICAIR flex, the cable could reach a temperature as high as the melting temperature of Tefsel (350'C) versus the SERVICAIR flex temperature of 149'C from the tests. Using the highest test ratio of the temperature increase of the conductor above the flex to the temperature increase of the flex itself, a flex one inch away from an overloaded cable would be approximately 148'C.
Since the exposed cable would have a higher temperature than the SERVICAIR flex in the test, the air flow would be more turbulent and increesed air mixing would occur. Therefore, the use of the temperature ratio from the test data is O
conservative. Since this conservatively-calculated, flex temperature is of the same magnitude as the flex
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Page 23 of 39, RESULTS REPORT ISAP I.b.2.
(Cont'd)
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5.0 DISCUSSION OF RESULTS (Cont'd) test' temperature, the case of the faulted circuits in the flex, i.e., the case tested and analyzed, will envelope the reverse case of exposed, faulted conductorc below SERVICAIR flex.
5.3.2 Circuit Evaluation for Non-Tefzel Cables Concurrent with the testing program, an evaluation of the control board and vertical ventilation panel circuits was performed by Gibbs & Hill. This evaluation addressed the modular wiring to hand switches as well as other circuits in close proximity to the hand switch wiring. The objective of this evaluation was to determine the maximum current available to the circuits. This information was used to help establish the test conditions for the testine discussed above. Also, from this evaluation, it was determined that six categories of non-Tefzel cables
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were adequately protected by multiple protective
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devices in series or that the maximum faulted current was insufficient to result in heat damage to the subject cables or adjacent cables. These six categories are:
1)
Annunciator lampbox cables, 2)
Safety System Inoperable Indication (SSII) lampbox and field input logic cables, 3)
Power cords from receptacle strips on control wireways to devices such as instrument recorders, 4)
Sound-powered telephone cables, 5)
Coaxial video CRT cables, and 6)
Fire detection cables.
An evaluation of the annunciator (category 1), SSII (category 2), and the power cords from receptacle strips (category 3) demonstrated that a single failure of protective devices in these circuits would not result in sufficient energy to compromise the integrity g
of adjacent safety-related wiring or devices. The circuit evaluation determined that the sound-powered
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Page 24 of 39 I' g' RESULTS REPORT
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.ISAP I.b.2
,(Cont'd)
- 5'.0 DISCUSSION OF RESULTS (Cont'd)
(category 4) and coaxial CRT (category 5) circuits, which. operate at_ voice and video signal levels, respectively, pose no inherent hazards.
Fire detection (category 6) cables comprise 24V de, ungrounded
. supervised circuits having a 13.1K-ohn series resistor in the loop that limits the maximum fault current to very small values. Ground detection is also provided
- for the control room fire detectors. Therefore, the separation criteria for Tefzel-insulated cables can be used for these six categories of cables.
This circuit evaluation did not include the 120-volt AC lighting and convenience receptacle wiring. This wiring is considered to be " power" wiring. The separation criteria for the lighting and convenience receptacle wiring were revised to reflect the fact that it is to be considered more stringently than control and instrumentation wiring. Thus, the criteria state 1
b that SERVICAIR flex is not to be used as a barrier ~or V
the 120-volt AC lighting and convenience receptacle wiring. Additional evaluation on a case-by-case basis I
would be required to demonstrate the acceptability of j
SERVICAIR flex as a barrier for these cables.
5.4 Final Separatio'n Criteria l
The final separation criteria within electrical panels for redundant control and instrumentation cables, one of which is enclosed in SERVICAIR flex, are given in Detail 61F of DCA 21446, Revision 1, to Drawing 2323-El-1702-02, " Cable and Raceway Separation Typical Details." The final separation criteria allow an exposed cable to be one inch from a redundant cable in SERVICAIR flex when each cable is either Tefsel or is a circuit in one of the six categories of non-Tefsel cables discussed in Section 5.3.2.
Furthermore, an exposed cable can be one inch from a redt... dant cable in flex when one of the cables is a non-Tafzel Class IE cable, provided that the other cable is a non-Class 1E cable which is either Tefrel-insulated or non-Tefsel but power-limited (cables discussed in Section 5.3.2).
This is a logical extension of the interpretation of the separation criteria, which is only to protect Class 1E circuits.
For all other cables, which were neither tested nor analyzed due to their limited use, a minimum six-inch separation is required, i.e.,
Ox the separation given in IEEE 384-1974 (Paragraph 5.6.2) for redundant, exposed cables in electrical panels. These criteria are summarized in Table 2 of this report.
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1 Page 25 of 39 RESULTS REPORT ISAP I.b.2 (Cont'd) 5.0 DISCUSSION OF RESULTS (Cont'd) 5.5 Investigations / Inspections / Examinations The second object:ve of this action plan was to reinspect all panels which contain redundant cables that could violate the final separation criteria for SERVICAIR flex to exposed cable.
This program involved three distinct activities:
1)
Preliminary third-party investigations of the control boards and vertical ventilation panels using preliminary, conservative separation guidelines, 2)
Reinspection of the control boards and vertical ventilation panels by TUGCC to the final separation criteria, and
- 3) A third-party examination of multi-train panels to identify all other uses of SERVICAIR flex.
5.5.1 Preliminary Investigations Prior to the completion of the testing and analyses described above, a CPRT third-party inspection of the Unit I control boards and vertical ventilation panels was performed.
Since the majority of SERVICAIR flex is located in the control room control boards and vertical ventilation panels, the third-party QC inspections were limited to these panels.
This inspection provided an assessment of the extent to which SERVICAIR flex was used as a barrier.
In addition, this investigation was used to determine which additional circuits should be included in the circuit evaluation.
It should oe noted that conservative separation guidelines, specified by Gibbs & Hill and approved by the Electrical Review Team Leader, were used in this investigation. As such, they were more restrictive than the final separation criteria.
Using these more restrictive guidelines ensured that all deviations to the final separation criteria that might exist would be discovered.
This was intended to minimize the need for any subsequent inspections.
s Based on these more restrictive inspection guidelines, the third-party inspectors identified 42 instances of SERVICAIR flex-to-exposed cable separation findings.
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v RESULTS REPORT
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JISAP I.b.2 (Cont'd) 5.0 ; DISCUSSION OF RESULTS (Cont'd).
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5.5.2 TUGC0 Inspections Prior to issuing NCRs for the findings identified by the CPRT third-party, TUGCO validated the findings, using the final separation criteria. For those findings which clearly violated the final separation criteria NCRs were issued. Another group of findings were acceptable when compared to the final separation criteria, since some of the attributes of the final separation criteria were less stringent than those used by.the CPRT third-party. For other findings where the minimum separation distance was reduced by the final criteria, it was difficult to determine from the third-party reports if the less stringent, final criteria were met, since the actual separation distances had not been recorded.
To resolve this issue, the Electrical Review Team
('.
Leader initiated, through the TUGC0 Coordinator, an N
inspection of all third-party findings that did not clearly violate the final separation criteria.
Since the final separation criteria had changed to be more restrictive than the original separation criteria *, it'was decided that a reinspection of the panels be performed concurrently with the above validation of the CPRT third-party findings. Only those separation attributes that were revised to be more restrictive were inspected. For example, the final criteria require a six-inch separation between a cable and flex for cases involving certain non-analyzed, non-Tefsel cables; the original criteria required a one-inch separation. This inspection provided the inspection of record for the control boards and vertical ventilation panels.
The original separation criteria are defined as the criteria in existence prior to this action plan, i.
e., Detail 61 of Drawing 2323-El-1702-02, " Cable and Raceway Separation Typical Details".
Revision 2, not including any outstanding Design Change O
Authorizations (DCAs).
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1 Page 27 of 39 RESULTS_ REPORT ISAP I b.1 (Cont'dj 5.0 DISCUSSION OF RESULTS (Cont'd)
The TUGCO QC inspection tdartified eigh: additional violations of SEPVICAIR flex to exposed cable.
The original 42 findings identified by the CPET third-party inspectors we*.e conpared to the final separation criteria. Of the 42 firdings, 19 of tt.,
findings were acceptable per the final criteria.
Therefore, a total of 23 chird-party findings plus eight noted by the TUGC0 inspectors (total of 31 findings) were ic'antif f ed in the Unit I contrcl boards and vertical ventilation panels. Twenty two of tae 31 findisgs were violations to the original criteria.
The remaining nine viointians were violations of c1'e final criteria only.
'I ne Electrical Review Tean. has reviewed the findings from both the third-party inspection and the TUGC0 inspection and concurs with these conclesiona.
A sammary of these firdings is given below:
Acceptable 19 Vio' ations of original 22 and firal criteria Violations )f firvl 9
criteria only Total CPRT third-par ry and 50 TUGC0 findings TUGC0 is currently performing rework in the conte.1 room control boards and vertical ventilation panels to resolve the outstandine, Nonconfermance Reports issued as a result of d6viations relaten to this action plan and Action Plan I.b.4 When this work is complete, a post-construction inspection wi;l be perforned by TdG%
QC inspectors and overviewed by CPPT *hiru party personnel.
5.5.3 Third-Party Examination of Additi, na.1 Multi-Trair Panels The Electrical P niew Team requested that
"*'JC CO identify all other canel.1 ortside the control room control boards and vertica'. vere 11ation panels that contain SERVICAIR flex.
TUGC0 examined panels
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I Page 28 of 39
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RESULTS REPORT lI ISAP I.b.2 (Cont'd) h
'5.0- DISCUSSION OF RESULTS (Cont'd) purchased to Specification MS-605, which bounds the
~ panels authorized to contain flex per DCA-8830 to Electrical Erection Specification 2323-ES-100. TUGC0 provided a list of six additional panels that contain SERVICAIR flex.
(It was subsequently determined that DCA-9086 to the same specification defines SERVICAIR
(
flex as an acceptable metallic barrier and does not limit its use to any particular typa of panel.)
Subsequent'to this response, the action plan was revised to require the CPRT Electrical Review Team to examine all Unit I and common area electrical panels with two or more trains to identify any additional uses of SERVICAIR flex. Panels other than multi-train panels were not examined since a panel that contains only one train does not require electrical separation; therefore, SERVICAIR flex would not have been used as a barrier.
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\\s. / J The first step of this examination process was to generate a list of electrical panels with two or more trains. To determine this, all Unit I and common electrical panel connection drawings and one-line diagrams were reviewed by the CPRT third-party. This review showed that there are no more than 115 electrical panels with multiple trains, including the l
thirteen control room control boards and vertical ventilation panels. During subsequent investigations l
it was determined that some of these panels contained cables exempt from separation requirements, some panels had been removed, some panels were not multi-train panels, etc. The number of multiple train panels requiring cable separation was ultimately reduced from 115 to 88.
The CPRT Electrical Review Team examined the panels and found three that contained SERVICAIR flex in addition.to the six identified by TUGCO.
For all instances where SERVICAIR flex was used outside the control room control boards and vertical ventilation panels, Nonconformance Reports were written. Since the analyses and testing performed for SERVICAIR flex are applicable only to the control room control boards and vertical ventilation panels, the 3
acceptability of SERVICAIR flex as a barrier elsewhere requires further evaluation by TUGC0 on a case-by-case 3^
basis.
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(Cont'd)_
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~W 5.0 DISCUSSION OF RESULTS (Cont'd)'
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O For those cases where SERVICAIR flex was used as a
'O barrier outside the control boards and vertical ventilation panels, three cases were identified where the'ainimum separation distance between an exposed 6
' cable and SERVICAIR flex had been violated.
bi
.The CPRT Electrical Review Team reviewed and concurred L
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'with the disposition of the NCRs issued for SERVICAIR y
- flex in panels other than the control boards and
' vertical ventilation panels.
a 5.5.4 'NRC-TRT Findings The cables listed in Table 1 of NUREG-0797,' Supplement t
.y 7 (also Table 1 of this report) were found'to be in a
contact with other (train). safety-related conduits by a
NRC-TRT during their inspection. These findings were
. reviewed against the TUGC0 post-construction inspection
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V and third-party inspection. The table in the NUREG does kf g not list.what items these cables are touching, so it is not possible now to correlate these findings with subsequent post-TRT inspection reports. An attempt was made to locate what evidence exists to show that none of these cables still. violate separation criteria.
Post-construction inspection records and Inspection
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Reports dated within the time frame of post-TRT
~
inspection were checked. Also the third-party inspection reports were reviewed.
In these document packages a total of 13 of the 21 cables have separation
^
findings written against them.
As stated above, it cannot be determined if these findings are identical to the TRT's; however, the fact 4
that findings were made shove that TUGC0 QC and the CPRT third-party inspected these cables and found separation violations. As for the remaining eight cables, construction activities in the control boards conducted after the TRT inspection, such as installation of unistrut supports for seismic purposes, s
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are likely to have involved the rerouting of cables and 1
possibly eliminated these eight cases.
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'RESULTS REPORT ISAP I.b.2
,(Cont'd) 5.0 DISCUSSION OF RESULTS (Cont'd)
Finally, it should be noted that two 100% inspections since the TRT inspection have been performed. These provide assurance that the NRC'4' separation findings have either been explicitly addressed and corrected or
-no longer exist due to physical changes in the control boards.- In addition, TUGC0 will perform a
- u post-construction inspection of these panels after all rework has been completed.
5.6 Procedure / Drawing Revisions The primary document detailing separation requirements between I
- redundant electrical-cables used by the Project is Drawing 2323-El-1702-02,'" Cable and Raceway Separation Typical Details." In particular, Detail 61 provides the separation criteria for control and instrumentation circuits within electrical panels.
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As a result of the testing and analyses performed during this
]
action plan, a new detail - Detail 61F - was added to the drawing via DCA 21446, which specifies the minimum separation i
for redundant cables, when one cable is enclosed in SERVICAIR flex.
The applicable QC inspection procedures (QI-QP-11.3-28 and QI-QP-11.3-40) were revised to reference this drawing for separation requirements.
In addition, DCA-8830, which originally revised the Electrical Erection Specification but now also applies to Drawing 2323-El-1702-02, was revised to allow flex in " Reliance
~
Control Board and Vertical Ventilation Panels (MS 605)."
These document changes involving the use of SERVICAIR flex as a barrier were reviewed by the Electrical Review Team Leader.
In addition to reviewing these documents, the Electrical Review Team reviewed the sections of Electrical Erection Specification ES-100 relating to internal wiring separation, as well as the applicable portions of the Brown & Root Construction Procedure 35-1195-EEI-8, " Class 1E and Non-Class IE Cable Terminations."
Suggestions for enhancement of these documents were I l' transmitted to TUGCO. The Project responded to the comments
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and the Electrical Review Team concurs with the proposed actions to revise these documents to resolve the comments.
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1 Paga 31 of 39-t j
!RESULTS REPORT
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LISAP I.b.2
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(Cont'd)
[5.0 ' DISCUSSION OF RESULTS -(Cont'd) -
5.7 - Review of Training
.The Electrical Review Team also reviewed the current program for training of construction and QC personnel.
.C, raft instructors were interviewed to determine the extent and depth l
of the instruction given craft personnel in the area of electrical separation inside panels. The program is comprehensive and includes classroom training on procedures, examinations, and " hands-on" experience. The. Electrical
= Review Team noted that separation criteria are shown on Drawing-2323-El-1702-02, " Cable and Raceway Separation Typical Details," in addition to the Electrical Erection Specification 2323-ES-100. Since the instrue. tors were not receiving controlled copies of changes to the drawing, they were not
^
aware of the changes made to the separation criteria for SERVICAIR. flex..This has since been remedied by having the instructors receive controlled copies of all changes to this
. drawing. Therefore, whenever the drawing is revised or a
[ M[
' design change is made,to the drawing, the instructors will automatically receive these documents.
The Electrical Review Team reviewed the QC Lesson Plan developed for QC Procedure QI-QP-11.3-28.
The Lesson Plan presents the subject of separation inside panels adequately
~
and refers the inspector to Drawing 2323-El-1702-02 for details.
Due to the changes that are currently being incorporated into the procedures, drawing, etc., further training will be required.
5.8 Categorization of Findings 5.8.1 Control Boards and Vertical Ventilation Panels The CPRT third-party inspectors and TUGC0 QC inspectors, during their inspections of the control boards and vertical ventilation panels, identified 31 violations of the final separation criteria for two redundant cables, one cable of which is enclosed in SERVICAIR flex.
Of the 31 violations, 22 were deviations of the criteria in existence when the cables were installed.
O The remaining n'ine deviations were violations of the final criteria developed as a result of this action plan, but were not deviations of the original criteria.
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RESULTS REPORT
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ISAP I.b.2 (Cont'd) 4.,
L5.0; DISCUSSION OF RESULTS (Cont'd)
'5.8.2' Panels Other Than The Control Boards and Vertical
- Ventilation Panels For panels other than the control boards and vertical ventilation panels, the CPRT Electrical Review Team examined all multi-train panels to determine where SERVICAIR flex had been used as a barrier. During this
' examination of multi-train panels, a total of nine panels were found to contain a total of 16 pieces of SERVICAIR flex.
Since.the existence of these pieces of flex is in violation of the final criteria, Nonconformance Reports were issued.
In addition to these nine panels SERVICAIR flex was found in a Reliance-supplied panel, cpi-ECPRLV-17, by third-party QC inspectors performing inspections for Action Plans I.a.2 and I.a.3.
During the process of 7'~'j resolving a separation violation, this flex was removed
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' prior to the Electrical Review Team's examination of multi-train panels. Therefore, the examination of multi-train panels performed for this action plan did
'not identify..any flex in Panel cpi-ECPRLV-17.
These cases of SERVICAIR flex in panels other than the control boards and vertical ventilation panels are addressed in Action Plan I.b.1.
It should be noted, however, that-violations of the original separation criteria for exposed cables and SERVICAIR flex were noted in three of the nine panels.
5.8.3 Observations During the implementation of this action plan, several observations were noted. These observations are discussed in the Results Repcrt for Action Plan I,b.1.
5.9 Safety Significance Evaluation The CPRT third-party inspection and TUGC0 inspection of the Unit I control room control boards and vertical ventilation panels resulted in 31 violations of the final separation criteria for exposed cables and SERVICAIR flex. Three additional findings of exposed cables and SERVICAIR flex were identified in panels other than the control boards and vertical ventilation panels. Of the 34 total findings, nine are not deviations since the installation did not violate the criteria in existence at the time of installation.
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- Page 33 of 39
~
.73,- y RESULTS REPORT
'M ISAP I.b.2 1.-
(Cont'd)
_l5.0 DISCUSSION OF RESULTS _(Cont'd)
. The determination of whether or not these deviations are safety-significant would require an extensive program of testing and analyses of the various different types of cable insulation and circuit functions involved. Rather than perform this type of safety. significance evaluation, the deviations have been categorized as " unclassified deviations".
- As such the deviations will be corrected, a root cause evaluation will be performed, and generic implications will be investigated.
5.10 Root Cause/ Generic Implications
- These deviations represent violations of cable-to-flex separation only. Other similar violations, such as cable-to-H
. cable separation violations and cable-to-wireway separation violations, were also found.
These deviations are addressed
- in Action Plan I.b.4.
Because the deviations identified in this action pl~n are similar to those addressed in Action Plan a
/~) _
I.b.4,:the root cause analysis and generic implications
- y. /
evaluation for all separation de'viations will be reported in the Results Report for Action Plan I.b.4.
The root cause analysis and generic implications evaluation for Action Plan I.b.4 are currently being conducted.
5.11 Corrective Action
)
The corrective actions required for the unclassified i
deviations noted above are for TUGC0 to issue and close out Nonconformance Reports for the deviations. The Electrical Review Team will review the disposition of these NCRs as part of the NCR review performed for Action Plan I.b.4.
The disposition and third-party review of the NCRs issued for those cases where SERVICAIR flex was used outside the control room control boards and vertical ventilation panels have been addressed by the Results Report for Action Plan I.b.1.
The details of the corrective actions associated with the root cause and generic implications of the deviations noted in this action plan are addressed in the Results Report for I.b.4.
A general description of the proposed corrective actiona is 2'
provided in the Results Report for Action Plan I.b.1.
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1 Page 34 of 39 RESULTS REPORT ISAP I.b.2 (Cont'd) 5.0' DISCUSSION OF RESULTS (Cont'd) 5.12 Additional Findings, All additional findings including cable-to-cable and cable-to-wireway separation nonconformances noted during the implementation of this action plan will be addressed in the Results Report for Action Plan I.b.4.
5.13 Unit 2 Multi-Train Panels The inspections and examinations performed under this action plan involved Unit 1 and common area multi-train panels.
Eowever, the corrective action discussed in the Results Report for Action' Plan I.b.1 will also apply to Unit 2.
This corrective action will ensure that the use of SERVICAIR fler meets the final separation criteria developed as a result of this. action plan.
6.0 CONCLUSION
S The actions identified by the NRC in Section 2.0 of this report can be separated into the following three items:
- 1) Reinspect all panels which contain SIRVICAIR flex and exposed
- cables,
- 2) Demonstrate by analysis the acceptability of SERVICAIR flex as a barrier. or provide the necessary separation, and
- 3) Isevise the engineering drawings and related documents to reflect the final separation criteria.
To satisfy Item 1, the Unit I control boards and vertical
~
ventilation panels were reinspected.
In addition, all Unit 1 and common area multi-train panels that require separation of cables were examined to determine if they contain SERVICAIR flex.
Since the criteria have been revised to authorize the use of flex only in the control boards and vertical ventilation panels, Nonconformance Reports were issued whenever SERVICAIR flex was used in panels other than the control boards and vertical ventilation panels. For Unit 2, the TUGC0 program described in the Results Report for Action Plan I.b.1 will ensure that field installations meet the final separation criteria for SERVICAIR flex.
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1 Page 35 of 39
'n RESULTS REPORT e
- \\
).
ISAP I.b.2 (Cont'd)
6.0 CONCLUSION
S (Cont'd)
The findings noted by the NRC-TRT are deviations from the original, as well as final, separation criteria. The aforementioned inspections, in conjunction with the completion of ongoing activities, will ensure that all deviations to the final separation criteria for exposed cables to SERVICAIR flex have been identified and corrected.
To satisfy Item 2, analyses and testing were performed to demonstrate that SERVICAIR flex in combination with a one-inch gap from an exposed cable is an acceptable barrier for the majority of the circuits in the control room control boards and vertical
-ventilation panels.
For the remaining circuits, a six-inch separation is specified, which is the same separation required for two exposed cables.
To satisfy Item 3, the final separation criteria are being incorporated into the appropriate project documents, (p)
These actions, in conjunction with the completion of ongoing
'~
activities, will ensure that all concerns regarding separation of redundant cables, one of which is enclosed in SERVICAIR flex, are resolved.
7.0 ONGOING ACTIVITIES The NCRs issued for the control room control boards and vertical ventilation panels as a result of deviations related to this action plan as well as Action Plan I.b.4 have not yet been completely resolved. After the NCRs are closed, TUGC0 will perform a post-construction inspection of these panels, which will include verification of adequate separation between exposed cables and SERVICAIR flex. This inspection will be overviewed by the CPRT third-party.
Upon the completion of these ongoing activities, a Supplemental Report will be issued; this supplement will provide the results of the activities described above.
8.0 ACTION TO PRECLUDE OCCURRENCE IN THE FUTURE The corrective action described in the Results Report for Action Plan I.b.1 will ensure that separation inside multi-train panels
\\
will be established and maintained.
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1 Paga 36 of 39
't RESULTS REPORT
_j ISAP I.b.2 (Cont'd)
Table 1*
Safety or Nonsafety-Related Cables in Contact with Other Safety-Related Conduits in Control Room Panels 1.
Control Panel CP1-EC-PRCB-02: Containment Spray System Cable No.
Train Related Instrument EG139373 B (green)
Undetermined E0139010 A (orange)
Undetermined 2.
Control Panel CPI-EC-PRCB-07: Reactor Control System Cable No.
Train Related Instrument EG139383**
B (green)
Reactor manual trip switch i
E0139311 A (orange)
Undetermined
'[
') L E0139310 A (orange)
Unletermined
\\ '-
EG139348 B (green)
Undetermined 3.
Control Panel CP1-EC-PRCB-06: Chemical & Volume Confrol System Cable No.
Train Related Instrument EG139335 B (green)
LCV-112C E0139301 A (orange)
Undetermined E0139305 A (orange)
LCV-112B NK139605 Nonsafety CSALB-6AB (in bundle) 4.
Control Panel CPI-EC-PRCB-09: Auxiliary Feedwater Control System Cable No.
Train Related Instrument E0139753 A (orange)
FK-2453A E0139754 A (orange)
FK-2453B EG139756 B (green)
FK-2454A EG139288 B (green)
FK-2454B EG145780 B (green)
'A
(_,)
From NUREG-0797, Supplement 7 Table 1 Pages J-39-40.
The correct number is EG139352.
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1 Pags -37 of 39 i
' ' '(
RESULTS REPORT J
ISAP 1.b.2 i
(Cont'd)
Table 1 (Cont'd) s..
Cable No.
. Train Related Instrument
~ EG145781:
B (green)
FK-2460A A0138622~
A (orange HS-2452G-H Assoc.)'
NK139647 Nonsafety HS-2383 5.
-Control Panal~ CPI-EC-PRCB-08: Feedwater Control Cable No.
Train Related Instrument EG140309 B (green)'
PK-2324 EG139757 B (green)
PK-2328 NK13957 Nonsafety HS-211A A-V
.. ~ -. - - - - -.. -. - - -
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,y
'/
RESULTS REPORT x_/
ISAP I.b.2 (Cont'd)
Table 2 Final' Separation Criteria for SERVICAIR flex to cable inside the Control Boards and Vertical Ventilation Panels A
Tefzel or Analyzed Non-Analyzed Non-Tefzel Non-Tefzel Class IE Non-Class IE Class 1E Non-Class 1E Tefsel or.-
Class 1E 1"
1" 6"
6"
. Analyzed Not-Tefsel Non-Class 1E 1"
X 1"
X Q
Class IE 6"
1" 6"
6" Q
Non-analyzed Non-Tefsel Non-Class 1E 6"
X 6"
X X -- No Separation Required (Circuits are not redundant) i
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1 Page 39 of 39 RESULTS REPORT ISAP I.b.2 (Cont'd)
Chronology of Major Activities Related to Action Plan I.b.2 July-September 1984 The NRC-TRT conducted onsite inspections, including a review of the Unit 1 control room control boards.
October 1984 The initial version of Action Plan I.b.2 was issued.
November 1984 -
TUGC0 performed a post-construction January 1985 inspection of the Unit I control boards and vertical ventilation panels.
January 1985 A draft of the circuit evaluation was prepared.
February-April 1985 An inspection of the Unit 1 control boards
/~'s and vertical ventilation panels was performed
(
by the CPRT third-party inspectors.
March 1985 Short circuit and heat transfer tests of SERVICAIR flex were performed.
July 1985 DCA 21446 to Drawing 2323-El-1702-02, " Cable and Raceway Separation Typical Details," was issued. This DCA contained new criteria for SERVICAIR flex in the control boards and vertical ventilation panels.
July 1985 Revision 1 of the circuit evaluation was issued.
October 1985 TUGC0 performed a reinspection of the Unit 1 control boards and vertical ventilation l
panels using the final separation criteria.
March 1986 Revision 0 of the computer analysis of SERVICAIR flex was issued.
January, May, and The CPRT Electrical Review Team examined Unit June 1986 1 and common area multi-train panels to determine where SERVICAIR flex had been used.
(
(Future)
TUGC0 will perform a final inspection of the Unit I control boards and vertical ventilation panels using the final separation criteria. This inspection will be overviewed by the CPRT third-party.