ML20052H933
| ML20052H933 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/14/1982 |
| From: | Udy A EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20052H929 | List: |
| References | |
| CON-FIN-A-6425, TASK-08-04, TASK-8-4, TASK-RR EGG-EA-5847, NUDOCS 8205240207 | |
| Download: ML20052H933 (11) | |
Text
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_muuava s EGG-EA-5847 April 1982 SYSTEMATIC EVALUATION PROGRAM, TOPIC VIII-4, ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT, HADDAM NECK NUCLEAR STATION
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o A. C. Udy-U.S. Department of Energy Idaho Operations Office
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4kg This is an informal report intended for use as a preliminary or working document Prepared for the f,
U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-761D01570 FIN No. A6425 Q
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E traho lac p OHed (G4G 39e (Hsv 03 823 INTERIM REPORT Accession No.
EGG-EA-5847 Report No.
Crntract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
Systematic Evaluation Program, Topic VIII-4, Electrical Penetrations of Reactor Containment, Haddam Neck Nuclear Station Type of Document:
Informal Report Author (s):
A. C. Udy Dite of Document:
April 1982 R2sponsible NRC Individual and NRC Office or Division:
Ray F. Scholl, Jr., Division of Licensing This document was prepared primarily for preliminary or internal use. it has not received full review and approval. Since there may De substantive changes, this document should not be considered final.
EG&G Idaho. Inc.
Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07-761D01570 NRC FIN No.
A6425 INTERIM REPORT
0080J o
SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT HADDAM NECK NUCLEAR STATION Docket No. 50-213 April 1982 A. C. Udy.
EG&G Idaho, Inc.
9 4/14/82
ABSTRACT This SEP technical evaluation, for the Haddam Neck Nuclear Station, reviews the capability of the overcurrent protection devices to protect the I
electrical penetrations of the reactor containment for postulated fault conditions concurrent with an accident condition.
FOREWORD This report is supplied as part of the " Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)"
being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc.,
Reliability & Statistics Branch.
The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05, FIN A6425.
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CONTENTS
1.0 INTRODUCTION
1 2.0 CRITERIA........................................................
1 3.0 DISCUSSION AND EVALUATION.......................................
2 3.1 Typical Low Voltage (0-1000 VAC) Penetration..............
3 s
3.1.1 Low Voltage Penetration Evaluation................
3
. 3.2 Typical Medium Voltage (>1000 VAC) Penetration............
4 3.2.1 Medium Voltage Penetration Evaluation.............
4 3.3 Typical Direct Current Penetration........................
4 3.3.1 Direct Current Penetration Evaluation.............
5 4.0
SUMMARY
S
5.0 REFERENCES
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SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT HADDAM NECK NUCLEAR STATION
1.0 INTRODUCTION
This review is part of the Systematic Evaluation Program (SEP), Topic e
VIII-4. Cognecticut Yankee Atomic Power Company (CYAPCO) has provided information describing typical penetrations, typical in-containment loads, and fault currents. As new penetrations have been installed, CYAPC0 has provided information on these penetrations.
The objective of this review is to determine the capability of the overcurrent protective devices to prevent exceeding the design rating of the electrical penetrations through the reactor containment during short circuit conditions at loss-of-coolant accident (LOCA) temperatures.
General Design Criterion 50, " Containment Design Basis" of Appendix A,
" General Design Criteria for Nuclear Power Plants" to 10 CFR Part 50 requires that penetrations be designed so that the containment structure can, without exceeding the design lea' age rate, accommodate the calculated pressure, temperature, and other environmental conditions resulting from any loss-of-coolant accident.
IEEE Standard 317, " Electric Penetration Assemblies in Containment Structures for Nuclear Power Generating Stations", as augmented by Regula-tory Guide 1.63, provides a basis of electrical penetrations acceptable to the staff.
Specifically, this review will examine the protection of typical elec-trical penetrations in the containment structure to determine the ability of the protective devices to clear the circuit during a short circuit con-dition prior to exceeding the containment electrical penetration test or design ratings under LOCA temperatures.
2.0 CRITERIA IEEE Standard 317, " Electric Penetration Assemblies in Containment Structures for Nuclear Power Generating Stations" as supplemented by Nuclear Regulatory Commission Regulatory Guide 1.63, " Electric Penetration Assemblies in Containment Structures for Light-Water-Cooled Nuclear Power Plants" provides the basis acceptable to the NRC staff. The following criteria are used in this report to determine compliance with current licensing requirements:
(1) IEEE Standard 317, Paragraph 4.2.4 - "The rated short circuit s
current and duration shall be the maximum short circuit current in amperes that the conductors of a circuit can carry for a specified duration (based on the operating time of the primary overcurrent protective device or apparatus of the circuit) fol-lowing continuous operation at rated continuous current without 1
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the temperature of the conductors exceeding their short-circuit design limit with all other conductors in the assembly carrying their rateo continuous current under the specified normal environmental canditions."
This paragraph is aagmented by Regulatory Guide 1.63, Para-graph C "The electric penetration assembly should be designed to withstand, without' loss of mechanical integrity, the maxinum possible fault current versus time conditions that could occur given single random f ailures of circuit overload protection devices."
(2)
IEEE Standard 317, Paragraph 4.2.5 - "The rated maximum duration of rated short circuit current shall be the maximum time that the conductors of a circuit can carry rated short circuit current based on the operating time of the backup protective device or apparatus, during which the electrical integrity may be lost, but for which the penetration assembly shall maintain containment integrity."
3.0 DISCUSSION AND EVALUATION In this evaluation, the results of typical containment penetrations being at LOCA temperatures concurrent with a random failure of the circuit protective devices will be analyzed.
CYAPC0 has provided information on the newly installed penetrations.2 All were manuf actured by Conax Corporation, which also performed tests and reported to CYAPCO the test qualification data.
In supplying the value of the maximum short circuit current available bolc),CYAPC0suppliedvaluesforathree-phase (onathree-phasesystem)
(I ted fault, this type of fault being able to supply the most heat into the penetration. The I value includes in the symmetrical AC component sc contributions by other connecteo induction motors.
Under accident conditions, a peak containment temperature of 267*F (130.5*C) is expected.3 The following formula was used to determine the time allowed for a short circuit before the penetration temperature would exceed its limiting value.9 2
'T2 + 234'
.g g
t = 0.0297 log Tj + 234, 2
T + 234 t = 0.02 7 A I 9 T + 234 (Formula 1) sc 2
where Time allowed for the short circuit in seconds t
=
Short circuit current in amperes I
=
sc Conductor area in circular mils A
=
Tj Maximum operating temperature (130.5'C, LOCA condition;
=
Maximum short circuit temperature (limiting factor for a e
T2
=
given penetration determined from qualification test data).
This formula is based upon the heating effect of the short circuit current on the conductors, and assumes that the heating of the penetration seal is uniform with the penetration conductors.
In this report, a pre-f ault penetration conductor temperature that is equal to the peak LOCA containment atmosphere temperature is assigned, regardless of the outer seal that may be at a lower initial temperature. This simplifies the model, while accounting for an elevated conductor temperature caused by a pre-existing current flow and an above normal ambient temperature.
3.1 Typical Low Voltage (0-1000 VAC) Penetration. CYAPC0 has pro-vided information on a penetration that is a part of a typical 480 VAC motor operated valve circuit. This penetration has ten feedthru ports, and The presentlyusesfiveofthese,withatotalof95#10AgGconductors.
current capacity is rated at 20 amperes per conductor.
The test data was extrapolated by Conax Corporation jo give a conductor temperature limit of 426*C for short circuit conditions.
The maximum I available for this circuit is 750 amperes rms sym-metrical. Itiscaiculatedthat,withthe426Ctemperaturelimitofthe s
penetration conductors, this short circuit current can be carried by the penetration for 1.47 second before the temperature limit of the penetration conductors is exceeded, when the initial temperature is 130.5"C (peak LOCA in-containment temperature). No credit for heat transfer lag from the conductor to the penetration is taken.
The primary 40 ampere circuit breaker will clear this fault in
.65 second. At all levels of current greater than the rated continuous current of the penetration conductors, the primary circuit breaker will clear the f ault before the conductor temperature exceeds the temperature limit of the penetration. Since all in-containment components of this particulgr circuit are tg be environmentally qualified for Class lE service, NRC position 2 can be applied. This position requires only i
l a single Class lE circuit breaker for penetration protection, when all circuit components served by that penetration circuit inside of containment i
are qualified to Class lE requirements.
3.1.1 Low Voltage Penetration Evaluation. With an initial pene-tration temperature of 130.5"C (the LOC fcontainment temperature),
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this low voltage penetration is design:d and utilized within the criteria described in Section 2.0 of this report.
3.2 Typical Medium Voltage (>1000 VAC) Penetration. CYAPC0 has provided information on a penetration used to power the reactor coolant pump, P-17-2.
Each penet tion consists of three 1500 MCM conductors that ditions,to255*Cgtion.ga These have been tested for short circuit con-have "Kerite" insu The maximum I available at the penetration is 21,625 rms symmetri-cal amperes. CYAPb did not supply the asymmetrical fault current, saying it is insignificant.
It is calculated that 18.2 seconds elapse after this f ault occurs at a penetration temperature of 130.5*C (LOCA containment temperature) before the conductors exceed the tested temperature limit.
The instantaneous trip f ault clearing time of the primary air circuit breaker (ACB) is approximately.17 second per IEEE Standard 242-1975, Table 33, regardless of the asymmetrical f ault current. This circuit breaker can also be tripped by differential current relays. The secondary ACB will clear the f ault current within 2.03 seconds crediting only the synmetrical component. At all levels of current greater than the rated continuous current of the penetration conductors, both circuit protective devices clear the fault before the conductor temperature exceeds the temperature limit of the penetration.
3.2.1 Medium Voltage Penetration Evaluation. With an initial penetration temperature of 130.5 C (the LOCA containment tempera-ture), this medium voltage penetration is designed and utilized within the criteria described in Section 2.0 of this report.
It can be seen that the asymmetrical component is, indeed, insignificant. Using an asymmetrical / symmetrical current ratio of 1.6, the asymmetrical component, lasging less,than three heat the penetration conductors versus 9.5 x 10[ mperes -second cycles, supplies no more than 8.42 x 10 ampere second to 2
a over the entire clearing time of the secondary circuit breaker.
Thus, the asymmetrical heat generated would be less than 0.9% of the total heat generated in the penetration.
3.3 Typical Direct Current Penetration. CYAPC0 has provided infor-l mation for the penetration used with a 125 VDC stationary gripper coil on l
control rod #24. The penetration construction is identical to that discus-3 l
sed in Section 3.1 except that there are ten feedthru ports, each with nine at 35 amperes.grs (a total of 90 conductors).
- 6 AWG conduct The current capacity is rated The test data also sh of 372*C for short circuit conditions.gws a conductor temperature limit l
The maximum I c available for this circuit is 890 amperes DC.
It is s
calculated that the maximum I can be carried by this penetration for sc 5.70 seconds before the conductor temperature reaches its limiting temper-ature.
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The fuse curves supplied by CYAPCO show that both the primary fuse and the secondary f use will clear this f ault in less than.01 second. At all current levels above the 30 ampere rating of the fuse, the clearing time is ddeQuale to prevent damage to the penetration seal.
3.3.1 Direct Current Penetration Evaluation. With an initial penetration temperature of 130.5*C (the LOCA containment tempera-ture), this direct current penetration is designed and utilized within the criteria described in Section 2.0 of this report.
4.0
SUMMARY
This evaluation looks at the capability of the circuit protective 3
devices to prevent exceeding the design ratings of the selected penetra-tions in the event of (a) a LOCA event, (b) a f ault current through the penetration and simultaneously, (c) a random failure of the circuit protec-tive devices to clear the f ault. The environmental qualification tests of the penetrations is the subject of SEP Topic III-12.
This assessment neglects any heat transfer from the penetration to the containment liner. To account for rated current in the penetration con-doctors, an initial penetration temperature equal to the peak LOCA in-containment temperature was assigned throughout the penetration.
With a LOCA environment inside containment, all sampled penetrations are designed and utilized within the criteria of Section 2.0 of this report, which assumes a short circuit and random f ailure of circuit protective devices.
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5.0 REFERENCES
1.
CYAPC0 letter, W. G. Counsil to Director of Nuclear Reactor Regulation, NRC, " Systematic Evaluation Program (SEP), Topic VIII-4, Electrical Penetrations," March 23, 1979.
CYAPCO letter, W. G. Counsil to Director of Nuclear Reactor Regula-2.
tion, NRC, "SEP Topic VIII-4, Electrical Penetrations," September 30, 1981, A01811.
3.
CYAPC0 letter, W. G. Counsil to Director of Nuclear Reactor Regulation, NRC, SEP Topic Vill-4, Electrical Penetrations of Reactor Containment," March 22, 1982, A02190.
4.
NRC letter, D. M. Crutchfield to W. G. Counsil, CYAPCO, "SEP Topic Vill-4," December 23, 1981.
General Design Criterion 16. " Containment Design" of Appendix A, " Gen-5.
eral Design Criteria of Nuclear Power Plants," 10 CFR Part 50,
" Domestic Licensing of Production and Utilization Facilities."
Nuclear Regulatory Commission Standard Review Plan, Section 8.3.1, "AC 6.
Power Systems (Onsite)."
5
7.
Regulatory Guide 1.63, Revision 2 " Electrical Penetration Assemblies in Containment Structures for Light-Water-Cooled Nuclear Power Plants."
8.
IEEE Standard 317-1976, "lEEE Standard for Electric Penetration Assem-blies in Containment Structures for Nuclear Power Generating Stations."
9.
IPCEA Publication P-32-382, "Short Circuit Characteristics of Insulated Cable."
- 10. IEEE Stanoard 242-1975, "IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems."
- 11. " Design Qualification Report of Low Voltage Power and Control Penetra-tion Assemblies for Connecticut Yankee Nuclear Power Station for North-east Utilities Service Company," IPS-434.1, Revision 1, May 23,1980, Conax Corporation.
- 12. " Design Qualification Report of Medium Voltage Power Penetration Assemblies for Connecticut Yankee Nuclear Power Station for Northeast Utilities Service Company," IPS-434.3, Revision B, August 12, 1980, Conax Corporation.
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