ML20031F048
| ML20031F048 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 09/30/1981 |
| From: | Udy A EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6425, TASK-08-04, TASK-8-4, TASK-RR EGG-EA-5565, EGG-EA-5565-01, EGG-EA-5565-1, NUDOCS 8110190099 | |
| Download: ML20031F048 (16) | |
Text
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SO ~EW EGG-EA-5565 SEPTEMBER 1981 90R
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SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-4, Afg(
ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT, y,g R. E. GINNA NUCLEAR STATION, UNIT N0. I ff NTC 1esearci and Tec;inica i
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This is an informal report intended for use as a preliminary or working document i
l-Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 g
FIN No. A6425 g g g g,,,n, 8110190099 810930
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FORW EGAG 398 (Rev 11 M INTERIM REPORT Accession No.
Report No. EGG-EA-5565 Contract 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, R. E. Ginna Nuclear Station, Unit No. 1 Type of Document:
Informal Report
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- N RC Researci anc "ecanica A. C. Udy Assistance Report Date of Document:
September 1981 Responsible 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 be substantive changes, this document should not be considered final.
EG&G Idaho, Inc.
i Idaho Falls, Idsho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE AC07 761D01570 l
NRC FIN No. __ A6425 l,
INTERIM REPORT l
1
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SYSTEMATIC EVALVATION PROGRAM TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT R.E. GINNA NUCLEAR STATION, UNIT NO. 1 Docket No. 50-244 September 1981 A. C. Udy Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.
I NRC Researc'a andt Te Assistance Report i
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9-9-81
ABSTRACT This SEP. technical evaluation, for the R. E. Ginna Nuclear Statico, Unit No. I reviews the capaoility of the overcurrent protection devices to protect the. electrical penetrations of the reactor containnent for postu-lated 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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t CON TENTS 1.0 I N TR O D UC T I O N....................................................
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C.0 CRITERIA........................................................
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a.0 DISCUSSION AND EVALUATION.......................................
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3.1 Typical Low Voltage (0-1000 VAC) Penetrations.............
5 3.1.1 Penetration Number AE-6............................
5 3.1.2 Penetration Number AE-5............................
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3.1.3 Penetration Number CE-21...........................
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3.1.4 Low Voltage Penetration Evaluation.................
6 3.2 Typical Medium Voltage (21000 VAC) Penetrations...........
7 3.2.1 Medium Voltage Penetration Evaluation..............
7 3.3 Typical Direct Current Penetrations.......................
8 3.3.1 Pene trat ion Number CE -18...........................
8 3.3.2 Penetration Number CE-17'...........................
8 3.3.3 Penetration Number CE-23...........................
9 3
3.3.4 Direct Current Penetration Evalutation..............
9 3.4 Other Penatrations........................................
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4.
SUMMARY
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REFERENCES......................................................
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SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT R.E. GINNA NUCLEAR. STATION, UNIT N0. 1
1.0 INTRODUCTION
This review is part of the Systematic Evaluation Program (SEP), Topic VIII-4. The evaluation provided by Rochester Gas and Electric (RGE)I has demonstrated the adequacy of the penetrations and the circuit protective 2
devices during normal operation. A letter of July 21, 1980 provides additional information on the penetration designs.
The oojective of this review is to determine tne capability of the overcurrent protecti+/e devices to prevent exceeding the design rating of the electrical penetrations through the reactor containment during snort circuit conditions at 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 tnat penetrations be designed so-that the containment structure can, without exceeding the design leakage rate, accommodate the calculated pressure, temperature, and other environmental conditions resulting from any loss-of-coolant accident.(LOCA).
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 )rotection of typical elec-trical penetrations in the containment structure to oetermine the' ability of the protective devices to clear tne circuit juring a~short circuit con-dition prior to exceeding the containment elecf.rical penetration. test or design ratings with initial assumed LOCA temperatures.
1 1
t 2.0 CRITERTA IEEE Standard 317, " Electric Penetration Assemblies in Containme.,t Structures for Nuclear Power Generating Stations" as supplemented by Nuclear Regulatory Commission Regulatory Guide 1.63, " Electric Penetration Assem-blies in Containment Structures for Light-Water-Cooled Nuclear Power Plants" provides the basis acceptable to the NRC staff.
Tne following criteria are used in this report to determine compliance with current licensing require-ments:
1.
IEEE Standard 317, Paragraph 4.2.4- "The rated short circuit 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 tne operating time of the primary overcurrent protective device or apparatus of the circuit) following continuous operation at rated continuous current without the tem-perature of the conductors exceeding their short circuit design limit with all other conductors in the assembly carrying their rated continuous current under the speci-fied normal environmental conditions."
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Tnis paragrapn is augmented by Regulatory Guide 1.63, Paragraph C "The electric penetration assembly snould be designed to withstand, without loss of mechanical integrity, tne maximum possible fault current versus time conditions tnat could occur given single random failures of circuit overload protection devices."
2.
-IEEE_ Standard 317, Paragrapn 4.2.5- "The rated maximum duration of rated short circuit current snall be the maximum time that the conductors of a circuit can carry rated snort circuit current based on the operating time of the backup protective device or apparatus, during which tne electrical integrity may be lost, but for which the penetration assembly shall maintain contain-ment integrity."
i Additional clarification of these criteria was provided to RGE on Marcn 30,'1981.3 I
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3.0 DISCUSSION AND EVALUATION In this evaluation, the results of typical cantainment penetrations being at LOCA temperatures concurrent with a random failure of the circuit protective devices will be analyzed.
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l RGE has provided information,2 on typical penetrations. Additional 4
material, submitted as a result of this review was provided on June 9, 1981 and July 14, 1981.5 All penetrations but one were manufactured by Crouse-Hinds, who no longer makes these penetrations. Crouse Hinds supplied RGE with test data, where available, and calculated data with a 10x safety factor where test data was not available.
RGE has established that before damage to tne hermetic seal of the penetration occurs, melting of tne solder in the hermetic seal of the pene-trations must occur (361 F, 180*C).
A silver braze is used for penetrations CE-21, CE-25 and CE-27 instead of solder (1100*F, 600"C). This temperature is used because it is tne lowest temperature tnat affects the penetration seal. Otner materials, while affecting the strain relief of the penetration at lower temperatures, do not affect the hermetic seal.
Tne limiting temperature is determined by the analysis of the construction of the penetrations rather than testing. Tne Ginna 1 Technical Specifica-tion allows for initial steady state temperatures of the penetration envi-ronment up to 120*F (49 C).
Under accident conditions, a peak temperature of 285 F (140'C) is expected.
In those penetrations with co'iductors larger than #2 copper, the limit was not heat input but mechanical forces generated by electromagnetic coup-ling, and the limits put on these was determined by tests, with no mechani-cal failure of the penetration. Smaller penetration conductors are not subject to failure oy mechanical forces when used within their maximum curre-t rating.
RGE also used the Insulated Power Cable Engineers Association publica-tion, P-32-382, entitlea "Short Circuit Characteristics of Insulated Cable" 3
to determine separate limiting factors on the conductors of the penetration.
Where tnese figures were more conservative tnan tne Crouse-Hind figures, they were used instead.
In supplying the value of the maximum short circuit current available (1sc), RGE supplied values for a thre.e-phase (on a,tnree-pnase system) bolted f ault; this type Deing able to supply the most neat into the penetra-tion.
Tne I va u supplied by E tahs bon ne symeWal AC compon-sc ent and the peak DC offset component.
In the RGE analysis, the Isc ***
held to the maximum value for all phases when only one phase can have the full initial offset, and despite the fact that the DC component decays.
This provides an additional safety factor in tueir calculations. RGE did not assume tnat all other penetration conductors were carrying their maximum rated current, but applied the normal operating current.
b Tne following fonnula was used to determine the time allowed for a short-circuit before tne penetration conductor temperature would exceed the melting point of solder.
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e This is based upon the neating effect of the snort circuit current on the conductors.
It should be noted that tne short circuit temperature-time limits of I
the conductors in this report vary from the values calculated by RGt even tnough the same methods are used. RGE has utilized an initial temper-ature of 40'C wnile tnis review uses an initial temperature of 140*C (LOCA condition) for the penetration. A pre-fault penetration conductor temper-ature equal to the peak LOCA containment atmosphere temperature is assigned, thus simplifying while accounting for an elevated conductor temperature caused by pre-existing current flow and above-normal ambient temperature.
3.1 Typical Low Voltage (0-1000 VAC) Penetrations.- RGE has provided information on three typical low-voltage AC penetrations.I 3.1.1 Penetration Number AE-6.
This penetration has #2 AWG con-ductors and was type-tested to 37,400 amperes for 3 cycles by the manufac-turer, Crouse-Hinds. Tne I available on the identified 480-V circuit sc is 9600 amperes. Using Formula 1, tnis currant can be carried for 0.06 sec-ond oefore the penetration conductor temperature exceeds the melting point of solder while under a LOCA environment. The primary circuit breaker responds within this tinie (.018 second).
The secondary circuit breaker does not. For smaller fault currents, both the allowable time before the hermetic seal is damaged increases and the fault riearing time increases.
At all fault current levels, the primary breaker cleared, wh.'le the secon-dary breaker did not clear the fault within the allowable time.
As a result of this review, RGE has pr'oposed to install a 70 ampere backup circuit breaker in series with the primary circuit breaker.4 RGE l
has shown that the response of this new circuit breaker is properly coordinated to protect the AE-6 penetration under any postulated faillt condition.
l 3.1.2 Penetration Number AE-5.
This penetration has #8 AWG conducurs and is calculated by the manufacturer to ise able to withstand 1400 amperes for 0.54 second (including the Crouse-Hinds-supplied 10x 5
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safety factor). RGE does not expect mechanical damage at less than 4662 amperes (this is equal to 1400 x 3.33 or 1/3 of the original safety factor). The identified 480 VAC circuit is capable of supplying a maximum I
of 3500 amperes into the penetration. The primary breaker can clear tnis fault in 0.018 second, while the secondary fuse clears the fault in 0.002 second.
The backup device will clear the fault before~the primary l
l protective device at this level of fault current.
i It is calculated that the maximum I can be carried by this penetra-sc tion in a LOCA environment for 0.029 second before the penetration conductor temperature exceeds the meltin'g point of solder. Both protective devices I
will clear the fault within this time. At lower levels of fault current, both devices clear the fault in time to prevent solder melting.
3.1.3 Penetration Number CE-21.
Tnis penetration has 500 MCM 4
conductors and wa's type-tested oy the manufacturer and extrapolated by RGE to withstand 44,000 amperes for 10 cycles.
The 480 VAC circuit identified by RGE as typical can supply a maximum I f 20,000 amperes.
Both the sc I
primary and secondary breakers will clear the postulated fault within 0.45 and 0.50 second, respectively.
t It is calculated that the 20,000-ampere fault current can be carried by this penetration in a LOCA environment for 6.46 seconds before the pene-tration conductor temperature exceeds the melting point of the silver braze.
l doth the primary and the secondary circuit breaker will act in time to pre-vent damage to the hermetic seal of this penetration at this current level.
l Both circuit breakers respond faster than the penetration heat build-up limit for all current levels.
Since all in-containment components of this identified circuit are environmentally qualified for class lE service,5 NRC position 2 can be 3
applied.
This position requires only a single class lE circuit breaker for penetration protection where all components served by that penetration are qualified to class lE requirements.
i 3.1.4 Low-Voltage Penetration Evaluation. With-the initial temperature of the penetrations at 140*C (LOCA), penetrations AE-5 and i
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Tne protective devices for penetration AE-6, wnile not designed and utilized ivitnin the criteria described in Sec-tion 2.0 of tnis report., supply power for class lE components, and toerefore, are acceptable per NRC position 2.3 4
3.2 Typical Medium Voltage (21000 VAC) Penetration. Penetration I
numuers CE-25 and CE-27 nave been identified by RGE as typical of medium-voltage (4160 V) penetrations.
Tnese penetrations are used in parallel to supply power to one 6000 horsepower (HP) reactor coolant pump (RCP).
These pumps are the only medium-voltage load within containment.
Construction of these penetrations is of tne same materials and methods as discussed in Section 3.0.
The hermetic seal is silver brazed (T2 = 600 C).
Each penetration, containing three 750,000-MCM conductors, das type-tested by the manufacturer and found to have no damage at 80,000 amperes for 10 cycles (0.167 second).
The maximum I available (including that available from the source sc dnd from (ne suDtransient and transient response of the b000 HP motor fed cack through the single remaining penetration and caole) is 46,000 asym-metrical /36,800 symmetrical amperes.
The primary breaker overcurrent relay trips in 0.018 second, and the oackup breaker overcurrent relay trips in 0.17 second snould the primary creaker not clear the fault (Doth values based on 36,800 amperes).
It is calculated that the available 46,000-ampere asymmetrical fault current can ce carried by this penetration for 2.75 second before penetra-tion seal failure would occur.
Using the time-current characteristics, assuming 46,000 amperes is constant tnroughout the clearing time, the pri-mary breaker overcurrent will clear the fault in 0.018 second while tne secondary breaker overcurrent will clear the fault in 0.17 second.
3.2.1 Medium Voitage Penetration Evaluation. Penetrations CE-25 and CE-27 are designed cod utilized within the criteria described in Sec-tion 2.0 of this report.
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Additionally, RGE nas committed to improve the protection cnaracteris-tics for low magnitude fault currents.4 This will be accomplisned by installing a redundant set of overcurrent relays between the primary pro-tective relap and the penetration. This set of relays will actuate the backup breake/. RGE has shown that with this additional set of relays, the i
response of the circuit protective devices is properly coordinated to pro-tect the CE-25 and CE-27 penetrations under any postulated fault conditions.
3.3 Typical Direct Current Penetrations.
RGE has provided information of three typical direct-current power penetrations.I These penetrations are of the same construction as in Section 3.0, and the same metnods of determining the limiting heating factors were used.
3.3.1 Penetration Number CE-18. This penetration, constructed with number 2 conductors, provides 125 V DC power to the lift coil and was type-tested to De able to withstand a current in excess of 30,000 ampercs for 3 cycles with no mechanical damage. Tne maximum I available to sc this penetration is identified as 270 amperes. At this 270-ampere current, the two primary (both + and - leads) 50-ampere fuses will clear the line-to-line fault in 0.18 second or, should these fuses fail, the secondary 150-ampere fuse will clear the fault in 0.576 second.
L' It is calculated that the 270-ampere fault current can be carried by this penetration for 79.2 seconds Defore damage to the hermetic seal of the penetration occurs.
ihe primary and secondary fuses will clear this fault and all faults of less magnitude before the penetration temperature exceeds its qualification limit.
3.3.2 Penetration Number CE-17. This penetration, constructed with namoer 8 conductors, provides 125 V DC power for the rod drive circuit, and is calculated to be able to withstand 1400 amperes for 0.54 second.
The maximum I available to this penetration is 260 amperes. At this sc current,- the primary fuse will clear the line-to-line fault in,0.0004 second or, snould this fuse fail,.the secondary fuse will clear the fault in 0.0043 second.
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It is calculated tnat the 260-ampere fault current can ue carried by tnis penetration for S.28 seconds before damage to the hermetic seal of the penetration occurs.
Both the primary and the secondary fuses will clear this fault and all faults of less magnitude Defore tne penetration temper-ature exceeds its qualification limit.
3.3.3 Penetration Number CE-23.
Inis penetration, constructed with #10 conductors, provides 125 V DC control power and is calculated to be able to witnstand 1250 amperes for 0.27 second.
The maximum Isc availaole at tne penetration is 600 amperes. At this current,'tne primary fuse will clear the fault in 0.014 second. Tne secondary fuse will not nelt in time to prevent damage to the penetration ( 700 seconds operating time at 600 amperes).
It is calculated that the 600-ampere f ault current can be carried by this penetration for 0.39 second.
Tne primary fuse will, and the secondary fuse will not, clear this fault and all faults of less magnitude before the temperature of the penetration will exceed the melting point of solder.
As a result of this review, RGE nas proposed to install a new primary fuse (25A).4 The existing primary fuse (30A) will then De the secondary fuse. The two ruses will oe in series with penetration numoer CE-23.
RGE nas snown that the response times for these two fuses are properly cour-dinated to protect the CE-23 penetration under any postulated fault condi-tion.
3.3.4 Direct Current Penetration Evaluation. With the initial temperature of tne penetrations at 140*C as expected with a LOCA, penetra-tions CE-17, CE-18 and CE-23 are designed and utilized within the criteria described in Section 2.0 of this report.
3.4 Other Penetrations. RGE also provided information on penetration numbers AE-10, CE-1, and CE-8.I Penetration numbers AE-10 and CE-1 are part of instrumentation (10-50 mADC) current loops.
The transmitters of tnese are current-limited to 50 milliamperes while each penetration conduc-tor is rated at 12 ampe'res continuous.
Penetration number CE-19 is triaxial 9
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instrumentation signals, and tne circuit descrioed is equipment-limited to less than 200 watts (i.e., tne source of the signal would fail before 200 watts output is reached). A maximum I of ampere would be carried sc on a penetration conductor rated at 10 amperes continuous. No mechanical failures are postulated for these penetrations (construction and materials similar to the power penetrations previously described) even under accident conditions within containment.
A recent modification installed a low-voltage power, control, and instrumentation penetration tnat is IEEE-Standard-317-1972-qualified for an in-containment television monitor system.
Inis penetrdtion, for which appi1 cation data was not suomitted, is none the less qualified to IEEE Stan-dard 317-1972, assuming it is being used within specification limits.
4.0 SUMMY Inis evaluation looks at the capability of the protective devices to
- p. event exceeding tne design ratings of the selected penetrations in tne event of (a) a LOl'A event, (b) a f ault current tnrougn the penetration and, simultaneously, (c) a random failure of the circuit protective devices to clear the fault.
Tne environmental qualification tests of the penetrations is tne suoject of SEP Topic 111-12.
The penetrations identified witn power-limited instrumentation circuits are deemed suitaole under all postulated conditions.
After tne proposed modifications to the circuit protective devices are completed, witn a LOCA environment inside containment all penetrations are designed and utilized witnin the criteria described in Section 2.0 of tnis report wnicn assumes a soort circuit and random failure of circuit protec-tive devices.
RGE is investigating improvements for the protection of otiier penetra-tion circuits as a result of thit SEP topic.4 No completion date nas been established, aut any modifications are expected to De similar to those discussed in this report and in reference 4.
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r The review of Topic III-12, "Environmenti. Qua? ification" may result in enanges to the electrical penetration design and therefore, the resolu-tion af the subject SEP topic will De deferred to the integrated assessment, at which time, any requirements imposed as a result of this review will take into consideration design cnanges resulting from other topics.
5.0 REFERENCES
1.
RGE letter, Harry G. Saddock, Systematic Evaluation Program Topic Vill-4, " Electrical Penetrations of Reactor Containment",
R.E. Ginna Nuclear Power Plant, Unit No. 1, Dacnet No. 50-244, April 12, 1979.
2.
RGE letter, C. D. White, Jr., to Director of Nuclear Reactor Regula-tion, U.S. NRC, "SEP Topic VII-4--Electrical Penetration of Reactor Containment," July 21, 1980.
3.
NRC letter to RGE, "SEP Topic VIII-4," Marcn 30, 1981.
4.
RGE letter, J. E. Maier to 0: rector of Nuclear Reactor Regulation, NRC, "SEP Topic Vill-4, Electrical Penetrations," June 9, 1981.
5.
RGE letter, J. E. Maier to Director of Nuclear Reactor Regulation, NRC, "SEP Topic VIII-4, Electrical Penetrations," July 14, 1981.
6.
IPCEA Publication P-32-382, "Short Circuit Characteristics of Insulated Caule."
7.
General Design Criterion lo, " Containment Design" of Appendix A,
" General Design Criteria of Nuclear Power Plants," 10 CFR Part 50,
" Domestic Licensing of Production and Utilization Facilities."
Nuclear Regulatory Coanission Standard Review Plan, Section 8.3.1, "AC Power Systems (Onsite)."
9.
Regulatory Guide 1.63, Revision 2, " Electrical Penetration Assemolies in Containment Structures for Light-Water-Cooled Nuclear Power Plants."
10.
IEEE Standard 317-1976, "IEEE Standard for Electric Penetration Assem-blies in Containment Structures for Nuclear Power Generating Stations."
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