ML17261A181

Forwards Evaluation of SEP Topic VIII-4, Electrical Penetrations of Reactor Containment

ML17261A181
Person / Time
Site:	Ginna
Issue date:	03/24/1980
From:	Ziemann D Office of Nuclear Reactor Regulation
To:	White L ROCHESTER GAS & ELECTRIC CORP.
References
TASK-08-04, TASK-8-4, TASK-RR NUDOCS 8004180094
Download: ML17261A181 (26)

Text

4

~y,Q RE00 P0 Cy

+a*++

Docket No. 50-244.

UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON,D. C. 20555 March 24, 1980

,'ji', MAR 28 1980 I",

i;I'~< -=~4 Mr. Leon D. White, Jr.

Vice President Electric and Steam Production Rochester Gas 8 Electric Corporation 89 East Avenue Rochester, New York 14649 Distr. to Ginna J'~ GARB

Dear Hr. White:

RE:

SEP TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAINMENT Enclosed is a copy of our evaluation of Systematic Evaluation Program Topic VIII-4 Electrical Penetrations of Reactor Containment.

This assessment compares your facility, as described in Docket No. 50-244 with the criteria currently used by the regulatory staff for licensing new facilities.

Please inform us if your as-built facility differs fr om the 1 icensing bas is assumed i n ou r assessment.

We have discussed this assessment with your staff and believe the facts concerning your plant are correct.

Therefore, our review of this topic is complete and this evaluation will be a basic input to the integrated safety assessment for your facility unless you identify changes needed to reflect the as-built conditions at your facility.

This. topic assess-ment may be revised in the future if your facility design is changed or if HRC criteria relating to this topic are modified before the integrated assessment is completed.

S incerely,

Enclosure:

Completed SEP Topic VIII-4 cc w/enclosure:

See next page Dennis L. Zieman, Chief Operating Reactors Branch ¹2 Division of Operating Reactors

~ I

Mr. Leon D. White, Jr. March 24, 1980 CC Harry H. Voigt, Esquire

LeBoeuf, Lamb, Leiby 5 MacRae 1757 N Street; N.

W.

Washington, D. C.

20036 Mr. Michael Slade 12 Trailwood Circle Rochester, New York 14618 Rochester Coranittee for Scientific -Information Robert E. Lee, Ph.D.

P. 0.

Box 5236 River Campus Station Rochester, New York 14627 Jeffrey Cohen New York State Energy Office Swan Street Building Core 1, Second Floor Empire State Plaza

Albany, New York 12223 Director, Technical Development Programs State of New York Energy Office Agency Building 2 Empire State Plaza

Albany, New York 12223 Rochester Public Library 115 South Avenue Rochester, New York 14604 Supervisor of the Town of Ontario 107 Ridge Road West

Ontario, New York 14519 Director, Technical Assessment Division Office of Radiation Programs (AW-45g)

U. S. Environmental Protection Agency Crystal Mall 82 Arlington, Virginia 20460 U. S. Environmental Protection Agency Region II Office'TTN:

E IS COORDINATOR 26 Federal Plaza New York, New York 10007 Herbert Grossman, Esq.,

Chairman Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comnission Washington, D. C.

20555 Dr. Richard F. Cole Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comnission Washington, D. C.

20555 Dr.

Emmeth A. Luebke Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comnission Washington, D.

C.

20555 Mr. Thomas B. Cochran Natural Resources Defense Council, Inc.

1725 I Street, N.

W.

Suite 600 Washington, D. C.

20006

~

~

SEP TECHNICAL EVALUATION TOPIC VIII-4 r

ELECTRICAL PENETRATIONS OF REACTOR CONTAIVaAENT R.E.

GINNA NUCLEAR STATION, UNIT NO.

1 Rochester Gas and Electric Corporation Docket No. 50-244 1-15-80

~

i

CONTENTS

1.0 INTRODUCTION

~

~

~

~

~

~

1 io0 CRIT R~%

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

0 2

3.0 DISCUSSION AND EVALUATION o

3 3.1 Typical Low Voltage (0-1000 VAC) Penetrations

~

~

~

~

~

~

5 3.1

~ 1 Penetration Number AE-6 3.1.2 Penetration Number AE"5 3.1.3 Penetration Number CE"21 3.1.4 Low Voltage Penetration Evaluation

~

~

~

~

~

1

~

~

~

~

l

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

5 5

6

~

~

7 3.2 Typical Medium Voltage

(>1000 VAC) Penetrations 3.2.1 Medium Voltage Penetration Evaluation 3.3 Typical Direct Current Penetrations 7

8 8

3.3.1 3.3.2 3.3.3 3.3.4 Penetration Number CE-18 Penetration Number CE-17 Penetration Number CE-23 Direct Current Penetration

~

~

~

Evalu

~

~

~

~

~

~

~

~

tat1on

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

8 9

9 10 3.4 Other Penetrations

~

~

~

~

\\

~

~

~

~

~

~

10 4 ~

SUii8Y

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

t

~

~

0

~

i 11 5 ~

REPERENCES

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

12 11

SEP TECHNICAL EVALUATION TOPIC VIII-4 ELECTRICAL PENETRATIONS OF REACTOR CONTAIiiEiVT R.E.

GINNA NUCL-"-AR STATION, VHI NO.

1.0 INTRODUCTION

This review is part of the Systematic Evaluation Program (SEP),

Topic VIII-4.

The evaluation provided by Rochester Gas and Electric C

(RGE) has demonstrated the adequacy of the penetzations and the circuit protective devices during normal operation, except as shown an Section 3.3.3.

The objective of this review is to determine the capa-bility of the overcurzent protective devices to prevent exceeding the design rating of the electrical penetrations through the reactor con-tainment during short circuit conditions at LOCA temperatures.

General Design Cziterion 50, "Containment Design Basis" or Appen-dix A, "General Design Criteria for Nuclear Power Plants" to 10 CFR Part 50 requizes that penetzations be designed so that the containment structure can, without exceeding the design leakage rate, accommodate the calculated

pressure, temperature, and other environmental condi-tions resulting from any loss-of-coolant accident (LOCA).

IEEE Standard 317, "Electric Penetration Assemolies in Containment Structures for Nuclear Power Generating Stations",

as augmented by Regulatory Guide 1.63, provides a basis of electrical penerrations acceptable to the staff.

Specifically, this review will examine the protection of typical electrical penetrations in the containment stzucture to determine the ability of the protective devices to cleaz the circuit during a short circuit condition prior to exceeding the containment electrical pene-tration test or 'design ratings with initial assumed LOCA temperatures.

2.0 CRITERIA IEEE Standard 317, "Electric Penetrat'on Asse bes in Conta'r-ent Structures zor Nuclea Powe" Generating Stations" as supplemented by Nuclear Regulatory Commission Regulatory Guide 1.63, "Electric Penetra-tion Assemblies in Containment Structures for Light-WaterWooled Nuc-lear Power Plants" provides the oasis 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 cir-cuit current and duration shall be the maximum short circuit current in amperes that the conductors of a circuit can carry for a specizied duration (based on the operating time of the primary overcurrent protective device or apparatus of the circuit) following cont:nuous operation at rated continuous current without the temperature oz the conductors exceeding their short ci.rcuit design limit with all other conductors in the assembly carrying their rated continuous current under the specified normal environmental conditions."

This paragraph is augmented by Regulatory Guide 1.63, Para-graph C-1 "The electric penetration assembly should be designed to withstand, without loss of mechanical integrity, the maximum possible fault current versus time conditions that could occur given single random failures 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 snort 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 typ:cal containment penetra-tions being a

LOCA temperatures concurrent w'th a random =alure of the circuit protective devices will be analyzed.

RGE has provided information (Reference

1) on typical penetra-tions.

All but one were manufactured by Grouse-Hinds, who no longer makes these penetrations.

Grouse 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 the hermetic seal of the penetration occurs, melting of the solder in the nermetic seal of the penetrations (though some use a silver braze instead) must occur (361 F, 180 C).

Thi.s temperature is used because it is the lowest temperature 0

that affects the penetration seal.

Other mate ials, while affecting the strain relief of the penetration at lower temperatures, do not affect the hermetic seal.

This limiting temperature is determined by the analysis of the construction of the penetrations rather than testing.

The Ginna 1 Technical Specification allows for initial steady 0

state temperatures of the penetration environment up to 120 F

(49 C).

Under accident conditions, a peak temperature of 285 F

0

~

0 (140 C) is expected.

In those penetrations with conductors larger than 02 copper, the limit was not heat input but mechanical forces generated by electro" magnetic coupling, and the limits put on these,was determined

'oy tests, with no mechanical failure of the penetration.

Smaller penetration conductors are not subject to failure by mechanical forces when used within their maximum current rating.

RGE also used the Insulated Power Cable Engineers Association publication, P-32-382, entitled "Short Circuit Characteristics of

Insulated Cable" to determine separate limiting factors on the conduc-tors of the penetration.

Where these figures were more conservative than the Grouse-Hind f gures, they were used instead.

In supplying the value of the maximum short circuit current avail-able (I

),

RGE supplied values for a three"phase (on a three-phase sc system) bolted fault; this type being able to supply the most heat into the penetration.

The I value supplied by RGE takes both the sym-sc metrical AC component and the peak DC offset component.

In the RGE

analysis, the I was held to the maximum value for all phases when sc only one phase can have the full initial offset, and despite the fact that the DC component decays.

This provides an additional safety fac-tor in their calculations.

RGE did not assume that all other penetra-tion conductors were carrying their maximum rated current, but applied the normal operating current.

The following formula (Reference

6) was used to determine the time allowed for a short"circuit before the penetration conductor temperature would exceed the melting point of s'older.

c 2

T2 + 234 A

t 0,0297 log T

34 1

0.0297 A

1 2

I 1

sc (Formula 1) where t

~

Time allowed for the snort circuit seconds I

Short circuit current amperes sc A

Conductor area circular mils Tl Maximum operating temperature (140 C, LOCA condition)

T2

~

Maximum short circuit temperature (180 C, tem-perature for melting solder).

Th'is is based upon the heating effect of the short circuit current on the conductors.

it shou d be not d tha" the short c'rcuit temperature-time limits of the conductors in this report vary from the values calculated by RGE (Reference

1) even though the same methods are used.

RGE has utilized an initial temperature of 40 C while this review uses an initial temperature of 140 C

(LOCA condition) for the penetration.

A 0

pre-fault penetration conductor temperature equal to the peak LOCA I

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 T

ical Low Voltage (0-1000 VAC) Penetrations.

RGE has provided information on three typical low-voltage AC penetrations (Reference 1).

3.1.1 Penetration Number AE-6.

This penetration has 82 AWG conductors and was type-tested to 37,400 amperes for 3 cycles by the manufacturer, Crouse-Hinds.

The I available on sc the identified 480-V circuit is 9600 amperes.

Using Formu-la 1, this current can be carried for 0.06 second before the penetration conductor temperature exceeds the melting point of solder while under a LOCA environment.

The primary cir-cuit breaker responds within this 'time (.018 second).

The secondary circuit breaker does not.

For smaller fault cur-

rents, both the allowable time before the hermetic seal is damaged increases and the fault clearing time increases.

At all fault current levels, the secondary breaker did allowable time.

the primary breaker

cleared, while not clear the fault within the 3.1.2 Penetration Number AE-5.

This penetration has 88 AWG conductors and is calculated by the manufacturer to be able to withstand 1400 amperes for 0.54 second (including the Crouse-Hinds-supplied 10 safety factor).

RGE does not x

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

'nto the penetraz.'on.

The sc primary breaker can clear this fault in.018 second, while the secondary fuse clears the fault in.002 second.

The backup device will clear the fault before the primary pro-tective device at this level of fault current.

It is calculated that the maximum I can be carried by sc this penetration in a LOCA environment for.029 second before the penetration conductor temperature exceeds the melting point of solder.

Both protective devices will clear the fault within this time.

At lo~er levels of fault current, both devices clear the fault in time to prevent solder melting.

3.1.3 penetration Number CE-21.

This penetration has 500 NCH conductors and was type"tested by the manufacturer and extra-polated by RGE to withstand 44,000 amperes for 10 cycles.

The 480 VAC circuit identified by RGE as typical can supply a

maximum I of 20,000 amperes.

No data was submitted on sc mechanical stress at this current level.

Both the primary and secondary breakers will clear the postulated fault within 0.45 and 0.50 second, respectively.

It is calculated that the 20,000-ampere zault current can be carried by this penetration in a LOCA environment for 0.82 second before the penetration conductor temperature exceeds the melting point of solder.

Both the pzimary and the secondary circuit breaker will act in time to prevent damage to the hermetic seal of this penetration at this cur-rent level.

The primary circuit breaker responds faster than the penetration heat build-up limit for all current levels.

The secondary circuit breaker will clear higher magnitude faults with sufficient speed to prevent

damage, but at some

lower magnitude faults, the fault cleari.ng time is long enough for the penetration to exceed the melting point of solde 3.1.4 Low-Voltage Penetration Evaluation.

With the initial temperature of the penetrations at 140 C (LOCA),

pene-0 tration AE-5 is designed and utilized within the criteria described in Section 2.0 of this report.

Penetrations AE-6 and CE-21 are not designed and utilized within the criteria described in Section 2.0 of this report.

In all cases looked at, the secondary clearing device rating or nominal value exceeded the penetration continuous current rating supplied, thus relying on motor overload relays, for which no information was supplied, as secondary protective devices for the penetration.

3.2 Typical Medium Voltage

()1000 VAC) Penetration.

Penetration numbers CE-25 and CE-27 have been identified by RGE (Reference

1) as typical of medium-voltage (4160 V) penetrations.

These penetrati.ons are used in parallel to supply power to one 6000 horsepower (HP) reac-tor coolant pump (RCP).

These pumps are the only medi.um-voltage load within containment.

Construction of these penetrations is of the same materials and methods as discussed in Section 3.0.

The nermetic seal is silver brazed.

Each penetration, containing three 750,000-MCM conductors, was type-tested by the manufacturer and found to have no damage at 80,000 amperes for 10 cycles

(.167 second).

The maximum I available included that available from the sc source and the subtransient and transient response of the 6000 HP motor fed back through the single remaining penetration and cable.

46,000 asymetrical/36,800 symetrical amperes I are available.

No sc data was submitted by RGE on mechanical stress 'at this current level.

The primary breaker overcurrent relay trips in.018 second, and the

~

~

backup breaker overcurrent relay trips in.17 secopd should the primary breaker not clear the fault (both values based on 36,800 amperes).

It is calculated that the available 46,000-ampere asvmetrical fault. current can be carried by this penetrati.on for 0.35 second before penetration seal failure would occur.

Using the time-current charac-teristics, assuming 46,000 amperes is constant throughout the clearing time, the primary breaker overcurrent will clear the fault in.018 sec-ond while the secondary breaker overcurrent will clear the fault in 0.17 second.

3.2.1 Medium Voltage ?enetration Evaluation.

Penetrations CE-25 and CE-27 are designed and utilized within the criteria described in Section 2.0 of this report.

From the curves supplied, it could not be determined what effect motor overloads would have, as both the primary and secondary switchgear do not protect at the penetration con-tinuous rated current.

Moreover, should one of the two feeders fail without a s'nort circuit, the remaining penetra-tion does not have the capability to carry the RCP normal-running current by itself.

The continuous current rating of each penetration is 450 amperes, while full-load current of a 6000 HP, 4160 V motor is approximately 700 amperes.

Conceiv-ably, the remaining penetration would exceed its qualifica-tion temperature limit under this condition within 6.5 min-utes as there is no inherent protection in the circuit for a single-cable break without a short circuit condition.

3.3 Typical Direct Current Penetrations.

RGE has provided infor-mation of three typical direct-current power penetrations (Reference 1).

These penetrations are of the same construction as in Section 3.0, and the same methods of determining the limiting heating factors were used.

3.3.1 Penetration Number CE-18.

This penetration, construc-ted with number 2 conductors, provides 125 V DC power to the

lift coil and was type-tested to be able to withstand a cur-rent in excess of 30,000 amperes for 3 cycles with no mechan-ica'amage.

he maximum I ava 'ab1e to this penetrarion sc is identif'd 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.18 second or, should these fuses fail, the secondary 150-ampere fuse will clear the fault in.576 second.

It is calculated that the 270-ampere fault current can be carried by this penetration for 79.2 seconds before damage to the hermetic seal of the penetration occurs.

The 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, construc-ted with number 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 sc this penetration is 260 amperes.

At this current, the pri-mary fuse will clear the line-to-line fault in.0004 second or, should this fuse fail, the secondary fuse will clear the fault in.0043 second.

It is calculated that the 260-ampere fault current can be carried by this penetration for 5.28 seconds before damage to the hermetic seal of the penetration occurs.

Both the pri-mary and the secondary fuses will clear this fault and all faults of less magnitude before the penetration temperature exceeds its qualification limit.

3.3.3 Penetration Number CE-23.

This penetration, construc-ted with 810 conductors, provides 125 V

DC control power and is calculated to be able to withstand 1250 amperes for 0.27 second.

The maximum I available at the penetration sc

t

~

is 600 amperes.

At this current, the primary fuse will clear the fault in.014 second.

The secondary fuse will not melt in time to prevent damage to the penetration

(>700 seconds operating time at 600 amperes).

It is calculated that the 600-ampere fault current can be carried by this penetration for 0.39 second.

The 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.

3.3.4 Direct Current Penetration Evaluation.

With the ini-tial temperature of the penetrations at 140 C as expected 0

with a LOCA, penetrations CE-18 and CE-17 are designed and utilized within the criteria described in Section 2.0 of this report.

However, penetration CE-23 is not utilized within the criteria descri.bed ip Section 2.0 of this report, regard-less of the initial penetration temperature.

3.4 Other Penetrations.

RGE also provided information on pene-tration numbers AE-10, CE-1, and CE-8 (Reference 1).

Penetration num-bers AE-10 and CE-1 are part of instrumentation (10-50 mADC) current loops.

The transmitters of these are current-limited to 50 milli" amperes while each penetration conductor i.s rated at 12 amperes contin-uous.

Penetration number CE-19 is triaxial instrumentation signals, and the circuit described is equipment"limited to less than 200 watts (i.e

, the source of the signal would fail before 200 watts output is reached).

A maximum I of 1 ampere would be carried on a penetra-sc tion conductor rated at 10 amperes continuous.

No mecnanical failures are postulated for these penetrations (construction and materials simi-lar to the powe" penetrations previously described) even under accident conditions within containment.

A recent modification installed a low-voltage power, control, and instrumentation penetration that is IEEE-Standard-317-1972-qualified 10

for an in-containment television monitor system.

This penetration, for which application data was not submitted, is none the less qualified to IEEE Standard 317-1972, assuming it is being used w thin specification limits.

4. 0 SENARY This evaluation looks at the capability of the protective devices to prevent exceeding the design ratings of the selected penetrations in the event of (a) a LOCA event,

('o) a fault current through the penetra-tion and, simultaneously, (c) a random failure of the circuit protec-tive devices to clear the fault.

The environmental qualification tests of the penetrations is the subject of SEP Topic III-12.

The penetrations identified with power-limited instrumentation circuits are deemed suitable under all postulated conditions.

With a LOCA environment inside containment, penetrations AE-5, CE-25 and -27, CE-17, and CE-18 are designed and utilized within the criteria described in Section 2.0 of this report which assumes a short circuit and random failure of circuit protective devices.

Penetration CE-21 is utilized within the criteria described in Section 2.0 of this report.

However, the secondary breaker does not adequately protect the penetration for faults of less than bolted fault magnitudes.

The secondary breaker for penetration AE-6 is not utilized within the criteria of Section 2.0 of this report.

At an initial temperature of normal environment, this penetration is properly utilized.

The seal of penetration CE-23 could be voided with the failure of the primary fuse to clear the fault, as the operating time of the bac-kup fus'e will not protect it from short circuits up to the maximum.,

I supplied by RGE.

sc 11

Should one penetration of the penetration pair, CE-25 and CE-27, have an open circuit in one of its three conductors, the normal opera-ting current for the RCP would cause the remain'ng penetrat'on conduc-tor to exceed the melting point o= solder within 6.5 minutes.

.nis condition occurs because the RCP breaker protective setpoints disregard the fact that the use of one feeder to supply the RCP will cause con-ductor and penetration overheating and there is no provision to monitor the integrity of the parallel conductors.

The review of Topic III-12, "Environmental Qualification" may result in changes to the electrical penetration design and therefore, the resolution of the subject SEP topic will be deferred to the integrated assessment, at which time, any requirements imposed as a

result of this review will take into consideration design changes resulting from other topics.

5.0 REPERENCES 1.

Harry G. Saddock, Systematic Evaluation Program Topic VIII"4, "Electrical Penetrations of Reactor Containment",

R.E. Ginna Nuc" lear Power Plant, Unit No.

1, Docket No. 50-244, April 12,

1979, RGE letter.

2.

General Design Criter'on 16, "Containment Design" of Appendix A, "General Design Criteria of Nuclear Power Plants,"

10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities."

3.

Nuclear Regulatory Commission Standard Review Plan, Section 8.3.1, "AC Power Systems (Onsite)."

4.

Regulatory Guide 1.63, Revision 2, "Electrical Penetration Assem<<

blies in Containment Structures for Light-Mate"-Cooled Nuclear Power Plants."

12

5.

IEEE Standard 317-1976, "IEEE Standard for Electric Penetration Assemblies in Containment Structures for Nuclear Power Generating Stations."

6 ~

'XPCEA Publication P-32-382, "Short Circuit Characteristics of Insulated Cable."

13

~) i