ML20207U112

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Forwards Response to NRC 870206 Questions Re High Impedence Faults Elimination of Electric Isolation Deficiencies & Status of Interim Compensatory Measures & IE Info Notice 85-009.Fire Watches Still Maintained
ML20207U112
Person / Time
Site: Quad Cities  Constellation icon.png
Issue date: 03/13/1987
From: Johnson I
COMMONWEALTH EDISON CO.
To: Harold Denton
Office of Nuclear Reactor Regulation
References
2863K, IEIN-85-009, IEIN-85-9, NUDOCS 8703240627
Download: ML20207U112 (19)
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/ One First Nstional Plaza, Chica00, INinois

"~ . [\ " J Address Reply to: Post Omco Box 767.

N/ Chicago, lHinois 60690 0767 March 13, 1987 l

l Mr. Harold R. Denton U.S. Nuclear. Regulatory Commission Office of Nuclear Reactor Regulation Washington, DC. 20555

Subject:

Quad Cities Station Units 1 and 2 Response to NRC Staff Questions on High Impedence Faults and NRC IE Notice 85-09 NRC Docket Nos. 50-254 and 50-265

Dear Mr. Denton:

On February 6, 1987, we received questions from Dr. T.

Chandrasekaran of your staff concerning high impedence faults elimination of electric isolation deficiencies and the status of interim compensatory measures. Attached, please find our response to the questions pertaining to these subjects.

A request was also made as to whether interim compensatory Eeasures were still required for Quad Cities Station Units 1 and 2.

All of the safe shutdown hardware modifications have been completed and their corresponding interim measures are no longer required. At this time fire watches are still maintained until work on fire detection and suppression systems are completed.

Please direct any questions you may have regarding this Eatter to this office.

Yours very truly, I. M. J hn on Nuclear Licensing Administrator

/klj att. I cc: A.B. Davis T. Rotella NRC Resident Inspector-Quad Cities 2863K B703240627 DR 870313 $

ADOCK 05000254 1 PDR ' I g

ATTACHMENT A Response to NRC Staff Questions Pertainino to Quad Cities Station Appendix R Alternate Shutdown Methods I

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1. High Impedance Faults Elimination
a. How many control power fuses are involved for the electrically-operated breakers at the 4-kV and 480-V switchgear?

Response

The following breakers supply power to nonsafe shutdown loads:

_-kV 4 Switchgear 13 Breakers 1301, 1302, 1303, 1304, 1305, 1306, 1307, 1309, 1310, 1313 4-kV Switchgear 14 Breakers 1401, 1402, 1403, 1404, 1405, 1406, 1407, 1408, 1411, 1412, 1414 4-kV Switchgear 23 Breakers 2302, 2303, 2304, 2306, 2307, 2308, 2310, 2311, 2312, 2313, 2314 4-kV Switchgear 24 Breakers 2401, 2403, 2404, 2405, 2407, 2408, 2409, 2410, 2411, 2412, 2414 4-kV Switchgear 13-1 Breakers 1322, 1323, 1326 4-kV Switchgear 14-1 Breaker 1422

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4-kV Switchgear 23-1 Breakers 2322, 2325 4-kV Switchgear 24-1 Breaker 2428 480-V Switchgear 18 Breakers 183B, 183C, 183D, 1848, 1858, 185C, 1868, 1860 480-V Switchgear 19 Breakers 193B,193C, .193D,194B,194C,195B,195C,1950 480-V Switchgear 28 Breakers 2838, 283C, 2830, 2848, 285A, 2858, 285C, 286C 480-V Switchgear 29 Breakers 2938, 293C, 293D, 294B, 294C, 2958, 295C, 2950 The control power fuses-for these breakers would have'to be pulled.

The fuses would only be pulled on the switchgear that is being used.

to power equpment for safe shutdown in the area of the fire. The exact number of fuses pulled for each shutdown path is given in the response to Question 1.b.

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1.b. What is the maximum number of fuses that may have to be pulled out at any one time following a fire event?

Response

Tabulated below are the number of breakers that would have to have their control power fuses pulled for each safe shutdown path and the time frame in which the fuses would have to be pulled.

Safe Shutdown Path Number of Breakers Time Frame A 9 14 minutes after scram.

13 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

B 10 14 minutes after scram.

12 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

C 10 14 minutes (for a fire in after scram.

Fire Area TB-I) 31 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

C 10 14 minutes (for a fire in after scram.

Fire Zone 8.2.8.C) 23 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

D 9 14 minutes (for a fire in after scram.

Fire Zone 1.1.1.1.S, 11.2.1 and 11.2.2) 21 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

Safe Shutdown Path Number of Breakers Time Frame D 9 14 minutes (for a fire in after scram.

Fire Zone 8.2.8.A) 21 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

D 9 14 minutes j (for a fire in after scram.

Fire Area TB-III) 30 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

D 9 14 minutes (for a fire in after scram.

Fire Zone 11.1.1.B) 30 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

El 18 14 minutes after scram.

11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

E2 18 14 minutes (for a fire in after scram.

Fire Area TB-II) 11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

F 15 14 minutes after scram.

11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> l after scram.

H 8 14 minutes after scram.

i 11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

K 9 14 minutes (for a fire in after scram.

Fire Zone 8.2.8.D) 11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

K 9 14 minutes (for a fire in after scram.

Fire Area SB-I) 11 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram.

As can-be seen from thestable, the largest number of breakers that have. to have their fuses pulled in the first 14 minutes after scram (time required to initiate reactor water makeup) is-18 for shutdown.

paths El and E2. It'only takes a few seconds to i ' a fuse. This amount of fuse pulling would not be a problem for the operators.

The largest number of breakers requiring fuse pulling during the first three hours after scram (the time allowed.before suppression pool cooling must be initiated) is:31 for shutdown path D.

Fuse pulling is part of the operating training course and must be successfully demonstrated in order to pass the course. Pulling fuses is part of the routine work that an operator must perform before maintenance can be performed on equipment.

1.c. In view of your statement, " Removal of the fuses precludes spurious closure and makes it unnecessary to rack out the breakers" (Ref. 4, page 9.1-2, top paragraph), state clearly, whether for'the electrically-operated breakers at the 4-kV or 480-V switchgear, you will have to trip them first and subsequently remove their control power fuse.

Response

The fuses can be removed before the breakers are tripped on 4-kV Switchgears 13-1, 14-1, 23-1, and 24-1 and 480-V Switchgears 18, 19, 28, and 29. After fuse removal, the breakers are then mechanically tripped by pressing a button on the breaker.

This routine of removing the control power fuse before tripping the breaker is the method for which all operators are trained. This routine prevents the accidental opening or closing of the breaker from a remote control station (e.q. control room) and thus, is for the operators own safety.

This routine must be successfully demonstrated for the operator to pass the training course.

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l.d. Are the fuses readily accessible?

Response

The fuses are located at the top of the breaker compartment panel, on the face of the switchgear, for the 4-kV switchgear and are easy to locate, identify, and remove. The fuses for the .480-V switchgear are located at one end of the bus and these fuses are also easy to locate, identify, and remove.

Fulling fuses is part of the operator training course and must be demonstrated to pass the course. Prior to performing maintenance on equipment, the operator must remove the control power fuse and trip the breaker. Therefore, this is a routine that is performed on a regular basis by the operators.

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1.e. Do your procedures include explicit instructions to operators for pulling out fuses when needed?

Responses The procedures include specific instructions about which breakers should have their control power fuses pulled. The exact fuses to be pulled are identified in the procedure by bus number, compartment number, and fuse number.

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Fuse pulling is part of the operator training course and must be demonstrated to pass the course. Pulling fuses is part of the routine work that an operator performs prior to maintenance being performed on equipment.

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How soon in the fire scenario will the fuses have to be pulled out so that the time supply of power to the safe shutdown loads is not compromised?

Respong The time frame for fusa pulling is provided in the response to Question 1.b.

2.a What does "preconfiguration of the bus prior to energization" mean?

Response

The statement means that the breakers will be manually closed before the bus is energized. As stated in the response to Question 2.d, a maximum of three breakers would have to be closed to eliminate l

IN 85-09 concerns.

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I 2.5 With regard.to you'r statement, "these breakers are normally in the- ,

desired positionslat all times and are unlikely to! require attention

even if their fuses are damaged," explain why damage to a cc:. von fuse need not be a concern.

Response

The most typical damage that the con ~ trol power fuses can sustain will teruit in an open fuse. If the contro1' power fuses are open, the b'reakers will not spariousif change their position. With open control power fuses, breakers can only charge their positions by' man'tal action or overload trip. Since Breakers MF 28 and MF 29.are normally closed, they would probably not have to be manually closed during shutdown. Breakers 1819 and 1918 are normally opens so for a fire in Fire Zones 8.2.7.C, 2.0, 3.0, and 6.3, these breakers would be manually closed, t

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2.c Will the jacking handle be handy for manual closing of the applicable breakers?

Response

The jacking handles are located in a cabinet in the vicinity of the 4-kV and 480-V switchgear. As stated in the response to Question 2.d, the maximum number of breakers that would have to be manually closed is three.

2.d What are the maximum number of breakers that may require closing at one time?

Response

Listed below are the fire areas, the shutdown path for each fire area, and the number of breakers that may have to be manually closed if the fuses common to both the local and remote control circuits are damaged (Informa-tion Notice No. 85-09 concern).

Breakers to be Fire Area Safe Shutdown Path Manually Closed RB-1 A, D 0 RB-2 B, L 0 RB-1/2 El, F 0 TB-I C 0 TB-II E2, H 2(Breakers 1819, and 1918 )

TB-III D 0 TB-IV A,C,D,K 0 Crib House El, E2, F, H 0 Radwaste All are available O SB-I E2, K 3(Breakers 1819, 1918 and MF 29 )

SB-II All are available 0 Off-Gas Filter All are available 0 Building Outside All are available 0

-Response to 2.d (Cont'd) Page 2 Breakers to be Fire Area Safe Shutdown Path Manually Closed Unit 1 Primary All are available O Containment Unit 2 Primary All are available O Containment As can be seen from the above list, the lat gest number of breakers that would have to be manually closed is 3 for a fire in Fire Area TB-I (Control Room, Cable Spread Room, Auxiliary Electric Equipment Room).

2e. How soon in the fire scenario will the breakers have to be manually closed so that local control circuits will be available when they ara needed?

Response

Breakers 1819 and 1918 may have to be manually closed if a fire occurs in Fire Areas TB-II (Fire Zone 8.2.7.C) or SB-I (Fire Zones 2.0,3.0,6.3).

This would need to be done within 14 minutes of reactor scram to ensure that the RCIC inboard steam supply valve (M01-1301-16) is open.

As a correction to our previous information sent to you in submittal dated December 30, 1986 on " Quad Cities Units 1 and 2 Responses to NRC Concerns on High Impedance Faults and NRC Information Notice 85-09,"

Breaker MF-28 does not need to be operated for a fire in Fire Zones 8.2.5, 8.2.6.E and 8.2.7.D.

Breaker MF-29 may have to be manually closed if a fire occurs in Fire Area SB-I. This would need to be done within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of reactor scram to ensure power to the RHR SW pump cubicle fans. As a correction to our previous information sent to you in submittal dated December 30, 1986, Breaker MF-29 does not need to operate for a fire in Fire Zone 1.1.2.3.

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s 2.f Do your. procedures include explicit instructions ' to the operators

-for performing the above tasks.when they are needed?-

Response

The procedures iaentify the. bus number, compartment number, and -

fuse number for the_ breakers that ' require control- fuse pulling.

Opening and closing breakers is part of-the operator training course and must be successfully demonstrated to' pass the course. Opening and closing breakers,is routinely performed by the operators to remove equipment from service for maintenance and putting equipment back into service af ter maintenance.

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- 2.g Is.it possible that during-the time interval between tripping the

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applicable-breakers at the switchgears.and pulling out their control

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power fuses, spurious closures of the breakers can occur resulting-l in an unrecoverable situation?-

Response

It is not possible to have an unrecoverable situation.' The control power fuses will be pulled before the breaker is tripped. Once the

breaker -is tripped, it cannot spuriously close because the control

. power fuse has been removed. Removing the control power fuse before tripping tiie breaker is the routine method of operation when opening breakers.

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