ML20085K180

Responds to Generic Ltr 91-06, Resolution of Generic Issue A-30, 'Adequacy of Safety-Related DC Power Supplies.' Each Div of Dc Power Distribution Sys Has Common Alarm Window on Control Room Panel CP-35

ML20085K180
Person / Time
Site:	Waterford
Issue date:	10/24/1991
From:	Burski R ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR GL-91-06, GL-91-6, W3F1-91-0601, W3F1-91-601, NUDOCS 9110300189
Download: ML20085K180 (10)

Text

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.O YB ENTERGY '"I'"*""*""""'

i it.F,Dueski W3rl-91-0601 A4.05 .

QA October 24 1991 U.S. Nuclear Regulatory Commission -

ATTH: Document Control Dock Washington, D.C. 20555 Subjects Watorford 3 SES Docket No. 50-382 Licenro No. NPP-38 Genoric letter 91-06/ Resolution of Generic Issuo A-30 "Adoquacy of Safoty-Rolated DC Pwr Supplies," pursuant To 10 CFR 50.54 (f)

Gentiomont This letter is submitted in responso to Generic Lottor 91-06 1 issued April 29, 1991. The Generic Lotter f *L) requested responses to questions that would provido the staff with information to dotormine if any further action is required by Waterford 3_in resolution of Genoric Issuo (GI) A-30. The GI is concerned with adequacy of-safety-related de power in operating nuclear power plants, especially in the area of multiple and common causo failuros.

Attached you will find the completed onclosure from GL 91-06 (Attachment 1). The attachment contains supporting discussion where applicable for answers to questions that requiro como clarification.

Should you havo-any additional questions pleano fool froo to '

contact me or Oscar pipkins at (504)739-6707.

Very truly yours, A Sp

. RFU)QPPfdc 4 Attachment

//cof # R.D. Martin, NRC Region IV

1. 7 D.L. Wigginton, NRC-NRR R.D. McGohoo N.S. Reynolds j NRC Resident Inspectors Offico

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-UNITED STATES OF AMERICA ,

NUCLEAR lil:GULA'IORY COMMISSION In tho matter of- )

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Entergy Operations, lucorporated ) Docket No. 50-382 3 Waterford 3 Steam Elect:4c Station )

i AFFil)AVIT l L.W. laughlin, being duly Aworn, hereby deposes and says that he is Manager, i Lleensing - Waterford 3 of Entergy Operations, Incorporated; that he is duly authorized to sign alul file with the Nuclear Regulatory Commission the attached Hesponno to NitC Genoric Letter 91-0Gt that he is famillar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief. ,

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LW%Ihughlin' /

-Majin'geti ,4}censlag - Waterfard 3

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STATE OF LOUlslANA )

) ss PAHISil OF ST. CilARLES

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Subscribed and sworn to before me, a Notarytubtip in and for the Parish und Stato above ucmod this 2 ye! day of O..#~/- , 1991. '

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ATTACIIMENT 1 10 CFR 50. 5 4 (f) Request - Generic Issue (GI).A-30 " Adequacy of Safety-Related DC Power Supplies" QuqEtions The following information is to be provided for each unit at each sito:

1. Unit Waterford 3 (Single Unit Plant)

2. a. The number of indopondant rodundant divisions of Class 1E or safety-related de power for this plant is 2 .

(Include any separato Class 3 E or safety-related de, such as any de dodicated to the diesel generators.)

Disegnaipa The two redundant power divisions are doulgnated the A battery / bus and B battery / bus. There is a third, safety-related de division (designated AB battery / bus) in the plant. Although thin AB division is not " redundant" to the A or 14 divisions, it does provido control power to 1E components which can Lo aligned to the redundant ac divisions.

In addition, the control power for tio breakers (from both redundant ac divisions to the An " swing" bus) and the Emergency Feodwater Pump Turbino controls are fed from the AB de division,

b. The number of functional safety-related divisions of de power nocessary to attain safo shutdown for this unit is 1

Discueplsn Under certain equipment alignments, it is possible for the AB dc division to be supplying control power to components required for safo shutdown of the plant.

Por the W3 FSAR, this division is considcred safety-related.

3. Does the Control Room sit this unit have the following coparato, indopondently annunciated alarms and indications for each division of dc powor?

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a. alarms NOTE: In - the caso of common alarms, an Auxiliary Operator dispatchod to the local panola would identify which of the pooniblo alarm initiatorn had activated the Control Room alarm. Plant Operations Proceduro OP-500-003 ontitled " Annunciator Res ponno Proceduro

-Control Room Cabinot C" providea the operator ,

with possiblo causos of alarms and recommended actions.

1. Dattery disconnect or circuit breaker open? Icn DIEGlD119.D!

Each division of the de power distribution syntom has a common alarm window on control Room Panel CP-35 (1.o. .

window "148" for diviolon "SA" bus, window "!11 0 " for division "SB" bus and window "!!9" for diviulon " SAD" 1:un) ontitled " Battery SA (SB or SAD) Troublo". The alarm in designed to be activated when oither of throo conditiono exists (1) the division battery disconnect switch is ,

opon, (2) a de bus ground exista on the division dc bun, or (3) an unoorvoltsgo condition exista on the diviolon de bus.

2. Battery charger disconnect or circuit breakor opon (both input ac and output de)? Ygg Discussio.D:

Upon opening of a battery chargor circuit breaker (input ac and/or output de), the control Room operator w111 got a common " Battery Charger Troublo" alarm on CP-35 Windowa LB, L9, L10, MB, M9, or M10 (a separato Window for each battery charger, with two battery chargers por de division bus) dependant upon the chargor involved.

3. do System ground? Xca j DitLGMER19.D:

Each division of the de power distribution system has a

ommon alarm window on Control Room Panol CP-35 (i.e.

uindow "N8" for division "SA" bus, wi ndow "N10" for civision "SB" bus and window "N9" for division "SAB" bus) ontitled " Battery SA (SB or SAB) Troublo". The alarm is designed to be activated when either of throo conditions exist: (1) the division battery diaconnect switch in open, (2) a dc bus grour.d oxists on the diviolon de bua, J

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or (3) an undervoltage condition exists on the division  :

do bus. Each load contor has a ground detector relay, 4 5 .

l the de systems operato ungrounded. A ground detector voltmotor is provided in each load center.

4. de bus undorvoltago? Its [

Dinguaoion f Each division of the do power distribution system has its own common alarm vindow on control room Panol CP-35 (i.e. ,

window " 11 8 " for division "SA" bus, window "1110" for ,

division "SD" bus and window "119" for tho " SAD" bus),' l which reads " Battery SA (SD or SAD) Troublo". The alarm 1 is designed to be activated whon either of throo conditions exists (1) the division battery disconnect ,

switch is open, (2) a do bus ground . exists on tho division de buu, or (3) an undervoltago condition exists t on the diviolon de bus. DC bus voltago indication is  ;

available both in the Control Room (CP-1) and at the i local bus panols. -

5. dc bus overvoltago? Iqn D1R M M1.QD:

There-is an overvoltage alarm on each of the two chargers on cach of the de division buson (SA. SD and SAD) on ,

CP-35 in the control Room. Each alarm is a common window (L8, L9, Llo, MB, M9, and M10) ontitled "Dattery Charger (e.g. SA1) Troublo". The overvoltago alarm has shared inputs with the respectivo charger low voltago, no chargo, and ac power failuro alarms. DC --bus voltago motors are hva11able in the control Room (CP-1) and

-locally at the battery chargora.

6. Battery charger failuro? Yea l ningussion:

Control Room Panol CP-35 has an -- alarm window - ontitled "Dattery Charger (u.g. SA1) Troublo" for each of two ['

charf, s on each of the division de buses (SA, SD and SAD). The alarm actuators are high voltage shutdown, low voltago, high voltage, no chargo,-and ac power supply fhilure. <

7. Battery dischargo? Ica ,

Dlacussion:

i Control Room Panol CP-35 common "Dattery Charger Troublo" alarm has an ittput for "no chargo" condition. A local -

charger panel pilot lamp will illuminato to identify tho

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no chargo condition. Under a no chargo condition the de loads on tho affected bun would be nupplied by the battory in a discharging modo. The chargora are equipped with pilot lights that indicato a no chargo condition.

b. Indications

1. Dattery float chargo curront? t(p Dl#C110.R12D*

Indication of battery float chargo current la not provided in thu control room. bocal panol indication 10- provided for this paramotor (DC EM-A3, 11 3 , and A113 ) . Th10 arrangement in considorod adoquato. Oporations performs watchstation curvoillancos, collectin., thin data from the local panol instrumontation on a por shif t bauin fer each battery chargor (DA1, DA2, SDA, SD2, SA111_ and SAD 2) . fho Control 1(oom Supervicor ,

reviewn watchntation logo on a por chift banis por oporationa Inntruction 01-004-000, l'I oa t chargo current is a paramotor that in unoful in normal operating modo. The paramotor in not one that tho- .

operatora nood to havo readily availablo- in an off-normal situation to analyze bun integrity- 4 during an accident. A common alarm window ontitled t "Dattory Chargur (bun identiflor)

Troublo" on control panol Cp-35 in the control Itoom in unod to alort the Control Itoom operators if a failuro ,

occurn on -n battery chargor. This alarm in also activated by the "No Chargo" input from the respectivo chargorn. Thorofore battory float chargo current in adoquatoly monitored without

. Control Room indication.

2. Battory circuit output curront? RQ Dincunajon:

Indication of battery output current :10 not provided in the Control Room. bocal panol indication of- this paramotor (DC-EM-A3, D3, AB3) in provided. This arrangement in connidorod adoquato.

Operations performa watchstation surveillancos, collecting data for this paramotor from the local

.panol instrumentation-on a por chift basin.- The Control Room Supervinor reviews - watchntation- logs on a por ohlf t . banis por Operationn Instruction ,

01-004-000. Alarma . are available to alert the Control Room Operatoro if a failure occurs on a battery charger ("Dattery Charger Troublo") .or if a >

battery djaconnect switch was opon("Dattery Trouble"). DC bun voltago lo available in the

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L Control Room (CP-1) and is the moro critical paramotor to havo readily available sinco it is a measure of the electromotive force available to operato the loads. The syntom can be adoquatoly analysed based on bus voltage readings. Thoroforo, a battery circuit output curront monitor is not necessary in the Control Room.

3. dattery discharge? Hg Discussinn:

Indication of battery dischargo status is not provided in the control Room. Local panel .

Indication of this paramotor is provided. Tho arrangement is considered adequato. " Battery -

discharge" is interpreted here as being a condition wherein de loads are being fed by a de safoty bus battery (charger not availablo). As mentionod above, the Control Room Operator would got a common

" Battery Charger Troublo" alarm on CP-35 windows '

L8, L9, L10, H8, M9, or M10 (a sophrate window for each hattery charger, with two battery chargers por do bus) dependant upon the charger involved.

Thoroforo, battery dischargo is adequately monitored without Control Room indication. The chargern are equipped with pilot lights that indicato a no chargo condition.

4. Bus voltago? Iqa piccussion:

DC bus voltage is indicated in the control Room on CP-1. Also computer points, which oxist for this parameter, are available to the Control Room Operators. l 4 c. Does the unit have written proceduros for response to the above alarms and indicationo? 192 Discuosion:

Operations Proceduro OP-500-003 ontitled

" Annunciator Responso Proceduro control Room Cabinot C" provides: guidanco for responding to annunciator alarms. Also, off-Normal Proceduro OP-901-055 ontitled " Loss of a 125v DC Bus" providos instructions to the operators for handling  ;

asacciated plant conditions.

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4. Does this unit have indication of bypassed and inoperablo ,

status of circuit breakers or other devices that can ba used to disconnect the battery and battery chargor from its de bus ,

and tho battery charger irum its ac power sourco during maintenance or testing? Eca Diaquea1on Upon opening a battery charger circuit breaker (both input ac and output do) for maintenanco or testing purposen, the Control Room Operator will got a common "Battory Chargar Troublo" alarm on CP-35 Windows 1.8, L9, L10, H8, H9, or M10 (a separate window for each battery chargor, with two battery  ;

charguro por dc bus) dependant upon the charger involved.

Each divicion of tho de power distribution nyatom has its own common alarm window on Control Room Panol CP-35 (1.o window

"!!8" for division "SA" bus, window "1110" for division "SB" bun and window "119" for division "SAB" bus) which roada " Battery SA (SB or SAB) Troublo". The alarm in doulgned to be activated when either of throo conditiono exists (1) the division battery disconnect switch in open, (2) a de bun ground exista on the olvision dc bus, or (3) an undervoltago condition exists on- the division dc bus. Thorofore if a battery disconnect were opened for maintenanco or tonting, thin alarm would bo procent in the Control Room. The Control Room also has coparato and indopondent computer point indication of battory disconnect switch status (e.g. D59921 125 VDC Pill 3A-DC-S Battery Disc)

5. If thu answer to any part of quantion 3 or 4 la no, then provido information justifying the existing donign features of the facility's safety-related do syntoms.

Discussion:

Support for existing design featuros adequacy in included 1 under " discussion" for annwora marked "no".

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6. (1) llave you conducted a review of maintenanco and testing activitios to minimizo the potential for human error causing more than ono do division to be unavailablo? len - and (2) do plant proceduros prohibit maintenanco or testing on rodundant de divisions at the camo tino? Len -

Disgussion Waterford 3 has recently comploted a procedurou upgrado program nn operations and maintenance proceduros. Tho upgrado program includod human factors considerations. Resultu of the upgrado offort are discussed in NRC Inspection Report ,

50-382/91-07. .

Watorford 3 controls scheduling maintenanco or testing on redundant de divisions by designating 'A' Train vooks and 'B' Train wooks for routino maintenanco and test activltion. The schedulo is reviewed by Scheduling, ti.o Operaticns coordinator, the operations. Superintendent, and- -the Maintenanco Superintendent. Planning and ncheduling proceduro (PLG-009-007) requires that any work on the schedulo requirity entry into a Technical Specification Action Statomont requiros-approval by the oporations Superintendant or designoo.

Approval is usually obtained at the Plan-of-tho-Day (pod) muoting. The Shif t Supervisor authorizos work and reviews for Technical- Specification applicability and rodundant train operability requirements.

If the facility Technical Specifications have provisions equivalent to thoso found in the Westinghouso and Combustion Engincoring Standard Technical Specifications for maintenanco and surveillanco, then question 7 may be skipped and a statomont to that offect may-be insorted horo. Waterford 3 Technical _S n qilications hate provisigng_qnuivalent to thqpo found in the Coml MD11on 2 IDginggrinti Standard Technical Snocification (NUREG-212) ..

8. Does this plant havo operational features t,uch that following loss of one safoty-related de power supply or bus:

a. Capability is maintained for ensuring continued _ and adequato react,or cooling? Inn -

b. Reactor coolant system integrity and isolation capability are maintainod?- 122-L

a

c. Operating proceduros, instrumentation (including indicators and annunciators), and control functions are adequato to initiate syntoms as requirad to maintain adoquato core cooling? Xg2

9. If tho answer to any part of question 6, 7 or 8 is no, then provido your basis for not performing the maintenanco, survoillanco and tost procedures doacribed and/or the bacon for not including the operational features cited. *Soo note below. (!!oto that answers to questionn 6, 7 and a woro "you")

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