0CAN109106, Responds to Generic Ltr 91-06, Resolution of Generic Issue A-30, 'Adequacy of Safety-Related DC Power Supplies.'

Responds to Generic Ltr 91-06, Resolution of Generic Issue A-30, 'Adequacy of Safety-Related DC Power Supplies.'

ML20085K253
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/25/1991
From:	James Fisicaro ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR 0CAN109106, CAN109106, GL-91-06, GL-91-6, NUDOCS 9110300255
Download: ML20085K253 (11)

Text

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g: - Entcrgy ""av oa 'a"aa '"c-Operations October 25, 1991 OCAN109106 U. S. Nuclear Regulatory Commission Document Control Desk Mail Station P1-137 Washington, DC 20555

Subject:

Arkansas Nuclear One - Units 1 and 2 Docket Nos. 50-313 & 50-368 License Nos. DPR-51 & NFP-61 Resolution of Generic issue A-30,

" Adequacy o f Sa fety-Relat ed DC Powe r Supplies" - Generic Letter 91-06 C

GentIemen:

The NRC Staf f completed the evaluation of Generic Issue (01) A-30 as part of the resolution of Gl-128, " Elect rical Power Reliability." G1 A-30

[

focuses on safety-related de systems. As a result of this evaluation, the Staf f dott rmined that cert ain maintenance, surveillance, and '

monitoring provisions are appropriate for safety-related de systems. The Staff believes that most plants have already implemented most of these provisions because of a number of actions taken previously by the Staff and the industry.

Generic Letter (GL) 91-06 (dated April 29, 1991) provided the results of the NRC's evaluation of the generic issue and requested licensees to provide written responses to the questions provided in Enclosure 1 of the GL.

This submittal provides the requested responses for Arkansas Nuclear One, Units 1 and 2 (ANO-1 & 2). The ANO-1 & 2 specific responses are provided in Attachments 1 and 2, respectively.

In accordance with the requirements of GL 91-06, this letter is being signed under oath. Should you have any questions regarding our' response to this issue, please contact me.

Very truly yours, f,, ~<. )5%

(amos . FisIcaro Director, Licensing JJF/RWC/sjf 1 Attachments I

A\ l I

91103002b5 Y110D n~ PDR ADOCK 05000313 (

4a p PDR

U. h. NRC October 25, 1991 Page 2 cc: Mr. Robert Martin D. S. Nuclear Regulatory Com.alssion Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Resident inspector g Arkansas Nuclear Une - ANO-1 6 2 Number 1, Nuclear Plant Road Iussellville, AR 72801

, Mr. Thomas W. Alexion NRR Project Mannger, Region IV/ANO-1 U. S. Nuclear Regulatory Commission NRR Mall Stop ll-D-23 One White Flint North

( 11555 Rockville Pike Rockvilln, Maryland 20852 Ms. Sheri Peterson NRR Project Manager, Region IV/ANO-2 U. S. Nuclear Regulatory Commission NRR Mai1 Stop 11-D-23 One White Tilnt North 11555 Rockv111n Pike Rockville, Maryland 20852

. 'STATE OF ARKANSAS )

) SS COUNTY OF 1,0GAN )

'1, James J. Fisicaro, bning duly sworn, subscribe to and say that I am Director, l.icensing at ANO for Entergy Operations, that I have full authority to execute this af fidavit; tha' I have road the document numbered OCAN109136 and know the contents thereof; and that to the best of my knowledge. Information and belief the statements in it are true, tw h.bAL4.~

Jamesf). Fisicaro SUBSCRIBED AND SWORN TO beforo me, a Notary I'ublic in and for the County and State above named, this _ _ day of ,

1991.

Notary Public My Commission Expirns:

?

4

.- ATTACitMENT 1

, 1. ' Unit ANO-1

2. a. The number.of independent redundart divisions of Class IE or safety-related de power for this plant is TWO. (include any separate Class 1E or sa fety-related de, such as ar1y de dedicated to the diesel generators.)

b. The number of functional safety-related divisions of de power necessary to attain safe shutdown for this unit is ONE.

3. . Does the control room at this unit have the following separate, independently annunciated alarms and judications for each division of de pcwor? ,

a. alarms 1-. Battery disconnect or circuit breaker open? YES (Multipoint Alarm) ,

2. Battery charger disconnect or circuit breaker open (both input ac and output de)? YES (Multipoint Alara)

3. de system ground? YES (Multipoint Alarm)

L 4. de bus undervoltage? YES

5. de bus overvoltage? YES (on SPDS)

6. Battery charger failure? YES (Mu'itipoint Alarm)

7. Battery discharge? ND

b. Indications 1, Battery float char; current? NO

2. Battery circuit output current? -NO

3. Battery discharge?. NO

4. Bus voltage? YES (on SPDS)

c. Does the unit have written procedures for response to the above alarms and indications? YES

4. Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect the

-battery and battery charget from its.dc bus and the battery charger-from

-its'ac power source during maintenance or testing? YES

f, . If the answer to any pntt of question 3 or 4 is no. then provido in.

. formation justifying the existing design features of the Pellity's '

safety-related dc systems. *Sco note below.

3 ad Although battery discharge is not specifically annunch tad in the 3

control ro,)m, the operators have alnres which will indicate when the battery is discharging. -

4 l' the battery is discharging due to loss of AC poser or battery charger fa.11 ore, the control room operators will receive alarms that the battery charger in disconnected or the circuit breaker is oper, and that the charger has failed.

If the battery begins to discharge because the load exceeds the corrent supplying capacity of the battery charger. then the de bus must be at 116 Vdc or below sin,e this is the terminal voltage of the battery. This condition is annunciated in the control room.

3.b J: An ammeter is located on the battery chntgert however, the scale is not adequate to accurately read small float charge currents. Control room float current indication is 1,ot necessary since the condition of the battery is ensured by recording pilot cell voltage, temperature, and specific gravity and the overr.11 battery bank voltage on a daily basis as required by Technical Specification 4.6.2.

3.b.2: The lentication of the battery circuit output current is provided by n -

local ammeter. Local indication is sufficient with the control room alarms described in 3.a above and the daily surveillance procedure required for these battery banb hb.3r Although there is no specific battery discharge indication in the control room, an alarm which alerts tbs operators when the battery bank is beginning to discharge is provided as described in response to question 3.a.7.

The operators can then monitor the local ammeters and voltmeters and the bus voltage indication in the control room as necessary.

6. (1) llave you conducted a review of maintennnce and testing activities to minimize the potential for human error causing more than one de division to bn unavailable? NO and (2) do plant procodores prohibit maintenanen or testing on redundant de divisions at the same time? YES  !

11 the facility Technical Specifications have provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specification for maintenance and surveillance, then question 7 may bn skipped and a statemont to that offect mny be inserted horn.

NOT APPLICABLE t

l.

I l

,7.. Aro maint erwocn, s,'irvellinnre and t est procoduren r egarding stat ion ,

, batterien conducted tuntinely /it this plant? Speciffently

n. At Ice enco par 7 days, are ihn following verified to he ,

within are.vtabir I Nits;

1. "; tot c Ii c1 ict rolyte levol? YES r

? -er 4

• 4c gravit y nr chntging e ntrent ? YES

3. I'lont voltage? YES

4. Total bus voltagn on float charge? YES 5 Physient condit ion of all cells? YES  :

b. At lennt once per 92 dnya, or withlei 7 dayn af ter a battety  ;

dischargo, overchargo, or if the pilot coll rendingn are outside the 7-day survoillance requirements nro the following '

verified to be within acceptablo limita: (Sco number 7.b under question 9)

1. Electrolyto level of-cach coll? YES

2. The averngn specific gravity of all celln? YES

3. The specific gravity of _ eneti coll? TES

4. Tho averngn electrolyte t emperat urn of a reprencatat ive numb.ir of calls? YES i

5. The float voltage of ench en117 YES i

6. Visually innpect or mensurn renistanco of toiminnin and I connectorn (including the connectorn at the de bus)? YES ,

c. At least nyery 18 months, are the following verified:

1. l.ow resistance of each connection (by test )? YES I

2. Physical condition of t he b:tt ery? ; YES i 3.11nttery charger capability to deliver its design duty cycle to the de bus? YES

4. The capability of thn batacry to deliver its design duty cycle to the de bon? NO-l S. Ench individual' coll volingo in within acceptable limitn during thn nervice test? N0

d. At least nyery 60 months, in capacity of each batt ery vert fled by performance of a discharge test? YES

e. At innat annually, in thn hattery capacity vnrified by per-formance dischargo tent , if the hatt ery shows signs of de- _

i_

gradation or has reached 85*. of the expected service lifo? 8 l NO_

l l

e *- em +' --M-ree---e, _+e.c.,r---,e+-

amem ,,rs w y-e, v y ma r r -

• t- t"i r e-* sween----r*==r-<-m-ew- sw e 'e= g n---wv & ew 1 e w.-m e e -w--w w e 's m 't w r+

• r - wt e mn-ye ry ..r--+m r

• c

,8 . Doca this plant have operat ional f ontur es such t hat following loss of one safety-related de power supply or bon:

a. Capabilit y is maintained for ensuring continued and adequate reactor cooling? YES

b. React or coolant system totegrity and isolnt ton onpnbility are mnintained? YES

c. Opetating procedures, inst t ument at ion (including indicator s and annuncintors), and contr01 funttions nre adequntr to initiate systems as required t o maint ain adequat e core cooling? YES 9 If the answer t_ my part of question 6, 7 or f. is no, then provide your basis for not onr f orening t he rnnint enance , surveillance and test procedures dest si i and/or the bases for not including the operationnt f eat ures cited. *H , note below.

6.(1): Although no specific documented review for this purpose han been recorded, ptocedures that involve taking a redundant de divinfon out of service do contain ateps to verify the opposite train is in service prior to beginning the maintenance activity.

7_. b Concerning battery "overchargo" referred to in thin question, this condition is not referred to, an such, in ANO-1 proceduren. Ilowever, a proceduro doen address the condition when the battery bank voltage in abovn the Technical Specificat ion limit and specif f en correcti e nilonn in accordeaco with other procedurcs.

7.c_.4 and 5: ANO-1 Technical Specifict, tion 4.6.2.3 staten, " Onco every eighteen months, a performance discharge test shall be conducted in accordance with the manufacturer's instructions, for the purpose of determining battery capacity." ANO-1 is preparing a change request to the Technient Specifications to incorporate the appropriato Standard Technient Specifications that will include the surveillance requirement identified in item 7.c.4. This change request is currently scheduled to be submitted by June 30, 1992.

7 o: This surveillance 19 performed ovory eighteen months as specified in ANO-1 Technien1 Specifications 3.7.1.D, 3.7.2 F, and 4.6.2.3.

Additionally, ANO battery surveillanco proceduren staten, "If the enpacity eniculated is less than 907., then notify Maintenanco Engincoring for evaluation."

• Not e : For quest ions involving support ing type information (question numbers 5 and 9) in%t end of developing and supply tt;g t he informction in responsn to this letter, you may commit to further evalunte the need for such provisions during the per f ormance of your trulividuni plant examination for severo accidont vulnernbillt les (lpE). If you select thin option, you are required to:

(1) So state in response to these questions, and (2) Cornm i t to explicitly addrnss questfons 5 nnd 9 in your lpE submittal per the guidelines outlined in NUKEG-1335 (Sect ion 2.1.6. Subitem 7). "Individuni plant Examinntion: Submittal Guidance".

i

, ATTAtllMENT 2 ,

1. -Unit ANO-2

2. a. The number of independent indundalit divisions of Class 10 or safoty-related de power for this plant is TWO. (includo any separato Class IE or safety-related de, such as any de dedicrted to the dicsol generators.)

b. The number of funct ional saf ety-t einted divisions of de power necessnry to attain safo shutdown f or t his unit is ONE.

1. Does the control room at this unit have the following separat e, independently annuncleted alarrns amt indications for each division of de power?

h. alarma

1. Battery disconnect or circuit breaker open? YES

2. Battery charger disconnect or ciscuit breaker open (both input ac and output de)? YES (Hultipoint Alarm)

3. de system ground? YES

4. de bus undervoltage? YES

5. de bus overvoltago? YES (Multipoint Alarm)

6. Battery charger failure? YES (Hultipoint Alarm)

7. Battery discharge? NO

b. Indications

1. Battery float charge current? NO

2. Battery circuit output current? NO

3. Battery discharge? NO

4. - lius valtngn? YES (on SPDS)

c. Does the unit have written proceduren for responso to thn abovo alarms and indications? YES

4. Does this unit havn indiention of bypassed and inoperabln status of

. circuit bronkers or other devices that can be used to disconnnet thn battery and bat. tory charger from its de bus and the battery charger from its ac power sourco during maintenance or testing? YES (ace number 4 under question 5)

.- , ., r ._

,5. If the answer to any part of quest ion 3 or 4 is no, then provide in-i formation jurtiiving the exist ing design features of the f acility's saf et y-reint ed dc syst ems. *See note holow.

3.a.7 Although battery discharge is not specifically annunciated in the control room, the operators have alarms which will indicate when the battery is discharging.

If the battery in discharging due to loss of AC power or battery charger (silure, the control room operators will recolve alarms that the battery cnarger is disconnected or the circuit breaker is open and that the charger has failed.

If the bsttery begins to diechargo becaus,c the load exceeds t he current supplying capacity of the bat tery charger, then the de bus must be at 116 Vdc or below since this in the terminal voltage of the battery. This condition is annunciated in the control room.

3.b.1: Control room float current indication is not necessary sinco the parameters monitored in the wockly surveillances required by Technical Specification 3/4.8.2.3 are considered to be adequate.

3.b.2: The indiention of the bat tory circuit output current is provided by a local ammetet. Local indication is sufficient with the conttol room alarms described previously and the surveillance procedure required for these battery banks.

hb.3: Although there is no specific battery dischargo indication in the control room, an alarm which alerts the operators when the battery bank is beginning to dischargo la provided as described in responso to question 3.a.7. The operators can then monitor the local ammeters and voltmotors and the bus voltage indication in the control room as necessary.

_4_ : The exception to this responso in that the battery charger feedor breaker to the de bus is not alarmed. An alarm is provided in the control room if the battery safety disconnect switch is open or if the battery fuso is blown or removed and an additional alarm is provided in the control room if the ac battery charger input or de output breaker is open. Even though there is not an alarm in the control room in the ovent the de bus feeder breaker from the charger is open or tripped, this conditim will be detected during periodic surveillance of the battery / charger system or if the bus voltago drops to the low voltage alarm setpoint of 110 Vdc.

6. (1) linve you conduct ed a review of maint enance and testing act ivit ies to minimize the potential for human error causing more than onn de division to be unavailnble? NO and (2) do plant procedures prohibit maint enance or testing on redundant de divisions at the same time? YES If the incilit y Technient Spect ricationn have provisions equivalent to those found in the Westinghouse and Combustion Engineciing Standard Technical Specification for maintennnee and surveillance, then question 7 may bn skipped and a statement to that effect may be inserted here.

NOT APPh1 CABLE

Arn anintenance, sur veilletico nin1 t est procedures regarding sintion 7.

bat teries coiniucted rout inety at this plant? Specifically:

n. At least once per 7 days, ora the following vertiled to be within acceptable limits:

1. Pilot cell electrolyte leve l Tr YES

2. Specific gravity or ohniging current? YES

3. Float voltage? YES I

4 Total bus voltage on float charge? YES

5. Physical condition of all cells? YES

b. At lenst once per '.72 days, or within 7 days af t er n bnt t er y dischargo, overcharge, or if the pilot cell rendingn are ou t s ide the 7-day surveillance requirements, are the following verified to be within acceptablo limits:

1. Electrolyte level of each cell? YES

2. The averagn specifft gravity of all cells? YES

3. The specific gravity of each cell? YES

4. The nyerngo electrolyte temperature of a representntIvo number of colis? YES

5. The ilont voltngn of ench cell? YES 6 Visually inspect or mensure resistance of terminals and connectors (including the connectors at the dc bus)? NO

c. At least overy 18 months, nrn the following verified:

1. how resist ance of each connection (by t est )? YES

2. Physical condition of the battery? YES

3. Battery charger capability to deliver its design duty cycle to the de bus? YES

4. Thn capability of the bat tery to deliver its design duty cycle to the de bus? YES

5. Each individual cell voltago is within acceptable limits during thn servi,co test? N0

d. At least every 60 month,i, is capacity of ench bat t ery verified by performance of a dischargo test? YES

e. At 1 cast annutolly, is the battery capacity verified by per-formance dischargo test, if thn battery shows signs of dn-gradation or has renched 85%, of thn expected service life?

NO

8. Doon this pinut have opnratfunn! featutes such that following loss

. of one safety-related de power supply or bus t J i, a. Capability is mai 'nined for ensuring cont inued and adequat o redctor cooling? u.S

b. Ronctor coolant systern int egrit y and isolat ion capnhilit y ,

are maintained? YES '

c. Operating procedures, instrumentation (including indientons and gununciators), and ront rol f unct ions nie adequat e t o initiate systems as required to maintain adequnto core cooling? YES

9. If the answer to nay part of quest ton 6. 7 or 8 is no, then provide your basis for not per forming the maintennnco, surveillance nint test procedures described and/or the bnses for not including the operat ional features cited. *Sco not o below. '

6d}): Although no specific documented review for this purpose has bocn ,

recorded, procedures that involve taking a redundant de division out of '

service do contain steps to verify the opposite t rain is in service prior to beginning thu maintenance activity.

7.b.6 Resistance measurements on inter-cell and inter-tier connections are taken as well as the connections at the batteries which lend to the busca, llowever, resistance measuremn'.ts or visual inspections are not performed on the connectors at the buses themac1ves. The buscs are located in a separate room from the battories and are not subject to the same corrosive environment as that potentially created in the battery rooms.

7.c.5: The total battery bank voltago is surveyed just prior to cach duty cycle change.

Les This surveillanco is performed every eighteen months as speciflod in '

ANO-2 Technical Specification 4.8.2.3.f.

• Noint 1"or quest ions involving supporting type information (question numbers 5 aad 9) instead of devnloping niul supplying the information in '

response to this letter, you may commit to furt.hnr evalunto the need for such provisions during the performance of your individual plant examinintion- for severe accident vulnernbilit les (lpE), If you select this option, you are required to:

(1) So stato in response to these questions, and (2) Commit to explicit ly address questions 5 and 9 in your IPE submit tal por the guidelines out lined in NUREG-1335 (Section 2.1.6. Subit em 7), " Individual Pinnt Examination: Submittal Guidance".

.. - _ _