ML17329A227

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

ML17329A227
Person / Time
Site:	Cook
Issue date:	10/28/1991
From:	Fitzpatrick E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR AEP:NRC:1152, GL-91-06, GL-91-6, NUDOCS 9111040187
Download: ML17329A227 (19)

Text

ACCELERATED DISTIGBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9111040187 DOC.DATE: 91/10/28 NOTARIZED: YES DOCKET g FACIL:50-315 Donald C. Cook Nuclear Power Plant, Unit 1, Indiana M 05000315 50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana M 05000316 AUTH. NAME AUTHOR AFFILIATION FITZPATRICK,E. Indiana Michigan Power Co. (formerly Indiana 6 Michigan Ele RECIP.NAME RECIPIENT AFFILIATION R MURLEY, T. E. Document Control Branch (Document Control Desk)

I

SUBJECT:

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

DISTRIBUTION CODE A001D COPIES RECEIVED:LTR ENCL t SIZE / ~

TITLE: OR Submittal: General Distribution NOTES RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD3-1 LA 1 1 PD3-1 PD 1 1 COLBURN,T. 2 2 D INTERNAL: NRR/DET/ECMB 7D 1 1 NRR/DET/ESGB 1 1 NRR/DOEA/OTSBll 1 1 NRR/DST 8E2 1 1 NRR/DST/SELB 7E 1 1 NRR/DST/SICB8H7 1 1 NRR/DST/SRXB 8E 1 1 NUDOCS-ABSTRACT 1 1 OC/LFMB 1 0 OGC/HDS2 1 0 RE~FXZE ~01 1 1' RES/DSIR/EIB 1 1 EXTERNAL RC DR 1 NSIC 1 1 R

D D

D NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 18 ENCL 16

Indiana Michigan Power Company P.O. Box 16631 Cotumbus, OH 43216 AEP:NRC:1152 Donald C. Cook Nuclear Plant Units 1 and 2 Docket Nos. DPR-58 and DPR-74 License Nos. 50-315 and 5-316 RESPONSE TO NRC GENERIC LETTER 91-06; RESOLUTION OF GENERIC ISSUE A-30 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Attn: T. E. Murley October 28, 1991

Dear Dr. Murley:

This letter provides our response to NRC Generic Letter (GL) 91-06, Resolution of Generic Issue A-30, "Adequacy of Safety-Related DC Power Supplies." The GL requests information regarding the plane-specific maintenance, surveillance, and monitoring provisions for the DC power system. This information is provided in the attachment to this letter.

As requested in the GL, our response is being submitted under oath according to the provisions of Section 182a of the Atomic Energy Act 1954, as amended, and 10 CFR 50.54(f).

Sincerely, E. E.

pm Fitzpatrick Vice President ldp Attachment 9X11040187 911028 PDR ADOCK 05000315 P PDR

Dr. T. E. Murley AEP:NRC:1152 cc: D. H. Williams, Jr.

A. A. Blind J. R. Padgett G. Charnoff A. B. Davis - Region III-NRC Resident Inspector Bridgman NFEM Section Chief

COUNTY OF FRANKLIN Eugene E. Fitzpatrick, being duly sworn, deposes and says that he is the Vice President of licensee Indiana Michigan Power Company, that he has read the foregoing Response to NRC Generic Letter 91-06; Resolution of Generic Issue A-30, "Adequacy of Safety-Related DC Power Supplies" and knows the contents thereof; and that said contents are true to the best of his knowledge and belief.

Subscribed end sworn to before me this ~P+ 'I )%s ~P Wii '$

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day of 199~. p ~i) Q NOTARY PUBLIC RITh D. HILL ROTARY PUBLIC. STATE OF OHIO

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Attachment to AEP:NRC:1152

AEP:NRC:1152 ENCLOSURE 1 page 1 of 9 10 CFR 50.54(f) REqUEST - GENERIC ISSUE (GI) A-30 "ADEQUACY OF SAFETY-RELATED DC PObfER SUPPLIES" Back round The specific area of concern of GI A-30 "Adequacy of Safety-Related DC Power Supplies" is the adequacy of the safety-related dc power in operating nuclear power plants, particularly with regard to multiple and common cause failures.

Risk analysis and past plant experience support conclusions that failure of the dc power supplies could represent a s igni f icant contribution to the unreliabi i ty 1 of shutdown cooling. Analysis indicates that inadequate maintenance and survejjlance and failure to detect battery unavailability are the prime contributors to failure o the dc power systems.

During the develooment of plans to resolve GI A-30, it was observed that several previous'.y issued regulatory notices (IElls), bulletins (IEBs) and letters (GLs) submitted to license s include recommendations similar to those that have been identified to resolve GI A-30. More specifically, it has been determined that recommendations contained in notifications IEH 85-74, 'Station Battery Problems", IEB 79-27, "Loss of Non-Class 1E Instrumentation and Control Power System Bus during Operation," and separate actions being taken to resolve GI 49, "Interlocks and LCOs for CIass 1E Tie Breakers" include the elements necessary to resolve GI A-30. It '.s therefore concluded that licensees that have implemented these recommerdations and ac.ions will have resolved GI A-30.

The response to the ques .ons that ollow is necessary to provide the staff with information to determine whether any fur.her ac:;on is reouired '.or your faci 1 i ty.

Oues ti ons The following in;ormation is 'to be provided for each unit at each site:

Uni t QNE

2. a. The number of independent redundant divisions of Class 1E or safety-related dc power for this plant is TwQ er UNIT (Include any separate Class 1E or safety-related c, sucn as any dc dedicated to the diesel generators.)

b. The nuirber of functional safety-related divisions of dc power necessary to attain safe shutdown for this unit is QNE

3. Goes the control room at this unit have the following separate, independently annunciated alarms and indications for each division of dc power?

a. alarms

1. Battery disconnect or circuit 'breaker open?

2. Battery charger disconnect or circuit breaker open (both input ac and output dc)? vEs

2

~P: NRC: 1152 page 2 of 9 n

3. dc system ground? YES YES 4 ~ dc bus undervoltage?

5. dc bus overvoltage? YES

6. Battery charger failure? YEs 7, Battery discharge? see Note 1, page 9 of 9

b. Indications

1. Battery 'lOat Charge Current? See Note 1, page 9 of 9

2. Battery circuit cutput current? see Note 1, page 9 of 9

3. Battery diSCharge? See Note 1, page 9 of 9

4. Bus voltage? YES

c. Does the unit have written procedures '.or 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

'at.ery and bat:ery charger from its dc bus and the battery charger f.om itS aC pOWer SOurCe during maintenanCe Or -.eSting? See N<<e 2 page 9 o

5. If the answer to any part of question 3 or 4 is no, then provide information

'ustifying the existing design features of the facility's safety-related dC SyStemS. See nOte belO~. See Note 3, page 9 of 9..

6. (I) Have you conducted a revie~ of maintenance and testing act',vitfes to minimize the potential for human error causing more than one dc division b lb1 and (2) do plant procedures prohibit maintenance or testing on recunaant dc divisions at the same time?

YES If the facility Technical Specifications have provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specificati for maintenance and surveillance, then question 7 may be skipped and a statement to that effect may be inserted here. n/a =

7. Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:

a. At least once per 7 days are the following verified to be within acceptable limits:

1. Pilot cell electrolyte level? YES

3 AEP:NRC:1152 page 3 of 9 5p~cific gravity or charging current?

Float voltage? Yes

4. Total bus voltage on float charge? YES

5. Physical condition of all cells? YES

b. At least once pet 92 days, or within 7 days after a battery discharge overcharge, or if the pilot cell readings are outside the 7-day surveillance reauirements are the following verified to be within acceptable limits:

l. Electrolyte level of, each cell? YES

2. The average specific gravity of all cells?

3. The specific gravity of each ceIl?

4. The average electrolyte temperature of a representative number of cells?

5. The float voltage of each cell? YEs

6. Visually inspect or measure resistance of terminals and connectors (including the connec::rs at the dc bus)?

YES

c. At least every 18 months are the follcwing verified:

1. Low resistance of each connection (by test)? YEs

2. Physical condition of the battery?

3. 8attery charger capability to deliver rated ampere output to the dc bus?

4. The capabi lity of the battery to deliver its design duty cycle to the dc bus?

5. Each individual cell voltage is wi,thin acceptable limits during the service test? YES

d. At least every 60 months, is capacity of each battery verified by performance of a discharge test? YES

e. At least annually, is the battery capacity verified by performance discharge test, if the battery shows signs of degradation oc has hd Big f h p d < iaaf

AEP:HRC:1152 page 4 of 9 Does this plant have operational features such that following loss of one safety-related dc power supply or bus:

a. Capabflfty fs maintained for ensuring continued and adequate reactor cooling? YES b, Reactor coolant system integrity and isolation capability are maintained?

YES

c. Operating procedures, instrumentation {including indicators and annuncfators), and control functions are adequate to initiate systems as requi red to maintain adequate core cooling? YEs

9. If the answer to any part of question 6, 7 or 8 is no, then provide your basis for not performing the maintdnance, surveillance and test procedures described and/or the bases for not including the operational featureS Cited. *See nOte belOW. See voce 5, page 9 of 9

<<Note: For questions involving supoorting type information (question numbers 5 and 9) instead of developing and supplying the information fn response to this letter, you may commit to further evaluate the need for such provisions during the performance of your individual plant examination for severe accident vu lnerabilitfes ( IPE). If you select this option, you are required to:

{'.) So state fn response to these auestfons, and (2) Coamft to explicitly address questions 5 ana 9 in your IPE submittal per the guidelines outlined in YUREG-1335 ',Section 2. 1.6, Subitem 7),

"Indfvidual Plant Examination: Submittal Guidance."

AEP:NRC:"1152 ENCLOSURE 1 page 5 of 9 10 CFR 50 '4(f) REQUEST - GENERIC ISSUE (GI', A 30 APEqUACY PF SAFETY-RELATED PC POKER SUPPLIES'ack round The specific area of concern of GI A-30 "Adequacy of Safety-Related DC Power Supplies" is the adequacy of the safety-re>ated dc power in operating nuclear power plants, particularly with r egard to multiple and common cause failures, Risk analysis and past plant experience suoport ccnclusions that failure of the dc po~er supplies could represent a significant contribution to the unreliability of shutdown cooling. Analysis indicates that inadeauate maintenance and surveillance and failure to detect battery unavailability are the prime contributors to failure o the dc power systems.

During the develooment of plans to resolve GI A-30, it was observed that several previous'.y issuea regulatory notices (IE.'Is), bulletins (IEBs) and letters (GLs) submitted to licensees include recomendations similar to those that have been identified to resolve GI A-30. More specifically, it has been determined that recommendations contained in notifications IEH 85-74, 'Station Battery Problems", IEB 79-27, "Loss of Non-Class 1E Instrumentation and Control Power System Bus during Operation," and separate actions being taken to resolve GI 49, "Interlocks and LCOs for C'iass 1E Tie Breakers" include the elements necessary to resolve GI A-30. It is therefore concluded that licensees that have implemented these recommerdations and ac.ions will have resolved GI A-30.

The response to the ques"..ons that ollow is necessary to provide the staff with information to determine whether any fur.her .= .on is reouired for your faci 1 i ty.

Ouestions The following in;ormation is to be provided for each unit at each site:

l. Uni t

2. a. The number of independent redundant divisions of Class 1E or safety-related dc power for this plant is mo <<UNzT . (Include any separate Class 1E or safety-related c, sucn as any dc dedicated to the diesel generators.)

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

3. Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of dc power?

'a. a 1 arms

1. Battery disconnect or circuit breaker open?

2. Battery charger disconnect or circuit breaker open (both input ac and output dc)? YEs

4 2

MP:NRC:al52 page 6 of,9

3. dc system ground? YES 4 dc bus undervoltage?

5. dc bus overvoltage? YES

6. Battery charger failure? YEs

7. Battery diSCharge? See Note 1, page 9 of 9

b. Indications

1. Bat.ery flOat Charge Current? See Note l, page 9 of 9

2. Battery CirCuit output Current? See Note 1, page 9 of 9

3. Battery diSCharge? See Note l, page 9 of 9

4. Bus voltage? YES

c. Does the unit have written procedures '.or response to the above alarms and indications? YEs

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

'at.ery and bat.ery charger from its dc bus and the battery charger from itS aC pOWer SOurCe during maintenanCe Or 'eSting? See No<< 2

~

5. If the answer to any part of question 3 or 4 is no, then provide information

'ustifying the existing design features of the facility's safety-related dC SyStemS. See nOte belOW. See Note 3, page 9 of 9

6. (1) Have you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one dc division b il b1 . 1 (2) d p1 " P d p hibi maintenance or testing on reaundant dc divisions at the same time?

YES If the facility Technical Specifications have provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specificat',

for maintenance and surveillance, then question 7 may be skipped and a statement to that effect may be inserted here. n/a

7. Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:

a. At least once per 7 days are the following verified to be within acceptable limits:

1. Pilot cell electrolyte level? YES

3 AEP:NRC:1152 page 7 of 9 Specific gravity or charging current? YEs

3. Float voltage? YEs Total bus voltage on float charge? YES

5. Physical condition of all cells? YEs b.. At least once per 92 days, or within 7 days after a battery discharge overcharge, or if the pilot cell readings are outside the 7-day surveillance requirements are the following verified to be within acceptable limits:

1. Electrolyte level ef each cell? YES

2. The average specific gravity of all cells?

3. The specific gravity of each cell?

4. The average electrolyte temperature of a representative number of cells?

5. The float voltage of each cell? YEs

6. Yisually inspect or measure resistance of terminals and connectors (including the connec:=rs at the dc bus)?

YES

c. At 'breast every 18 months are the follcwing verified:

1. low resistance of each connection (by test)? YES

2. Physical condition of the bat:ery?

3. Battery charger capability to deliver rated ampere output to the dc bus?

4. The capability of the battery to deliver its design duty cycle to the dc bus?

5. Each individual cell voltage is within acceptable limits during the service test? YEs =

d. At least every 60 months, is capacity of each battery verified by performance of a discharge test? YEs

e. At least annually, is the battery capacity verified by performance discharge test, hd8IK ttlif the battery shows signs of degradation or has p ~ i iaaf'I

AEP:NRC:1152 page 8 of 9 poes this plant have operational features such that following loss of one safety-related dc power supply or bus:

a. Capability fs maintained for ensuring continued and adequate reactor cooling? YES

b. Reactor coolant system integrity and isolation capability are maintained?

YES

c. Operatfng procedures, instrumentation (including indicators and annuncfators), and control functions are adequate to initiate s stems sy e as required to maintain adequate core cooling? YEs

9. If the answer to any part of question 6, 7 or 8 is no, then provide your basis for not performing the mafntdnance, surveillance and test procedures described and/or the bases for not including the operational featureS Cited. See nOte belOW. See Note 5, page 9 QQ 9

• Note: For questions involving supporting type information {question numbers 5 and 9) instead of developing and supplying the information fn response to this letter, you may coamit to further evaluate the need for such provisions during the performance of your individual plant examination for severe accident vulnerabil fties (IPE). If you select this option, you are required to.

'( I) So state fn response to these ouestfons, and (2) Comnit to explicitly address questions 5 and 9 in your IPE submittal per the guidelines outlined in AUREG-1335 (Section 2. 1.6, Subitem 7),

"Individual Plant Examination: Submittal Guidance."

~ ~ ~

~

AEP:NRC:1152 page 9 of 9 Note 1: Monitored locally at the Battery Control Panel.

Note 2: There are no bypass features for the battery isolation fuses or the battery charger AC and DC circuit breakers.

As stated in Question k3, alarms exist in the control room that would indicate if the battery isolation fuses were pulled or if the battery charger AC or DC circuit breakers were open.

All inoperable DC related equipment (circuit breakers, fuses, etc) is logged in the "Open Items Log" maintained in the Control Room.

Note 3s There is no indication or alarm for battery input/output current or battery discharge in the Control Room. The status/condition of the battery is monitored utilizing the following:

a~ Battery disconnect or circuit breaker open alarm.

b. DC system ground alarm.

c ~ DC bus undervoltage alarm.

d~ DC bus overvoltage alarm.

e. Routine tours and monitoring of the batteries, the battery control panels (which have indication of battery float charge current, battery circuit output current and battery discharge) and the battery charger control panels.

Note 4: A battery service test is performed at least once per 18 months, coincidental with the plant's planned outages.

Our engineering practice mandates battery replacement approximately every 10 years. Zn addition, D. C. Cook Nuclear Plant Technical Specifications include Limiting Conditions of Operation which require immediate corrective action if the battery shows signs of degradation.

Note 5: See Question $ 7.e. and Note 4. The 18 month service test, along with the regular maintenance the batteries receive, and the Technical Specification requirements for operation, satisfies and exceeds the intent of Question

$ 7.e. (i.e., the battery is not permitted to reach a degraded state or 85% of it's expected service life).

1 ~