ML17306A246

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

ML17306A246
Person / Time
Site:	Palo Verde
Issue date:	10/25/1991
From:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR 161-04240-WFC-G, 161-4240-WFC-G, GL-91-06, GL-91-6, NUDOCS 9111050104
Download: ML17306A246 (25)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9111050104 DOC.DATE: 91/10/25 NOTARIZED: YES DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME AUTHOR AFFILIATION CONWAY,W.F. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIQ.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

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

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: General Distribution NOTES: STANDARDIZED PLANT 05000528 Standardized plant. 05000529 Standardized plant. 05000530 D

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 TRAMMELL,C 2 2 THOMPSON,M 2 2 INTERNAL: ACRS 6 6 NRR/DET/ECMB 7D 1 1 NRR/DET/ESGB 1 1 NRR/DOEA/OTS B 1 1 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 1 0 OGC/HDS1 1 0 F 01 1 1 RES/DSIR/EIB 1 1 EXTERNAL: NRC PDR 1 1 NSIC 1 1 NOTES: 1 1 D

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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 27 ENCL 25

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Arizona Public Service Company P.O. BOX 53999 ~ PHOENIX, ARIZONA85072<999 WILLIAMF. CONWAY EXECUTIVE VICE PRESIDENT 161-04240-WFC/GAM NUCLEAR October 25, 1991 Docket Nos. STN 50-528/529/530 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station Pl-37 Washington, D.C. 20555

Dear Sirs:

Sub) ect: Palo Verde Nuclear Generating .Station.(PVNGS)

Units 1, 2, and 3 Response to Generic Letter 91-06, "Resolution of Generic Issue A-30, "Adequacy of Safety-Related DC Power Supplies," Pursuant to 10 CFR 50.54 (f)"

File: 91-010-026; 91-056-026 Enclosed with this letter is the Arizona Public Service Company (APS) response to Generic Letter 91-06, "Resolution of Generic Issue A-30, "Adequacy of Safety-Related DC Power Supplies," Pursuant to 10 CFR 50.54 (f)." This response is being submitted to the NRC under oath or affirmation.

Should you have any questions regarding this submittal, please contact Michael E. Powell of my staff at (602) 340-4981.

Sincerely, WFC/GAM/gam Enclosure cc: J. B. Martin D. H. Coe A. C. Gehr A. H. Gutterman 9iii050104 9ii025 PDR ADOCK 05000528 P*

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161-04240-WFC/GAM Octobe" 25 1991 STATE OF ARIZONA )

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COUNTY OF MARICOPA )

I, W. F. Conway, represent that I am Executive Vice President Nuclear, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority to do so, that I have read such document and know its contents, and that to the best of my knowledge and belief, the statements made therein are true and correct.

W.. F. Conway Sworn To Before Me This 8 Dey Of C 1991.

"No.tary Public e

Hy Commission Expires

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RESPONSE TO GENERIC LETTER 91-06 UESTION RESPONSE The following information is to be provided for each unit at each site:

1. Unit: PVNGS All three PVNGS units are essentially identical, and the Units 1,2&3 information provided herein is applicable to all three units.

2. a. The number of independent Two There are two independent redundant divisions (load groups) of redundant divisions of Class Class IE or safety-related DC power. Each load group is IE or safety-related DC comprised of two subsystems. The two DC load groups are power for this plant is: identified in the PVNGS Technical Specifications, Table 3.8-1 as (Include any separate Class Trains A and B. This configuration is graphically shown in the IE or safety-related DC, such PVNGS UFSAR Figure 8.3-4.

as any DC dedicated to the diesel generators.)

b. The number of functional One The PVNGS UFSAR, Section 8.3.2.2.1.3 describes that the safety-related divisions of DC complete loss of either of the DC subsystems (one per each DC power necessary to attain safe load group) which supply control power for their respective shutdown for this unit is: Class IE AC load groups will not prevent the minimum safety functions from being performed.

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

a. Alarms:

A-1 (BL001S)

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RESPONSE TO GENERIC I EITER 91-06 UESTION RESPONSE

1. Battery disconnect or Yes On annunciator panels ESA-UA-2E and ESB-UA-2F circuit breaker open? (Procedures 41AI 1ES2A, 41AL-1ES2B, 42AI 2ES2A, 42AI 2ES2B, 43AL-3ES2A, and 43AI 3ES2B).

2. Battery charger No A separate independently annunciated alarm for an open disconnect or circuit charger disconnect or open input circuit breaker is not breaker open (both provided. However, these alarms are provided on the common input AC and output charger trouble alarm for each charger, which provides DC)? annunciation, CRT display, and typewriter printout in the Control Room (Dwg 13-E-PKB-004).

3. DC system ground? No Independent annunciation is not provided, however, DC system ground is alarmed on a common alarm for each DC subsystem, which provides annunciation, CRT display, and typewriter printout in the Control Room (Dwgs 13-E-PKB-001 and 13-E-PKB-002).

4. DC bus undervoltage? No Independent annunciation is not provided, however, DC system undervoltage is alarmed on a common alarm for each DC subsystem, which provides annunciation, CRT display, and typewriter printout in the Control Room (Dwgs 13-E-PKB-001 and 13-E-PKB-002).

5. DC bus overvoltage? No Bus overvoltage is not provided, but overvoltage is alarmed as a part of the common alarm (the charger DC high voltage output relay is monitoring the DC bus potential). The common alarm provides annunciation, CRT display, and typewriter printout in the Control Room (Dwgs 13-E-PKA-002, 13-E-PKA-004, 13-E-PKA-005, 13-E-PKA-007, and 13-E-PKB-004).

A-2 (BLOOIS)

0 RESPONSE TO GENERIC LEITER 91-06 UESTION RESPONSE

6. Battery charger failure? No Independent annunciation is not provided, however, battery charger failure is alarmed on a common alarm for each DC subsystem, which provides annunciation, CRT display, and typewriter printout in the Control Room (Dwgs 13-E-PKB-001 and 13-E-PKB-002).

7. Battery discharge? No However, battery discharge is alarmed indirectly. During normal operation, the 125 VDC load and battery charging current is supplied by the battery charger. Failure of the battery charger to supply those loads is alarmed. Charger output voltage is alarmed (charger undervoltage relay) at 120 volts DC. If the bus voltage drops to 112 volts, the DC bus undervoltage relay will actuate an additional alarm (Procedures 41AL-1RK1A, 42AL-2RK1A, 43AL-3RK1A).

b. Indications:

1. Battery float charge No Battery current indication does not read float charge current (it current? has 0-1500 amp scale). However, the control room has voltage indication that corresponds to charge/discharge. Also, float charge current is verified during the 7-day surveillance (Procedure 32ST-9PK01).

2. Battery circuit output Yes Panel B01 (Dwgs 13-E-PKB-001 and 13-E-PKB-002).

current?

3. Battery discharge? No Battery discharge indicator is not provided; however, a weekly surveillance test is performed to obtain specific gravity and voltage of each designated pilot cell. This indicates the state of battery charge (Procedure 32ST-9PK01).

A-3 (8L001S)

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RESPONSE TO GENERIC LEITER 91-06 UESTION RESPONSE

4. Bus voltage? Yes Panel B01 (Dwgs 13-E-PKA-002, 13-E-PKA-004, 13-E-PKA-005, 13-E-PEA-007).

c. Does the unit have written Yes These procedures are:

procedures for response to the above alarms and Procedures 41AL-1RK1A, 41AI 1ES2A, 41AL-1ES2B indications? 42AL-2RK1A, 42AI 2ES2A, 42AI 2ES2B 43AL-3RK1A, 43AL-3ES2A, 43AL-3ES2B

4. Does this unit have indication of Yes Annunciation is provided when battery breakers are not in the bypassed and inoperable status of closed operating position. Annunciation is provided when the circuit breakers or other devices charger AC power breaker is open or the DC disconnect is that can be used to disconnect the open, as discussed in question 3.a.2 response (Dwgs 13-E-PKB-battery and battery charger from 001, 13-E-PKB-002, 13-E-PKB-004).

its DC bus and the battery charger from its AC power source during maintenance or testing?

5. If the answer to any part of JustiGcation is provided in the Comments/JustiGcation section question 3 or 4 is no, then provide following each specific question with a "no" answer.

information justifying the existing design features of the facility's safety-related DC systems. *See note below.

6. (1) Have you conducted a review No Physical separation, electrical isolation, and redundancy are of maintenance and testing provided to prevent the occurrence of common mode failures.

activities to minimize the potential In addition, no provision exists for transferring loads between for human error causing more redundant 125 V-DC subsystems (UFSAR 8.3.2.2.1.3 and than one DC division to be 8.3.2.2.1.16).

unavailable? and A-4 (BL001S)

k RESPONSE TO GENERIC LETTER 91-06 UESTION RESPONSE (2) Do plant procedures prohibit Yes This is addressed in Procedures 40AC-90P18, and 73AC-9ZZ04.

maintenance or testing on Also, Technical SpeciGcations 3.8.2.1 and 3.8.2.2 require at least redundant DC divisions at the one operable DC train in all modes.

same time?

If the facility Technical SpeciGcations The PVNGS Technical Specifications have provisions equivalent have provisions equivalent to those to those found in the Combustion Engineering Standard found in the Westinghouse and Technical Specifications for maintenance and surveillance; Combustion Engineering Standard however, question 7 will be answered for veriGcation purposes.

Technical Specifications for maintenance and surveillance, then question 7 may be skipped and a statement to that effect may be inserted here:

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 Yes Technical Specification Surveillance Requirement 4.8.2.1; level? Procedure 32ST-9PK01.

2. Specific gravity or Yes Technical Specification Surveillance Requirement 4.8.2.1; charging current? Procedure 32ST-9PK01.

3. Float voltage? Yes Technical Specification Surveillance Requirement 4.8.2.1; Procedure 32ST-9PK01.

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RESPONSE TO GENERIC LEITER 91-06 UESTION RESPONSE

4. Total bus voltage on Yes Technical Specification Surveillance Requirement 4.8.2.1; fioat charge? Procedure 32ST-9PK01.

5. Physical condition of all Yes Procedure 32ST-9PK01.

cells?

b. At least once per 92 days, or Technical Specification 4.8.2.1.b specifies these surveillance within 7 days after a battery requirements be performed at least once per 92 days and within discharge, overcharge, or if 7 days after a battery discharge with a battery terminal voltage the pilot cell readings are below 105 volts, or battery overcharge with a battery terminal outside the 7-day surveillance voltage above 145 volts. Technical specification Table 4.8-2, requirements are the footnote (1) specifies that if any category A parameter following verified to be within (including pilot cell specific gravity or battery charging current acceptable limits: less than two amps on charge) is outside the 7 day surveillance requirement, all category B measurements (including those parameters in Question 7.b, 1 through 6 of this response below) must be taken and found within their allowable values.

1. Electrolyte level of each Yes Technical Specification Surveillance Requirement 4.8.2.1; cell? Procedure 32ST-9PK02.

2. The average specific Yes Technical Specification Surveillance Requirement 4.8.2.1; gravity of all cells? Procedure 32ST-9PK02.

3. The specific gravity of Yes Technical Specification Surveillance Requirement 4.8.2.1; each cell? Procedure 32ST-9PK02.

4. The average electrolyte Yes Technical Specification Surveillance Requirement 4.8.2.1; temperature of a Procedure 32ST-9PK02.

representative number of cells?

A-6 (BL0018)

I' RESPONSE TO GENERIC L5WHER 91-06 UESTION RESPONSE

5. The float voltage of each Technical Specification Surveillance Requirement 4.8.2.1; cell? Procedure 32ST-9PK02.

6. Visually inspect or No Technical Specification Surveillance Requirement 4.8.2.1 and measure resistance of Procedure 32ST-9PK02 require visual inspection or resistance terminals and connectors measurement of battery terminals and connectors during the 92 (including the connectors day surveillance test of station batteries. However, the DC bus at the DC bus)? connector visual inspection is done as part of the inspection and testing of the DC motor control center, scheduled every third refueling outage. Increased periodicity of the DC bus connector visual inspection is not considered necessary because these connectors are not in close proximity to the battery cells, and therefore are not subject to the potentially corrosive environment of the battery.

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

1. Low resistance of each Yes Technical Specification Surveillance Requirement 4.8.2.1; connection (by test)? Procedure 32ST-9PK03.

2. Physical condition of the Yes Technical Specification Surveillance Requirement 4.8.2.1; battery? Procedure 32ST-9PK03.

3. Battery charger Yes Technical Specification Surveillance Requirement 4.8.2.1; capability to deliver Procedure 32ST-9ZZ34.

rated ampere output to the DC bus?

A-7 (BL001S)

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RESPONSE TO GENERIC LEITER 91-06 UESTION RESPONSE

4. The capability of the Yes Technical SpeciGcation Surveillance Requirement 4.8.2.1; battery to deliver its Procedure 32ST-9PK03.

design duty cycle to the DC bus?

5. Each individual cell Yes Procedure 32ST-9PK03 requires that each cell voltage be voltage is within monitored during the 18 month battery service discharge test, so acceptable limits during that the test can be suspended when any cell voltage drops the service test? below acceptable limits.

d. At least every 60 months, is Yes Technical Specification Surveillance Requirement 4.8.2.1.

capacity of each battery veriGed by performance of a discharge test?

e. At least annually, is the Yes Technical SpeciGcation Surveillance Requirement 4.8.2.1.

battery capacity veriGed by performance discharge test, if the battery shows signs of degradation or has reached 85% of the expected service life?

8. Does this plant have operational features such that following loss of one safety-related DC power supply or bus:

A-8 (BU$ 1S)

E RESPONSE TO GENERIC LETTER 91-06 UESTION RESPONSE

a. Capability is maintained for Yes The PVNGS UFSAR, Section 8.3.2.2.1.13 discusses how each ensuring continued and unit has separate and independent DC electric systems capable adequate reactor cooling? of supplying minimum ESF loads and loads required for attaining a safe and orderly cold shutdown of the unit assuming a single failure. Procedures 41AO-1ZZ17, 42AO-2ZZ17 and 43AO-3ZZ17 provide guidance to the operators for actions following loss of 125 VDC Class IE electrical power and address the capability to ensure that continued and adequate core cooling is maintained.

b. Reactor coolant system Yes The PVNGS UFSAR, Section 8.3.2.2.1.13 discusses how each integrity and isolation unit has separate and independent DC electric systems capable capability are maintained? of supplying minimum ESF loads and loads required for attaining a safe and orderly cold shutdown of the unit assuming a single failure. Procedures 41AO-1ZZ17, 42AO-2ZZ17 and 43AO-3ZZ17 provide guidance to the operators for actions following loss of 125 VDC Class IE electrical power and address maintaining reactor coolant system integrity and isolation capability.

c. Operating procedures, Yes Procedures 41AO-1ZZ17, 42AO-2ZZ17, 43AO-3ZZ17, provide instrumentation (including guidance to the operators for actions following loss of 125 VDC indicators and annunciators), Class IE electrical power. These procedures describe the and control functions are indicators and annunciators and control functions to initiate adequate to initiate systems systems as required to maintain adequate core cooling.

as required to maintain adequate core cooling?

A-9 (BM01S)

RESPONSE TO GENERIC LEITER 91-06 UESTION RESPONSE

9. If the answer to any part of The basis for the "no" answers to questions 6(1) and 7.b.6 are question 6, 7 or 8 is no, then provided in the Response section for those questions. All other provide your basis for not parts to question 6, 7 and 8 are answered "yes".

performing the maintenance, surveillance and test procedures described and/or the bases for not including the operational features cited. "See note below.

• Note: For questions involving The supporting information and justiGcation for any "no" supporting type information (question responses has been provided in this submittal. No further numbers 5 and 9), instead of developing evaluation of the need for the provisions with "no" responses is and supplying the information in planned.

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 vulnerabilities (IPE). If you select this option, you are required to:

So state in response to these questions, and (2) Commit to explicitly address questions 5 and 9 in your IPE submittal per the guidelines outlined in NUREG-1335 (Section 2.1.6, Subitem 7), "Individual Plant Examination: Submittal Guidance."

A-10 (BL001S)

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