ML17305A489

Forwards Technical Justification to Assure NRC That Facility Design Has Included Features Required by Generic Ltr 89-19

ML17305A489
Person / Time
Site:	Palo Verde
Issue date:	01/22/1990
From:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
161-02793-WFC-S, 161-2793-WFC-S, GL-89-19, NUDOCS 9002050211
Download: ML17305A489 (14)

Text

ACCELERATED STRIBUTION DEMONS TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9002050211 DOC.DATE: 90/01/22 NOTARIZED: YES DOCKET 41T 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 RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards technical justification for safety implication of control sys,per 890920 Generic Ltr.

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: General Distribution 05000528 NOTES'tandardized plant. 05000529 Standardized plant. 05000530 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 CHAN,T 5 5 DAVIS,M. 5 5 PETERSON,S. 5 5 INTERNAL: ACRS 6 6 NRR/DET/ECMB 9H 1 1 NRR/DOEA/OTSB11 1 1 NRR/DST 8E2 1 1 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 NRR/DST/SRXB 8E 1 1 NUDOCS-ABSTRACT 1 1 OC/ 1 0 OGC/HDS1 1 0 01 1 1 RES/DSIR/EIB 1 1 EXTERNAL: LPDR 1 1 NRC PDR 1 1 NSIC 1 1 NOTES 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTEr CONTACT THE DOCUMENT CONTROL DESK ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISI'RIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 38 ENCL 36

ii II Arizona Public Service Company P.O. BOX 53999 ~ PHOENIX. ARIZONA 850724999 WILLIAMF. CONWAY EXECUTIVEVICE PRESIDENT NUCLEAR 161-02793-WFC/SKW January 22, 1990 Docket Nos. STN 50-528/529/530 Document Control Desk U. S. Nuclear Regulatory Commission Mail Station Pl-37 Washington, D. C. 20555

Reference:

NRC Letter to all Licensees Holding Licenses and Construction Permits for Nuclear Power Reactor Facilities," Safety Implication of Control Systems in LWR Nuclear Power Plants," Generic Letter 89-19 dated September 20, 1989

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3 Technical Justification for Safety Implication of Control Systems File: 89-052-026 Arizona Public Service is submitting a technical justification to assure the NRC that the PVNGS design has included the features required by Generic Letter 89-

19. The attached technical justification includes the details of the design.

If you have any questions regarding this submittal, please contact A. Carter Rogers of my staff at (602) 340-4041.

Sincerely, WFC/SKW/j le cc: G. W. Knighton T. L. Chan M. J. Davis J. B. Martin T. J. Polich A. H. Gutterman 00 90020502 ADOCK i1 gaol ZK 0500052S PDR P PDC

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STATE OF ARIZONA )

) ss.

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 2A Dsy Of 1990.

Notary Public e

My Commission Expires 4 CNMBsian Expires June 5, Q

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Document Control Desk 161-02793-WFC/SKW U. S. Nuclear Regulatory Commission January 22, 1990 Page 2 bcc: J. N. Bailey (1966)

J. M. Levine (6125)

J. E. Allen (1875)

T. H. Cogburn (6102)

W. F. Quinn (1502)

E. C. Sterling (1878)

G. W. Sowers (6081)

J. S. Summy (6076)

J. H. Hesser (1855)

R. A. Bernier (1515)

G. Sen (1515)

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JUSTIFICATION FOR ADE UACY OF DESIGN The NRC staff, in Generic Letter 89-19, concluded that all PWR plants should provide automatic steam generator overfill,protection. In addition, plant procedures and technical specifications for all plants should include provisions to. verify periodically the operability of the overfill protection and to assure that the automatic overfill protection is available to mitigate main feedwater overfill events during reactor power operation. Also the system design and setpoints should be selected with the objective of minimizing inadvertent trips of the main feedwater system during plant startup, normal operation and protection system surveillance.

Palo Verde Nuclear Generating Station (PVNGS) has a safety grade automatic reactor trip and Main Steam Isolation Signal (MSIS), on high steam generator level. On an MSIS both the Main .Steam Isolation Valves and the Feedwater Isolation Valves close.

The reactor trip and MSIS on high steam generator level provide the overfill protection requested by Generic Letter '89-19. The high steam generator level has a setpoint of 91% of narrow range of steam generator level to initiate both a reactor trip and a MSIS actuation. The trip and actuation operate on a two-out-of-four initiating logic. The MSIS isolates the main feedwater -from the steam generator by closing Feedwater Isolation Valves when steam generator level increases to the setpoint. The Generic Letter requests a main feedwater pump trip on high steam generator level. The PVNGS design has achieved the same results as tripping the main feedwater pump by isolating the main feedwater to the steam generator on high'evel.

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JUSTIFICATION FOR ADE UACY OF DESIGN This design is- part of the Plant Protection System which is required by 10 CFR 50 to be separate from the control systems. A loss o'f power, loss of ventilation, or a fire in the Feedwater Control System (FWCS), would not,effect the operation of the high steam generator level trip or the MSIS actuation. The Plant Protection System is powered by class .power and is electrically isolated and physically separated from the FWCS..

The overfill protection is surve'illed under Technical Specifications 4.3.1.1, 4.3.1.2, 4.3.1.3, 4.3.2.1, 4.3.2.2, and 4,.3.2.3. It is covered under Limiting Conditions for Operation 3.3.1 and 3.3.2 and Limiting Safety System Settings 2 '.1.

In addition, the FWCS has a high level override feature which should prevent the need for the use of the safety system. At a high steam generator level setpoint (86% Narrow Range), the FWCS decreases the pump speed and closes the economizer and the downcomer valves to prevent an overfill of the steam generators. While this feature of PVNGS design is not safety-related, it does provide a first barrier to prevent an overfill event.

Furthermore, PVNGS is, designed with a:high-pressure-injection t pump-discharge pressure greater than '1275 psi., Therefore, reassessment of emergency procedures and operator training programs to ensure.operator's capability to'handle the full spectrum of possible small-'break loss,-of-coolant (SBLOCA) scenarios is not required in accordance with Generic Letter 89-19 Enclosure 2 .Items '4 'C.

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JUSTIFICATION FOR ADE UACY OF DESIGN Since PVNGS has a safety-related design which incorporates the features the NRC requested in Generic Letter '89-19,, no further design changes .are required.

t In addition, the control grade FWCS high level override feature should normally prevent the need for use of the safety grade system. Also, PVNGS has not experienced a false reactor trip or MSIS on high steam generator level during plant operations.

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