ML17310B434

Application for Amends to Licenses NPF-41,NPF-51 & NPF-74, Increasing Min Nitrogen Accumulator Pressure

ML17310B434
Person / Time
Site:	Palo Verde
Issue date:	06/17/1994
From:	Stewart W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17310B435	List: ML17310B434
References
102-03009-WLS, 102-3009-WLS, NUDOCS 9407200235
Download: ML17310B434 (13)

Text

P R.IC3R.IWY' (ACCELERATED RIDS PROCESSING REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9407200235 DOC.DATE: 94/06/17 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 P AUTH. NAME AUTHOR AFFILIATION STEWART,W.L. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document. Control Branch (Document Control Desk)

SUBJECT:

Application for amends to licenses NPF-41,NPF-51 & NPF-74, increasing min nitrogen accumulator pressure.

0 DISTRIBUTION CODE: ZOOID TITLE: OR COPIES RECEIVED:LTR Submittal: General Distribution 2 ENCL / SIZE:

R NOTES:STANDARDIZED PLANT 05000528 Standardized plant. 05000529 I Standardized plant. 05000530 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PDIV-3 LA 1 1 PDIV-3 PD 1 1 HOLIAN, B 2 2 TRAN,L 2 2 INTERNAL: ACRS 6 6 NRR/DE/EELB 1 1 NRR/DORS/ONDD 1 1 NRR/DRCH/HICB 1 1 NRR/DRPW 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NUDOCS-ABSTRACT 1 "1 OC/~LDCB 1 0 OGC/HDS2 1 0 D G 01 1 1 EXTERNAL: NRC PDR 1 1 NSIC 1- ' 0 C

U NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE I-IELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P! -37 (EXT. 504-2083 ) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS I'OR DOCUMENTS YOU DON"I'EED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 24 ENCL 22

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Arizona'Public Service Company P.O. BOX 53999 ~ PHOENIX. ARIZONA85072<999 102-03009-WLS/RAB/ZJE WILLIAML. STEWART June 17, 1994 EXECUTIVEVICEPRESIDENT NUCLEAR U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555

Subject:

'aloUnits Verde Nuclear Generating Station and 3 (PVNGS) 1, 2, Docket Nos. STN 50-528/529/530 Proposed Amendment to Technical Specification Section 3/4.7.1.6 and Bases for 3/4.7.1.6 File: 94-056-026'4-005-41 9.05 Arizona Public Service Company is requesting an amendment to the Surveillance Requirements of Technical Specification (TS) Section 3/4.7.1.6 and the Bases of Section 3/4.7.1.6. The request increases the minimum nitrogen accumulator pressure. The change.to the Bases increases the minimum time the Atmospheric Dump Valve accumulators must be operable.

Provided in the enclosure to this letter are the following sections which support the proposed Technical Specification amendment:

A. Description of the Proposed Amendment Request B. Purpose of the Technical Specification C. Need for the Technical Specification Amendment, D. Safety Analysis of the Proposed Technical Specification Amendment E. No Significant Hazards Consideration Determination F. Environmental Impact Consideration Determination G. Marked-Up Technical Specification Change Pages Pursuant to 10 CFR 50.91(b)(1), a copy of this request is being forwarded to the Arizona Radiation Regulatory Agency.

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U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Proposed Technical Specification Amendment to Section 3/4.7.1.6 Page 2 In accordance with Technical Specification 6.5, the Plant Review Board and the Offsite Safety Review Committee have reviewed and concurred with this request.

Should you have any questions, please contact Richard A. Bernier of my staff at (602) 393-5882.

Sincerely, WLS/RAB/ZJE/did Enclosure cc: L. J. Callan B. E. Holian K. E. Johnston K. E. Perkins A. V. Godwin (ARRA)

,li STATE OF ARIZONA )

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COUNTY OF MARICOPA )

I, W. L. Stewart, 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. L. St wart a

Sworn to Before Me This /7 Day of , 1994.

c Notary Public My Commission<xpire SEAL OPFIC1AL RAh1ONA WRIGHT Notary Public- State of Arizona MARlCOPA COUNTY My QanNot fgllfahe f5.NT

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ENCLOSURE INCREASE IN MINIMUMNITROGEN ACCUMULATOR PRESSURE FOR THE ATMOSPHERIC DUMP VALVES (ADVs)

ENCLOSURE A. DESCRIPTION OF THE PROPOSED AMENDMENT REQUEST Technical Specification 3/4.7.1.6 minimum nitrogen accumulator pressure is raised from

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400 psig to 615 psig due to a change in the Design Basis for the accumulator.

B. PURPOSE OF THE TECHNICAL SPECIFICATION Technical Specification 3/4.7.1.6 ensures that a minimum number of Atmospheric Dump Valves (ADVs) are available for plant cooldown. The Updated Final Safety Analysis Report (UFSAR) does not credit the ADVs for mitigating the consequences of an accident in the Chapter 15 accident analyses; however, the ADVs are credited for use in cooling down a Unit in the event of a loss-of-offsite power. loss-of-offsite power would cause a loss of the main condenser as a heat sink. The ADVs in conjunction with the Auxiliary Feedwater System would provide that heat removal function for long-term heat removal and cooldown.

The limitation on minimum nitrogen accumulator pressure is to ensure maintenance of a sufficient volume of nitrogen in the accumulator to operate its associated ADV. A sufficient nitrogen volume is required to operate the ADV in HOT STANDBY plus to allow the unit to reach COLD SHUTDOWN under natural circulation conditions in the event of a failure of the normal control air system.

C. NEED FOR THE TECHNICAL SPECIFICATION AMENDMENT Arizona Public Service Company (APS) has reanalyzed the Design Basis for nitrogen accumulator sizing. The limiting event is ADV availability to reach COLD SHUTDOWN under natural circulation conditions in the event of failure of the normal control air system.

APS substituted operating plant data for the assumptions used by Combustion Engineering in a computer simulation of the cooldown. The data was obtained during Unit 1 post-fuel load Natural Circulation testing. The result of the reanalysis is that the ADVs are required to operate for 13.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> versus the previously calculated 10.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

A minimum of 615 psig accumulator pressure is required to ensure ADV availability during a Natural Circulation Cooldown.

D. SAFETY ANALYSISOF THE PROPOSED TECHNICALSPECIFICATION AMENDMENT The UFSAR assumes operation of the ADVs for long term heat removal and cooldown (UFSAR Section 6.3.3.4). The ADVs are not credited in Chapter 15 events until 30 minutes after the initiating event. One ADV per steam generator is assumed available for the duration of the long-term cooling event.

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The limitation on maintaining the nitrogen accumulator at a pressure > 615 psig is to ensure that a sufficient volume of nitrogen is in the accumulator to operate the associated ADV. A pressure of 615 psig ensures that there is sufficient nitrogen for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of operation at HOT STANDBY plus 9.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of operation to reach COLD SHUTDOWN under natural circulation conditions in the event of failure of the normal control air system.;

The new minimum pressure is based on operating experience rather than theoretical assumptions. Overall there is an increase in safety.

E. NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION The Commission has provided standards for determining whether a no significant hazards consideration exists as stated in 10 CFR 50.92. A proposed amendment to an operating license for a facility involves a no significant hazards consideration if operation of the

facility in accordance with a proposed amendment would not: (1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2)

Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety.

A discussion of these standards as they relate to the-amendment request follows:

Standard 1 Involve a significant increase in the probability or consequences of an accident previously evaluated.

The proposed Technical Specification change in the nitrogen accumulator supply minimum pressure will not increase the probability or consequences of any accident previously analyzed. The nitrogen accumulator pressure is normally maintained between 650-680 psig. Nitrogen pressure from the accumulator is reduced to 105 psig prior to use in the operation of the ADVs. The pressure reduction will remain the same with the higher minimum accumulator pressure.

Standard 2 Create the possibility of a new or different kind, of accident from any accident previously evaluated.

Increasing the nitrogen accumulator minimum pressure does not create any new or different accidents than those previously evaluated. The normal air supply (the Instrument Air System) to the ADV is maintained between 105 to 125 psig. Currently, nitrogen from the accumulator is reduced to 105 psig prior to use in the ADV. The increased minimum pressure in the accumulator will still be reduced to 105 psig prior to use in the ADV.

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Standard 3 Involve a significant reduction in a margin of safety.

The limitation on maintaining the nitrogen accumulator at a certain pressure is to ensure that a sufficient volume of nitrogen is in the accumulator to operate the associated ADV.

Maintaining a higher minimum pressure ensures that sufficient nitrogen will be available to maintain the unit at HOT STANDBY for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and an additional 9.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> to reach COLD SHUTDOWN under natural circulation conditions in the event of failure of the normal control air system. Therefore, the proposed change does not involve a reduction in a margin of safety.

F. ENVIRONMENTALIMPACT CONSIDERATION DETERMINATION The proposed amendment changes the SURVEILLANCE requirements for the ADV.

APS has determined that the proposed amendments involve no change in the amount or type of any effluent that may be released offsite, and that there is no increase in individual or cumulative occupational radiation exposure. As such, operation of PVNGS Units 1, 2, and 3 in accordance with the proposed amendment does not involve an environmental impact.

G. MARKED-UP TECHNICAL SPECIFICATION CHANGE PAGES PVNGS Unit 1 PVNGS Unit 2 PVNGS Unit 3 3/4 7-10 3/4 7-10 3/4 7-10 B 3/4 7-3 B 3/4 7-3 B 3/4 7-3 3of3

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