ML17311A600
| ML17311A600 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/27/1995 |
| From: | Stewart W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 102-03235-WLS-S, 102-3235-WLS-S, NUDOCS 9502060328 | |
| Download: ML17311A600 (13) | |
Text
PR.IC)H.I EY' (ACCELERATED RIDS P ROC I'.SSli6 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9502060328 DOC.DATE: 95/01/27" NOTARIZED: NO DOCKET FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 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)
P
SUBJECT:
Forwards addi info requested during 950112 telcon w/L Tran of NRC re proposed amend to TS Section 3/4.4.2,changing pressurizer code safety valve liftsetting from 2,500 psia to 2,475 psia.
DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal:
General. Distribution NOTES:Standardized plant.
R 05000529 I
RECIPIENT ID CODE/NAME PD4-2 LA HOLIAN, B INTERNAL: ACRS NRR/DRCH/HICB NRR/DSSA/SRXB OGC/HDS2 COPIES RECIPIENT LTTR ENCL ID CODE/NAME 1
1 PD4-2 PD 1
1 TRAN,L 6
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~ILE CENTER~01 1
1 NRR/DSSA/SPLB 1
1 NUDOCS-ABSTRACT 1
0 COPIES LTTR ENCL 1
1 1
1 1
1 1
1 1
1 EXTERNAL'OAC 1
1 NRC PDR 1
1 D
N YOTE TO ALL"RIDS" RECIPIEYTS:
PLEASE HELP US TO RFDUCE iVKSTE!COYTACT'I'HEDOCL'XIEYTCONTROL DESK, ROOhf P I -37 (EXT. 504-~083 ) TO EL Iill4'ATE YOL"R i'AifL F RO~f DISTRIBUTIOY,LIS'I'S I'OR DOC!.'h,fEY,'I'S YOI.'OY."I'lI'.D!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 18 ENCL 17
Arizona Public Service Company P.O. BOX 53999
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PHOENIX, ARIZONA85072-3999 WILLIAML. STEWART EXECVTIVEVICE PRESIDENT NUCLEAR 102-03235-WLS/SAB/RKR January 27, 1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555
Reference:
1)
Letter No.
102-03197, dated November 30,
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 2 Docket No. STN 60-529 Request for Additional Information for Proposed Amendment to Technical Specification Section 3/4.4.2 File: 95-066-026 During a January 12, 1995 telecon, Linh Tran of your staff requested additional information to complete the review of the amendment to Technical Specification 3/4.4.2 (Reference 1). The proposed amendment willchange the pressurizer code safety valve lift setting from 2500 psia to 2475 psia to permit Unit 2 to operate with up to 1500 plugged tubes in each steam generator.
The enclosure to this letter provides the requested information.
Should you have any questions, please contact Scott A.
Bauer of my staff at (602) 393-5978.
Sincerely, WLS/SAB/RKR/rv Enclosure cc:
L. J. Callan K. E. Perkins B. E. Holian K. E. Johnston A. V. Godwin ARRA 9502060328 950127 PDR ADOCK 05000529 P
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ENCLOSURE RESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONfOR PROPOSED AMENDMENTTO TECHNICALSPECIFICATION SECTION 3/4.4.2
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~NRS R Provide a discussion of the Chapter 15 events reviewed to determine that the Loss of Condenser Vacuum (LOCV) and Feedwater Line Break are the primary pressure peaking events.
A~PS R The Updated Final Safety Analysis Report (UFSAR) was reviewed to determine the Chapter 15 Design Basis Events (DBEs) that could be adversely affected by the proposed TS change.
The following is a listing of the pressure peaking events for each accident category:
INCREASE IN HEAT REMOVAL BY THE SECONDARY SYSTEM (UFSAR Section 15.1)
UFSAR Section 15.1.4 identifies the Inadvertent Opening of a Steam Generator Relief or Safety Valve (IOSGADV) with Loss of Offsite'Power (LOP) after Turbine Trip as the most limiting pressure peaking event in this accident category.
The peak Reactor Coolant System (RCS) pressure for.this event does not reach the proposed pressurizer safety valve setpoint; therefore, this setpoint change does not affect this event.
DECREASE IN HEAT REMOVAL BY THE SECONDARY SYSTEM (UFSAR Section 15R2)
Moderate Fre uenc and Infre uent Events UFSAR Section 15.2.3 identifies the LOCV event as the most limiting pressure'eaking event of the moderate frequency and infrequent events in this category, with 2742 psia peak RCS pressure.
The reanalysis determined that the peak RCS pressure, assuming 1500 plugged tubes and a pressurizer code safety valve nominal lift setpoint of 2475 psia, is 2728 psia.
Therefore, the proposed lower point set valves (PSV) setpoint provides additional margin to the 2750 psia acceptance criteria (110% of design pressure).
Limitin Fault Events UFSAR Section 15.2.8 identifies the large feedwater line break (FLB) with a loss of alternating current (LOAC) as the most limiting pressure peaking event of the limiting fault events in this category with 2843 psia peak RCS pressure.
The reanalysis determined that the peak RCS pressure, assuming 1500 plugged tubes and a pressurizer code safety valve nominal lift setpoint of 2475 psia, is 2813 1 of4
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psia.
Therefore, the proposed lower PSV setpoint provides additional margin to the 3000 psia acceptance criteria (120% of design pressure).
DECREASE IN REACTOR COOLANT FLOWRATE (UFSAR Section 15.3)
Moderate Fre uenc and lnfre uent Events UFSAR Section 15.3.1 identifies the Total Loss of Reactor Coolant Flow as the most limiting pressure peaking event of the moderate frequency and infrequent events in this category, with 2576 psia peak RCS pressure.
The proposed lower PSV setpoint provides additional margin to the 2750 psia acceptance criteria (110% of design pressure).
Limitin Fault Events UFSAR Section 15.3.3 identifies the Single Reactor Coolant Pump Rotor Seizure with LOP as the most limiting pressure peaking event of the limiting fault events in this category, with 2387 psia peak RCS pressure.
This peak pressure is less than the proposed setpoint; therefore, the proposed change does not affect this'vent.
REACTIVITYANDPOWER DISTRIBUTIONANOMALIES(UfSAR Section 15.4)
Moderate Fre uenc and Infre uent Events UFSAR Section 15.4.2 identifies the Uncontrolled Control Element Assembly (CEA) Withdrawal at Power as the most limiting pressure peaking event of the moderate frequency and infrequent events in this category, with 2370 psia peak RCS pressure.
This peak pressure is less than the proposed setpoint; therefore, the proposed change does not affect this event.
Limitin Fault Events UFSAR Section 15.4.8 identifies the CEA ejection event as the most limiting pressure peaking event ofthe limiting fault events in this category, with 2757 psia peak RCS pressure.
The proposed lower PSV setpoint provides additional margin to the 3000 psia acceptance criteria (120% of design pressure).
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'INCREASE IN REACTOR COOLANT SYSTEM INVENTORY (UFSAR Section 16.6)
Moderate Fre uenc Events UFSAR Section 15.5.1 identifies the Inadvertent Operation of the ECCS as the most limiting pressure peaking event of the moderate frequency events in this category, with peak RCS pressure less than the HPSI shutoff head pressure of 1715 psia.
This peak pressure is less than the proposed setpoint; therefore, the proposed change does not affect this event.
Infre uent Events UFSAR Section 15.5.2 identifies the chemical and volume control system (CVCS)
Malfunction-Pressurizer Level Control System Malfunction with LOP as the most limiting pressure peaking event of the infrequent events in this category, with 2561 psia peak RCS pressure.
The proposed lower PSV setpoint provides additional margin to the 2750 psia acceptance criteria.(110% of design pressure).
DECREASE IN REACTOR.COOLANT SYSTEM INVENTORY(UFSAR Section 16.6)
Moderate Fre uenc Events UFSAR Section 15.6.2 identifies the Double-Ended Break of a Letdown Line Outside Containment as the most limiting pressure peaking event ofthe moderate frequency events in this category, with RCS pressure decreasing during this event; therefore, this setpoint change does not affect this event.
Infre uent Events UFSAR Section 15.6.3 identifies the Steam Generator Tube Rupture as the most limiting pressure peaking event of the infrequent events in this category.
RCS pressure decreases during this event; therefore, this setpoint change does not affect this event.
SUMMARY
Based on this review of these DBEs, the LOCV (UFSAR Section 15.2.3) and FLB (UFSAR Section 15.2.8) events were identified as requiring a detailed evaluation (the remaining Chapter 15 DBEs were either not affected by this change or are less limiting than these events).
The LOCVand FLB are the most limiting primary pressure peaking events.
The results of the analysis for these events were provided in Reference 1.
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'~MRC ~
Discuss why UFSAR Chapter 6 events are not affected by this change.
A~PS ~
For UFSAR Chapter 6 events, LOCA and Main Steam Line Break (MSLB), there is a loss of primary system pressure; therefore, the PSVs are not challenged by these events.
3.
~NRC R Are there any events, other than the pressure peaking events that are affected by the PSV setpoint change?
A~PS ~
No other events are significantly affected by the PSV setpoint change.
The PSVs function to mitigate reactor coolant system pressure transients and maintain the maximum system pressure below the ASME limits. Only those events in which RCS pressure exceeds the PSV setpoint are affected by the change in setpoint.
The'setpoint is determined using the highest value at which acceptable RCS pressures can be obtained during pressure peaking events.
This. minimizes the possibility of inadvertent actuation of the PSVs when they are not required for mitigation of an event.
Lowering the setpoint has a beneficial effect on peak pressure transients by opening the PSVs earlier in the event and reducing the maximum system pressure.
The lower bound of the setpoint (-1%) is set to ensure that, ifrequired, a high pressurizer pressure reactor trip (setpoint of 2383 psia) will occur prior to opening of the PSVs.
Both of these conditions are satisfied with the proposed setpoint change.
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