ML17312A921
| ML17312A921 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/06/1996 |
| From: | Stewart W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17312A922 | List: |
| References | |
| RTR-REGGD-01.121, RTR-REGGD-1.121 102-03748-WLS-A, 102-3748-WLS-A, NUDOCS 9608220237 | |
| Download: ML17312A921 (6) | |
Text
CATEGORY 1 REGULAT.
INFORMATION DISTRIBUTIO YSTEM (RIDS)
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ACCESSION NBR:9608220237 DOC.DATE: 96/OP/06 NOTARIZED: NO DOCKET FACIL:STN-50-530 Palo Vex4e Nuclepr Station, Uni't.3,i,- Arizona Publi 05000530 AU0H.NAME AUTHOR AFFILIATION STEWART,W.L.
Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) l
SUBJECT:
Transmits APS SG Evaluation Rept for PVNGS Unit 3,cyle 6, describing APS's efforts to address presence of Outside C
Diameter Stress Corrosion Cracking in Unit 3 SGs.
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05000530 E RECIPIENT ID CODE/NAME PD4-2 LA CLIFFORD,J.
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Arizona Public Service PALO VERDE NUCLEARGENERATING STATION P.O. BOX 52034 PHOENIX. ARIZONA 85072-2034 WILLIAML STEWART EXECUTIVEVICE PRESICENT NUCLEAR U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001 102-03748-WLS/AKK/JRP August 6, 1996 t
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Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 3 Docket No. STN 50-530 Steam Generator Evaluation Report tt This letter transmits the Arizona Public Service Company (APS) Steam Generator Evaluation Report for the Palo Verde Nuclear Generating Station Unit 3,'cycle 6.
The purpose of this report is to describe the efforts conducted by APS to address the presence of Outside Diameter Stress Corrosion Cracking (ODSCC) in the Unit,3 Steam Generators.
Other degradation mechanisms found in Unit 3, such as tube support and ldose part fretting wear, circumferential cracking at the tube sheet transition, and seconda'ry side corrosion outside the ARC region were not specifically addressed in the assessment.
Based on the results of comprehensive Eddy Current Testing (ECT) examinations, these mechanisms exhibit slow growth and are, therefore, bounded by this evalua )on and past analyses performed by APS.
From an analytical perspective, cycle 6 operation is justified in Unit 3, based on the end of cycle 5 steam generator results.
The assessment contained in this report, is structured to support the continued operation of Unit 3 for at least 15~ months, followirlg.U3R5 (until the next scheduled refueling outage).
The U3R6 refueling outage is currently scheduled for mid March 1997.
The safety significance associated with the operation of Unit 3, until the scheduled U3R6 refueling outage, has been evaluated by APS.
The results of the comprehensive inspection program conducted in U3R5 have been assessed statistically to determine tpe impact of leaving undetected ARC region defects through the remainder of U3C6 operation.
The results of the analyses indicate with high confidence that the conservatle safety margins established in Regulatory Guide 1.121, "Bases for Plugging Degraded PWR Steam Generator Tubes," are maintained. In assessing the safety significance ~of the I
9608220237 960806 PDR ADOCK 05000530 P
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U.S. Nuclear Regulatory Commission ATTN:Document Control Desk Steam Generator Evaluation Report Page 2 current conditions in the Unit 3 steam generators, APS has used, as guidance, the standards as defined in 10 CFR 50.92 for determining whether a significant hazards consideration exists.
The Code states in part that a significant hazard is not involved if the condition would not:
1)
Involve a significant increase in the probability or consequences of an accident previously evaluated; or 2) Create the possibility of a accident from any accident previously evaluated; or 3) Involve a significant reduction in the margin of safety. A discussion of these standards, as they relate to Unit 3 operation until U3R6, is presented in the Safety Assessment of the enclosure (Section C).
APS has reviewed the consequences of previously analyzed accidents with respect to operation with existing steam generator tubing conditions.
To further minimize the consequences on currently analyzed accidents, APS has taken measures to provide operations personnel with diagnostic tools and training. These measures include: event specific training of operations personnel fortube rupture events; improvements in leakage diagnostics via equipment upgrades including the implementation of N-16 monitors; and protocol upgrades to the Emergency Operating Procedures.
These actions permit faster identification and isolation of the affected steam generator should a SGTR event occur.
APS would be pleased to meet with the Staff at your convenience should there be any concerns.
Should you have any questions, please contact Scott A. Bauer at (602) 393-5978.
Sincerely, WLS/SAB/JRP/AI Enclosure CC:
L. J. Callan K. E. Perkins J. W. Clifford K. E. Johnston I.
Barnes