ML17306A622
| ML17306A622 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/29/1992 |
| From: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 161-04701-WFC-R, 161-4701-WFC-R, NUDOCS 9204060130 | |
| Download: ML17306A622 (5) | |
Text
~ACCELERATED DISTRIBUTION DEMONSTPMTION SYSTEM REGULAT 5 INFORMATION DISTRIBUTIO YSTEM (RIDS)
ACCESSION NBR:9204060130 DOC.DATE: 92/03/29 NOTARIZED:
NO DOCKET g
FACIL:O'TN-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:
Submits status of actions to eliminate possibility of multiple control element assembly drop events,per util 891025 ltr transmitting justification for continued operation. Revised design change installed in Jan 1992.
DISTRIBUTION CODE:
A001D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal: General Distribution D
NOTES:STANDARDIZED PLANT Standardized plant.
Standardized plant.
RECIPIENT ID CODE/NAME PD5 LA TRAMMELLgC INTERNAL: ACRS NRR/DET/ESGB NRR/DST 8E2 NRR/DST/SICB8H7 NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB EXTERNAL: NRC PDR NOTES:
COPIES LTTR ENCL RECIPIENT ID CODE/NAME PD5 PD THOMPSON,M NRR/DET/ECMB 7D NRR/DOEA/OTSB11 NRR/DST/SELB 7E NRR/DST/SRXB 8E OC/LFM EG$PTB Ol NSIC COPIES LTTR ENCL 05000528 A
05000529 05000530 D
D NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE'ONTACTTHE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
D D
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 27 ENCL
Arizona Public Service Company P.O. POX 53999
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PHOENIX, ARIZONA85072-3999 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555 161-04701-WFC/RAB March 29, 1992
References:
1)
Letter 161-02523-WFC/RAB/JST, dated October 25, 1989, from W. F. Conway, APS, to NRC, "Justification for Continued Operation as a Result of CEA Drop Events, Revision 3" 2)
Letter 161-03242-WFC/JST, dated May 23, 1990, from W. F. Conway, APS, to NRC, "Status of Improvements to Eliminate the Possibility of Multiple CEA Drop Events" 3)
Letter 161-03364-WFC/JST, dated July 25, 1990, from W. F. Conway, APS, to NRC, "Status of Justification for Continued Operation-Control Element Assembly (CEA) Drop Events, Revision 3"
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, and 3 Docket Nos. STN 50-528/529/530 Status of Actions to Eliminate the Possibility of Multiple Control Element Assembly Drop Events File: 92-056-026 92-177-419 Arizona Public Service Company (APS) forwarded to the NRC in Reference 1, Revision 3 to the Justification for Continued Operation (JCO), and provided a corrective action plan to prevent grounding of Control Element Drive Mechanism (CEDM) lower lift coil leads.
Reference 2 provided the status of implementation and additional details of the improvement being made to minimize the possibility of multiple Control Element Assembly (CEA) drop events.
Reference 3 informed the NRC that the Plant Review Board (PRB) had approved suspension of the JCO for Units 1 and 2 on June 8, 1990, after the corrective actions had been implemented.
Reference 3 also described a design change to reverse CEDM lower latch coil polarity, and provided a schedule for implementation.
Reversal of the latch coil polarity will enhance long-term coil life, but it is not necessary to meet the requirements of the JCO.
'II204060130< 920329 PDR ADOCK=05000528 P
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161-04701-WFC/RAB March 29, 1992 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk CEA Drop Events Page 2 On June 5, 1991, the PRB approved suspension of the JCO for Unit 3, upon completion of the corrective actions to satisfy the requirements of the JCO.
The polarity reversal modification was completed in Unit 3 during the refueling outage which was completed in June 1991."
Duririg low-power physics testing, CEA position indication anomalies were noted when CEAs were moved.
Coil polarity was restored to its original configuration, which eliminated the position indication anomalies, and the unit was restarted.
Testing by Combustion Engineering determined that the reversed polarity configuration resulted in sufficient magnetic flux at the center of the reactor vessel head to interact with the reed switch position transmitter and to cause the anomaly.
The magnetic flux interaction only occurs at the center of the reactor vessel head, and only when the four CEDMs surrounding the center CEA position transmitter are energized simultaneously.
This anomaly had not been predicted during preparation of the design change.
As a result of the testing, the design change was modified. The revised design change was installed and satisfactorily tested in Unit 2 during the refueling outage which was completed in January 1992. This change is being made to the Unit 1 CEDMs during the current refueling outage, and willbe completed in Unit 3 during its next refueling outage, currently scheduled for Fall 1992.
If you have any questions, please call Michael E. Powell of my staff at (602) 340-4981.
Sincerely, WFC/RAB/pmm cc:
J. B. Martin D. H. Coe A. H. Gutterman A. C. Gehr