ML17305A977
| ML17305A977 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/25/1990 |
| From: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9008070065 | |
| Download: ML17305A977 (8) | |
Text
ACCELERATED D STRIBUTION DEMONSTPA,TION SYSTEM t
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NOTES:STANDARDIZED PLANT Standardized plant.
Standardized plant.
ACCESSION NBR:9008070065 DOC.DATE: 90/07/25 NOTARIZED: NO FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 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 status of corrective actions to min multiple control element assembly drop events at plant.
DISTRIBUTION CODE:
ADOID COPIES RECEIVED:LTR g ENCL Q SIZE:
TITLE: OR Submittal:
General Distribution REG FILE EXTERNAL: LPDR NSIC NOTES 01 RECIPIENT ID CODE/NAME PD5 LA
'PETERSON,S.
INTERNAL: ACRS NRR/DOEA/OTSB11 NRR/DST/SELB 8D NRR/DST/SRXB 8E COPIES LTTR ENCL 1
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1 1
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1 RECIPIENT ID CODE/NAME PD5 PD TRAMMELL,C.
NRR/DET/ECMB 9H NRR/DST 8E2 NRR/DST/SICB 7E NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB NRC PDR COPIES LTTR ENCL 1
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D NOTE TO ALL"RIDS" RECIPIENTS:
A D
D PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 33 ENCL 31
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WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR Arizona Public Service Company P.O. BOX 53999
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PHOENIX, ARIZONA850724999 161-03364-WFC/JST July 25, 1990 Docket No.
STN 50-528/529/530 U.
S. Nuclear Regulatory Commission Attention:
Document Control Desk Mail Station Pl-37 Washington, D.
C.
20555
Reference:
(1)
Letter to NRC from W. F. Conway, Dated May 23, 1990;
Subject:
Status of Improvements to Eliminate the Possibility of Multiple CEA Drop Events (2)
Letter to NRC from W.
F.
- Conway, Dated October 25, 1989;
Subject:
"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
Status of "Justification for Continued Operation
- Control Element Assembly (CEA) Drop Events, Revision 3" File:
90-056-026 Reference (1) provided the status of improvements to minimize the possibility of multiple CEA drop events at PVNGS.
These improvements were outlined in the "Justification for Continued Operation
- Control Element Assembly (CEA) Drop
- Events, Revision 3 (JCO)," reference (2).
In order to keep you informed of our
- progress, the attachment to this letter provides an updated status of the corrective actions for your information.
As a result of the corrective actions taken to date on Units 1 and 2, the JCO is no longer required for those Units.
The PVNGS Plant Review Board approved the suspension of the JCO from Units 1 and 2 on June 8, 1990 after reviewing the root cause and corrective actions taken to date.
The PRB noted that the only outstanding corrective action, reversal of latch coil polarity, willbe completed at the next series of refueling outages and is being tracked as a regulatory commitment to ensure completion.
The reversal of the latch coil polarity will minimize liftcoil motion during CEA movement and improve long term coil life.
The completion of this corrective action is not required for continued operation since without the original manufacturing defect, damaged insulation on the coil lead wires, no grounding would be expected to occur even with coil motion.
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Nuclear Regulatory Commission Document Control Desk Page 2
161-03364-WFC/JST July 25, 1990 Please contact me if you have any questio'ns.'incerely, WFC/J ST/j le cc:
J.
B. Martin T. L. Chan D. H.
Coe A. H. Gutterman S.
R. Peterson E.
E. Van Brunt
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Attachment Status, of Corrective Actions Coil Sleevin To inspect coil insulation, replace defective coils, and sleeve all CEDM coil leads:
Units 1 and 2
- This action is complete.
Unit 3 - Inspection program to be performed at the next scheduled refueling outage.
Ground Fault Detection To assure continuous monitoring and annunciation of any future CEDM ground faults:
Units 1 and 2 - Modified ground fault detector installed and tested.
Unit 3 - Ground fault detector modification will be installed during next outage of sufficient duration.
Latch Coil Polarit Reversal Coupling of the lower latch and lift coil magnetic fields by reversing the polarity of the lower latch coil will minimize lower liftcoil motion:
Units 1, 2, and 3 - This design change willbe completed for implementation during the next series of refueling outages.
Status of Long Term Enhancements In the long term APS has received a proposal from Combustion Engineering to reduce the CEDMCS susceptibility to noise by modifying the Zero Crossing Detector Circuitry in the silicon controlled rectifier firing circuitry.
This proposal is currently being evaluated by APS Engineering.
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