ML17304B245

Special Rept 3-SR-88-007-01:on 881024,inoperability of Both Channels of Reactor Vessel Water Level Sys Occurred for Period of Greater than 48 H.Caused by Malfunctioning of Communications Board.Replacement Board Installed

ML17304B245
Person / Time
Site:	Palo Verde
Issue date:	06/05/1989
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:
References
192-00487-JGH-T, 192-487-JGH-T, 3-SR-88-007-01, 3-SR-88-7-1, NUDOCS 8906140097
Download: ML17304B245 (8)

Text

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ACCESSION NBR:8906140097 DOC.DATE: 89/06/05 NOTARIZED: NO DOCKET FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME 'UTHOR AFFILIATION HAYNES,J.G. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

Special Rept 3-SR-88-007-01:on 881024 reactor vessel water level sys inoperable for more than 48 h.

DISTRZBUT10N CODE: ZE22D COPIES RECEIVED:LTR / ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

J SIZE NOTES:Standardized plant. 05000530 RECIPIENT COPIES RECIPIENT COPIES ZD CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 DAVIS,M.J. 1 1 DAVIS,M 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 DEDRO 1 1 IRM/DCTS/DAB 1 1 NRR/DEST/ADE 8H 1 1 NRR/DEST/ADS 7E 1 0 NRR/DEST/CEB 8H 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H 1 1 NRR/DEST/MTB 9H 1 1 NRR/DEST/PSB 8D 1 1 NRR/DEST/RSB 8E 1 1 NRR/DEST/SGB 8D 1 1 NRR/DLPQ/HFB 10 1 1 NRR/DLPQ/PEB 10 1 1 NRR/DOEA/EAB 11 1- 1 NRR/DREP RPB 10 2 2 NUDOCS-ABSTRACT 1 1 ~E.:~l~~ 1 1 RES/DSIR/EIB 1 1 RES/DSR/PRAB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EGGG WILLIAMS,S 4 4 FORD BLDG HOY,A 1 1 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHYiG.A 1 1 NOTES: 1 1 NOIE 'ZO ALL 'RZDS" RECIPIENIS:

PIZASE HELP US ZO REMCB %ASTE! CXNZACT 'IHE DOQ3MEÃI'ONTROL DESK, ROC'l-37 (EXT. 20079) KO EZJÃZNl68 VDGR SAME PKH DIPTRIH)TICN LZSTS KHt DOCXlMEMZS VXJ DCÃ!T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 45 ENCL 44

Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P 0 BOX 52034 ~ PHOENIX. ARIZONA 85072 2034 192-00487-JGH/TDS/DAJ June 5, 1989 U.S. Nuclear Regulatory Commission NRC Document Control Desk Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station Unit 3 Docket No. STN 50-530 (License NPF-74)

Supplement to Special Report 3-SR-'88-007-01 File: 89-020-404 Attached please find Supplement 1 to Special Report 3-SR-88-007 prepared and submitted pursuant to Technical Specification 3.3.3.6, Table 3.3-10, ACTION

32. This report discusses an inoperable Reactor Vessel Water Level System.

If you have any questions, please contact T. D. Shriver, Compliance Manager at (602) 393-2521.

Very trul yours,-

vg J. G. Haynes Vice President Nuclear Production JGH/TDS/DAJ/kj Attachment cc: W. F. Conway (all w/a)

D. B. Karner E. E. Van Brunt, Jr.

T. J. Polich M. J, Davis A. C. Gehr INPO Records Center 8906140097 890605 PDR ADOCK 05000530 S PNU

,7 PALO VERDE NUCLEAR GENERATING STATION UNIT 3 Both Channels of the Reactor Vessel Water Level System Inoperable License No. NPF-74 Docket No. 50-530 Special Report No. 3-SR-88-007-01 This Special Report is being submitted pursuant to Post Accident Monitoring Instrumentation Technical Specification 3.3.3.6, Table 3.3-10, ACTION STATEMENT 32 to report the inoperability of both channels of the Reactor Vessel Water Level System (RVWLS) for a period of greater than forty-eight (48) hours. The forty-eight hour time period expired on October 24, 1988 at approximately 1752 MST. RVWLS consists of two channels ("A" and "B"). Each channel utilizes eight (8) heated junction thermocouples (HJTC) to generate the signals for 8 indicated levels. There are four HJTC's in the Reactor Vessel head region and four HJTC's in the Reactor Vessel outlet plenum. HJTC output signals are processed to provide indication of reactor vessel water level. Level indication is provided on the gualified Safety Parameter Display System (gSPDS).

As previously discussed in Special Report 3-SR-88-004 issued on August 22, 1988, RVWLS Channel "B" has been inoperable since July 25, 1988. On October 22, 1988 at approximately 1752 MST, Palo Verde Unit 3 was operating at approximately 100 percent power when gSPDS channel "A" was noted to be operating improperly and declared inoperable. As a result of gSPDS Channel "A" inoperability, RVWLS Channel "A" indication was not available and consequently also became inoperable.

An approved work document was initiated to determine the cause of the improper gSPDS operation and to perform the necessary rework to return gSPDS Channel "A" to service. During troubleshooting, it was identified that a communications board was malfunctioning. A replacement communications board was not immediately available on-site and efforts were undertaken to obtain a replacement board. On October 28, 1988 a replacement communications board was obtained and installed.

Following the installation of the new communications board, it was noted that the Emergency Response Facilities Data Acquisition and Display System (ERFDADS) data link with gSPDS was not operating properly. Troubleshooting could not determine the cause of the malfunction; however, since ERFDADS is not necessary for gSPDS and/or RVWLS operability, the troubleshooting efforts were terminated in order to return RVWLS to service. Further troubleshooting will be conducted in accordance with an approved work document during Unit 3's first refueling outage.

Appropriate retesting was performed on gSPDS channel "A" and it was declared operable at approximately 2002 MST on October 28, 1988. gSPDS and RVWLS were inoperable for approximately six days, two hours and ten minutes.

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Special Report -007-001 Page 2 A Root Cause of Failure engineering evaluation was performed for the malfunctioning gSPDS channel "A" communications board. APS engineering personnel examined the communications board at the PVNGS rework facility.

Several of the boards sub-components were tested and discovered to be operating properly. No cause for the malfunction could be determined. The type of board malfunction is the first that has occurred. Future communications board malfunctions will be trended to identify potential system problems.