ML17304A366

Special Rept 3-SR-88-004:on 880725,reactor Vessel Water Level Sys Channel B Declared Inoperable.Caused by Previous Failures on 880219 & 0706 of Malfunctioning Heated Junction Thermocouples Mechanism.Channel Will Be Restored

ML17304A366
Person / Time
Site:	Palo Verde
Issue date:	08/22/1988
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
192-00404-JGH-T, 192-404-JGH-T, 3-SR-88-004, 3-SR-88-4, NUDOCS 8808290250
Download: ML17304A366 (5)

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. $C CELEMTZD DISTRIBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8808290250 DOC.DATE: 88/08/22 NOTARIZED: NO DOCKET FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME AUTHOR AFFILIATION HAYNES,J.G. Arizona Nuclear Power Project (formerly Arizona Public Serv RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 3-SR-88-004 re inoperable reactor vessel water level sys channel.

DISTRIBUTION CODE- IE22D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:Standardized plant. 05000530 8

RECIPIENT COPIES 'RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 LICITRA,E 1 1 DAVIS,M 1 1 A INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB 2 2 AEOD/DS P/TPAB 1 1 ARM/DCTS/DAB 1 1 DEDRO 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 NRR/DOEA/EAB NRR/DREP/RPB 10 ll 1 1

2 1

1 2

NRR/DLPQ/QAB NRR/DREP/RAB gfRR/BR-10 10 SIB 9A 1

1 1

1 1

1 NUDOCS-ABSTRACT RES TELFORD,J 1 1 I 02 1 1 1 1 R DEPY 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EG&G WILLIAMS,S 4 4 FORD BLDG HOY,A 1 1 H ST- LOBBY WARD 1 1 LPDR 1, 1 NRC PDR 1 1 NSIC HARRIS,J 1' NSIC MAYS,G 1 1 NOTES 1 1 A

D TOTAL NUMBER OF COPIES REQUIRED: LTTR 48 ENCL 47

Arizona Nuclear Power Project P.O. BOX 52034 ~ PHOENIX, ARIZONA 85072-2034 192-00404-JGH/TDS/DAJ

~

August 22, 1988 U. S. Nuclear Regulatory Commission NRC Document Control Desk Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 3 Docket No. STN 50-530 (License No. NPF-74)

Special Report 3-SR-88-004 File: 88-020-404

, Attached please find Special Report 3-SR-88-004 prepared and submitted pursuant to Technical Specifications 3.3.3.6 Table 3.3-10, ACTION 31. This report discusses an inoperable Reactor Vessel Water Level System Channel.

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

Very tru y yours, PA J. G. Ha nes Vice President Nuclear Production JGH/TDS/DAJ/kj Attachment cc: D. B. Karner (all w/a)

E. E. Van Brunt, Jr.

J. B. Martin T. J. Polich M. J. Davis A. C. Gehr INPO Records Center SSOS290250 SSOS22

/ ,gC "ti PDR ADOCK 05000530 PDC

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Palo Verde Nuclear Generating Station Unit 3 Channel "B" Reactor Vessel Water Level System Inoperable License No. NPF-74 Docket No. 50-530 Special Report No. 3-SR-88-004 Pursuant to Post Accident Monitoring Instrumentation Technical Specification 3.3.3.6 Table 3.3-10, ACTION STATEMENT 31, this submittal provides the required Special Report for the inoperability of one channel of the Reactor Vessel Water Level System (RVWLS) for a period of greater than seven (7) days. 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.'n order for each channel to be operable, two or more of the upper four sensors and two or more of the lower four sensors must be functional.

Prior to the conditions described in this Special Report, HJTC's 5 and 6 had malfunctioned on February 19, 1988 and HJTC's 3 and 4 had malfunctioned on July 6, 1988. 'ANPP has experienced reliability problems with the RVWLS "in all three units and is currently investigating the root cause of failure mechanism for a failed channel obtained from Unit 1.

On July 25, 1988 Palo Verde Unit 3 was operating at approximately 95 percent power. At approximately 0221 MST during the performance of surveillance testing on the gualified Safety Parameter Display System, it was discovered that Channel "B" indication for RVWLS levels 7 and 8 were not operating properly. Since HJTC's 5 and 6 had malfunctioned in February 1988 (HJTC's 5, 6, 7 and 8 are the four sensor in the lower half), RVWLS Channel "B" was declared inoperable. An approved work document was initiated to determine the cause of the improper operation and to perform the necessary rework to return the channel to service. During the troubleshooting, it was discovered that HJTC's 7 and 8 had malfunctioned and repairs could not be effected until the next scheduled refueling outage.

The root cause of failure initiated as a result of the previous failures will address the failure mechanism for the malfunctioning HJTC's in Unit 3. The RVWLS Channel "B" is scheduled to be restored to service during Unit 3's next scheduled refueling outage.