ML17305A996

Special Rept 2-SR-89-009:on 891212,Channel a Reactor Vessel Water Level Sys Declared Inoperable & 7-day Limit Exceeded on 891219.Modem Found to Have Drifted Out of Tolerance. Channel a Modem Replaced & Calibr

ML17305A996
Person / Time
Site:	Palo Verde
Issue date:	08/09/1990
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-00683-JML-R, 192-683-JML-R, 2-SR-89-009, 2-SR-89-9, NUDOCS 9008130261
Download: ML17305A996 (8)

Text

ACCELERATED DI~BUTION DEMONSTRTION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9008130261 DOC.DATE: 90/08/09 'NOTARIZED: NO 'OCKET FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi . 05000529 AUTH. NAME AUTHOR AFFILIATION LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 2-SR-89-009:on 891219,reactor vessel water level sys inoperable for more than 7 days.

DISTRIBUTION CODE: IE22D D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc. S NOTES:Standardized plant. 05000529 RECIPIENT COPIES RECIPIENT COPIES A ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 D PETERSON,S. 1 1 TRAMMELL,C. 1 1 D

INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 NRR DST SPLB8D1 1 1 NRR/DST/SRXB 8E 1 1 02 1 1 RES/DSIR/EIB 1 1 FILE 01 1 1 EXTERNAL EG&G BRYCE g J ~ H 3 3 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 R

NOTES 1 1 D

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D NOTE TO ALL "RIDS" REClPIENTS:

PLEASE HELP US TO REDUCE AVASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOK! Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 36 ENCL 36

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Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P,O, BOX 52034 ~ PHOENIXARIZONA85072-2034 192-00683-JHL/TRB/RKR JAMES M, LEVINE August 9, 1990 VJDE PRESIDENT NVCt.ERA PRODUCTION U. S. Nuclear Regulatory Commission Attention: Document Control Desk Mail Station Pl-37 Washington, DC 20555

Dear Sirs:

Subj ect: Palo Verde Nuclear Generating Station (PVNGS)

Unit 2 Docket No. STN 50-529 (License No. NPF-51)

Special Report 2-SR-89-009 File: 90-020-404 Attached please find Supplement 1 to Special Report 2-SR-89-009 prepared and submitted pursuant'to Technical Specifications 3.3.3.6 ACTION 31 and 6.9.2. This report discusses the inoperabi.lity of one channel of the Reactor Vessel Water Level System and updates the schedule for returning the system to OPERABLE status.

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

Very truly yours, JML/TRB/RKR/dmn Attachment cc: W. F. Conway (all with attachment)

J. B. Martin D. H. Coe C. M. Trammell A. C. Gehr A. H. Gutterman

I5 PALO VERDE NUCLEAR GENERATING STATION Reactor Vessel Water Level System Inoperable for Greater Than 7 Days License No. NPF-51 Docket No. STN 50-529 Special Report No. 2-SR-89-009-01 Pursuant to Post Accident Monitoring Instrumentation Technical Specification 3.3.3.6 Table 3.3-10, ACTION 31 and 6'.9.2, 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.

At approximately 0915 MST on December 12, 1989, RVWLS Channel "A" was declared inoperable. The seven (7) day limit for returning the channel of RVWLS to an operable status was exceeded at approximately 0915 MST on December 19, 1989.

RVWLS consists of two channels ("A" and "B"). Each channel uses eight (8) heated junction thermocouples (HJTC) to generate the signals for eight (8) indicated levels. There are four (4) HJTC's in the reactor vessel head region and four HJTC's in the reactor vessel outlet plenum. For each channel to be operable, two or more of the upper foug sensors and two or more of the lower four sensors must be functional. HJTC output signals are processed to provide indication of reactor vessel water level. RVWLS indication is displayed on the Quality Safety Parameter Display System (QSPDS) ~

At'approximately 0915 MST on December 12, 1989, Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) at approximately 100 percent power when QSPDS Channel "A" could not be calibrated in accordance with an approved procedure and was declared inoperable. As a result of QSPDS Channel "A" inoperability, RVWLS Channel "A" indication was not available and consequently was inoperable. An approved work authorization document was initiated to determine the cause of the QSPDS inoperability and to perform the necessary rework to return QSPDS Channel "A" to service. During troubleshooting to determine the cause of the QSPDS malfunction, it was determined that the Channel "A" modem was not operating properly and had drifted out of tolerance. The QSPDS'hannel "A" modem was replaced and calibrated in accordance with an approved work authorization document. QSPDS Channel "A" was returned to operable status at approximately 2228 MST on December 26, 1989. QSPDS was inoperable for approximately 14 days, 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and 13 minutes.

At approximately 1410 MST on December 15, 1989, a trouble alarm was received for the power supply to Channel "A" HJTC's number 5, 6, 7, and 8. 'n approved work authorization document was initiated to determine the cause of the RVWLS Channel "A" power supply trouble alarm. The troubleshooting determined that there was a ground in the heater 'for Channel "A" HJTC number 6. The power supply trouble alarm cleared when the breaker to the heater was opened, isolating the ground from the power supply. The heaters for HJTC's "A" number 5, 7, and 8 are also powered through this breaker. Therefore Channel lower

I NRC Document Control Desk Special Report 2-SR-89-009-01 Page 2 HJTC's number 5, 6, 7, and 8 were not functional. As a result, RVWI.S Channel "A" was also inoperable bec'ause more than two (2) lower sensors (4 total) were inoperable in RVWLS Channel "A".

II Unit 2 shutdown for the scheduled refueling outage on February 23, 1990.

Troubleshooting during the Unit 2 refueling outage determined the ground on the heater for HJTC number 6 was internal to the HJTC and could not be repaired. A temporary modification was installed which separated the heater for HJTC number 6 from the, power supply for channel "A" HJTC's number 5, 7, and 8 allowing the heaters for HJTC's 5, 7, and 8 to be energized.

Testing was performed on the HJTC's after they were reinstalled during the refueling outage. The testing determined that the heaters for channel "A" HJTC's 5 and 8 were also inoperable. Therefore, channel "A" lower HJTC's number 5, 6, and 8 were not functional. As a result, RVWLS channel "A" was still inoperable. At that time there were no spare HJTCs available to replace the channel "A" HJTC. Spare HJTCs had been ordered prior to this event when the remaining spare HJTCs were used in Unit 1. The delivery date for the spare HJTCs is November 1990. The delivery schedule, incl'uding expediting the delivery date, did not support replacement of the HJTC during the Unit 2 refueling outage. The Unit 2 refueling outage ended on July 19, 1990. TS 3.3.3,6 ACTIONS 31 and 32 allow continued operation with one or more channels of RVWLS inoperable if repairs are not feasible without shutting down. TS 3.3.3.6 also allows MODE changes with RVWLS inoperable. Therefore, RVWLS channel "A" will be returned to OPERABLE status during the next Unit 2 refueling outage. An approved procedure is also available to Control Room personnel for monitoring reactor vessel inventory with RVLMS inoperable.

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