ML17306A710

Special Rept:On 920504,Control Room Received Alarms on All Seven Control Boards.Plan Computer Returned to Svc & Was Declared operable.W/920506 Ltr

ML17306A710
Person / Time
Site:	Palo Verde
Issue date:	05/06/1992
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:
References
192-00783-JML-T, 192-783-JML-T, NUDOCS 9205120053
Download: ML17306A710 (7)

Text

ACCELERATED DISTRIBUTION DEMON/RATION SYSTEM I

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9205120053 DOC.DATE: 92/05/06 NOTARIZED: NO DOCKET FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME AUTHOR AFFILIATION LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

Special rept:on 920504,Control Room received alarms on all seven control boards. Plan computer returned to svc & was declared operable.W/920506 ltr. D DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR I ENCL j SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc. S NOTES:Standardized plant. 05000530 /

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD5 LA 1, 1' 1 PD5 PD 1 1 TRAMMELL,C THOMPSON,M 1 1 D INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB SD 1 1 NRR/DST/SICBSH3 1 1 N~RRJ3ST/SPLBSD1 1 1 NRR/DST/SRXB SE 1 1 CREG FI 02 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 3 3 L ST LOBBY WARD NRC PDR 1 1 NSIC MURPHY,G.A NSIC POOREiW 1 1 NUDOCS FULL TXT D

D D

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, =

ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 33 ENCL 33

Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX. ARIZONA 85072-2034 JAMES M. LEVINE 192-00783-JML/TRB/KR VICE PRESIDENT NUCLEAR PROOUCTION May 6, 1992 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Mail Station Pl-37 Washington, D.C. 20555

Dear Sirs:

Sub) ect: Palo Verde Nuclear Generating Station (PVNGS)

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

Special Report 3-SR-92-002 File'2-020-404 Attached please find Special Report 3-SR-92-002 prepared and submitted pursuant to Emergency Plan Implementing Procedure (EPIP-04). This report discusses a condition requiring the declaration of an ALERT due to an event resulting in a loss of most or all alarms (annunciators and computer) for greater than five minutes.

If you have any questions, please contact Thomas R. Bradish, Compliance Manager at (602) 393-5421.

Sincerely, JML/TRB/KR Attachment cc: W. F. Conway (all with attachment)

J. B. Martin D. H. Coe 9205120053 920506 PDR ADOCK 05000530 8 PDR

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Palo Verde Nuclear Generating 'Station Unit 3 Alert Docket No. 50-530 License No. NPF-74 Special Report No. 3-SR-92-002 This Special Report is being provided pursuant to Emergency Plan Implementing Procedure (EPIP-04), "Alert, Site Area, and General Emergency Implementing Actions" to report a condition requiring the declaration o'f an Alert for Palo Verde Unit 3 at approximately 0819 MST on May 4, 1992. The Alert was terminated at approximately 2321 MST on May 6, 1992.

On May 4, 1992, at approximately 0436 MST, Palo Verde Unit 3 was operating at approximately 100 percent power in Mode 1 (POWER OPERATION) when the Control Room received alarms on all seven control boards. At the time of the event, electricians were inspecting and verifying the type of alarm switch being used in the non-Class 1E 480 volt lighting load center (3ENGNL18) in accordance with an approved work document. The inspection and verification was being performed to ensure that the internal circuit breaker name plates correctly delineated the alarm switch configuration installed. The alarm switch provides an input into the 24 volt plant annunciator and the plant computer.

During this work evolution, a 24 volt lead contacted a non-Class 1E 480 volt bus resulting in the loss of the non-Class 1E Plant Annunciator System. At this time, the Plant, Monitoring System [i.e., the Core Monitoring Computer (CMC) and the plant computer (PC)j was still operational.

At approximately 0708 MST, Core Monitoring Computer Core Operating Limits Supervisory System (CMC COLSS) was declared inoperable. The Shift Supervisor entered Technical Specification (TS) Limiting Condition for Operation (LCO) 3.2.4 Departure from Nucleate Boiling Ratio (DNBR) Margin ACTION "c" which requires that the DNBR margin be maintained within limits using an operable Core Protection Calculator (CPC) channel. At approximately 0715 MST, Control Room personnel commenced performance of the appropriate surveillance requirements. At approximately 0749 MST, Control Room personnel commenced boration to reduce power in order to meet TS LCO 3.2.4 ACTION requirements.

By approximately 0819 MST, the plant computer performance had degraded to the point that it could not be relied upon. The Emergency Plan Implementing Procedure (EPIP-02), "Emergency Classification" requires the declaration of an Alert for an event resulting in a loss of most or all alarms (annunciators and computer) for greater than five minutes. Prior to this time, an Alert was not required in accordance with EPIP-02 because the plant computer monitoring capability was still available. Pursuant to EPIP-02, an Alert was declared at approximately 0819 MST. By approximately 0831 MST, on May 4, 1992, the appropriate state and local agencies had been notified of the condition requiring the declaration of an Alert (i.e., loss of annunciators and computer). The Nuclear Regulatory Commission (NRC) Operations Center was

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NRC Document Control Desk Special Report 3-SR-92-002 Page 2 notified at approximately 0830 MST on May 4, 1992. By approximately 0849 MST, reactor power had been reduced to approximately 74.5 percent power, satisfying the TS LCO 3.2 ' requirements, and TS LCO 3.2.4 ACTION "c" was exited.

Reactor power was subsequently stabilized at approximately 70 percent power.

Following troubleshooting and repair, the plant computer was returned to service, and at approximately 1447 MST CMC COLSS was declared operable. At approximately 1450 MST, PC COLSS was returned to service. Reactor power was maintained at approximately 70 percent power during troubleshooting and repair of the Plant Annunciator System. At approximately 2320 MST, the Plant Annunciator System was returned to service.

At approximately 2321 MST on May 6, 1992, the Alert was terminated in accordance with EPIP-04. By approximately 2322 MST on May 6, 1992, the appropriate state and local agencies and the NRC Operations Center were notified of the termination of the Alert.

At approximately 2340 MST, Unit 3 commenced a controlled plant shutdown to continue the plant annunciator testing and verification. Further investigation into the circumstances surrounding this event is being performed in accordance with the APS Incident Investigation Program.