ML17306A221

Special Rept 2-SR-89-007-03:on 891002,fuel Bldg Ventilation Sys High Range Gaseous Effluent Monitor Declared Inoperable for More than 72 H.Caused by Low Flow Limit Switch Being Out of Adjustment.Microprocessor Operated Manual Mode

ML17306A221
Person / Time
Site:	Palo Verde
Issue date:	10/10/1991
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-00747-JML-T, 192-747-JML-T, 2-SR-89-007-03, 2-SR-89-7-3, NUDOCS 9110240185
Download: ML17306A221 (8)

Text

ACCELERATED DISTRIBUTION DEMONS TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9110240185 DOC.DATE: 91/10/10 NOTARIZED: NO DOCKET g 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-89-007-03:on 891002,fuel bldg ventilation sys high range gaseous effluent monitor declared inoperable for more than 72 h.Caused by low flow limit switch being out of adjustment. Microprocessor operated manual mode.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ( ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc. L SIZE:

I NOTES:Standardized plant. 05000529 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 TRAMMELL,C 1 1 THOMPSON,M 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H 1 1 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 NR~R DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 /DS 'LB8D1 1 1 NRR/DST/SRXB 8E 1 1 REG FIL 02 1 1 RES/DSIR/EIB 1 1 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 NOTES: 1 1 D

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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 35 ENCL 35

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Arizona Public Service Company .

PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX. ARIZONA 85072-2034 192-00747-JML/TRB/RKR JAMES M. LEVINE VICE PRESIDENT October 10, 1991 NUCLEAR PRODUCTION 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 2 Docket No. STN 50-529 (License No. NPF-51)

Special Report 2-SR-89-007-03 File'1-0 0-404 Attached please find Supplement 3 to Special Report 2-SR-89-007 prepared and submitted pursuant to Technical Specifications 3.3.3.8 ACTION 42(b) and 6.9.2.

This report discusses a radiation monitor being inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This supplement has been reformatted and provides the revised schedule for implementing the modification to correct flow problems discussed in this report. We are forwarding a copy of the Special Report to the Regional Administrator of the Region V office.

If you have any questions, please contact D. A. Johnson, Compliance Supervisor, at (602) 393-3703.

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

J. B. Martin D. H. Coe gqg'2 9iio~-4ois5 9iioio )Pp~

PDR PDR 8

PALO VERDE NUCLEAR GENERATING STATION UNIT 2 Radiation Monitoring Unit Inoperable for Greater Than 72 Hours License No. NPF-51 Docket No. STN 50-529 Special Report 2-SR-89-007-03 nitial Conditio s:

This Special Report is being submitted pursuant to Technical Specification (TS) 3.3.3.8 ACTION 42(b) and TS 6.9.2 to report an event in which the Fuel Building Ventilation System High Range Radioactive Gaseous Effluent Monitor (RU-146) was inoperable for a period greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period for returning the monitor to service was exceeded at approximately 0305 MST on October 2, 1989. On September 29, 1989, Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) at approximately 100 percent power.

Back round Information:

Radiation Monitors RU-145 (Fuel Building Ventilation System Low Range Radioactive Effluent Monitor) and RU-146 monitor the Fuel Building Ventilation Exhaust for release of radioactivity due to a fuel handling accident.

Radiation Monitors RU-145 and RU-146 work as a pair with RU-145 being the low range monitor for normal radioactive gaseous effluents and RU-146 being the high range monitor for post-accident radioactive gaseous effluents. Normal configuration consists of RU-145 operating and RU-146 in standby. When RU-145 reaches a predetermined setpoint, RU-146 starts and RU-145 goes to standby.

RU-145 initiates a Fuel Building Essential Ventilation Actuation Signal (FBEVAS) when the activity exceeds a predetermined setpoint, RU-146 starts and RU-145 goes to standby. RU-145 initiates a Fuel Building Essential Ventilation Actuation Signal (FBEVAS) when the activity exceeds a predetermined limit. Since RU-145 and RU-146 work in tandem, RU-146 must be declared inoperable if RU-145 is out of service.

On September 29, 1989, at approximately 0305 MST, the Fuel Building Ventilation System Radioactive Gaseous Effluent Monitors (RU-145 and RU-146) were declared inoperable due to frequent low flow alarms on the radiation monitor sample flow. The problem was discovered by control room personnel.

Alternate sampling was initiated in accordance with the Preplanned Alternate Sampling Program to monitor the Fuel Building Ventilation System fulfilling TS 3.3.3.8 ACTIONS 36, 37, 40 and 42, as applicable. An authorized work document was issued to troubleshoot and rework or replace components, as necessary, to correct the low flow alarms.

Cause of the Ino erabilit The initial investigation of the radiation monitors inoperability revealed that a majority of the low flow alarms were a result of actual low flow

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NRC Document Control Desk Special Report 2-SR-89-007-03 Page 2 conditions due to the low flow limit s~itch being out of adjustment. The limit switch was readjusted in accordance with an approved procedure. The cause of the remaining low flow alarms was due to the radiation monitor's microprocessor operating on instantaneous flow which resulted in process flow signal oscillations, sample flow oscillations, and process flow signal inconsistencies. No component failures were identified and all components were found to be working within their design capabilities.

lans a d Sc edu e or Restorin the S stem to Se ce:

As short term corrective action, the microprocessor is being operated in the manual process flow control mode to reduce the oscillations. Radiation monitors RU-145 and RU-146 were returned to service at approximately 1735 MST on January 27, 1990. As long term corrective action, a modification has been developed to correct the flow problems that resulted in the low flow alarms discussed above. The modification has been completed in Units 2 and 3. The modification is expected to be completed in Unit 1 by October 15, 1991.

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