ML17313A540

Special Rept:On 980715,declared PASS Inoperable.Caused by Failure of Offgas Flush/Purge Control Handswitch HS0101. Handswitch Replaced & Post Maintenance Retesting Was Initiated

ML17313A540
Person / Time
Site:	Palo Verde
Issue date:	08/13/1998
From:	Overbeck G ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-01025-GRO-D, 192-1025-GRO-D, NUDOCS 9808180337
Download: ML17313A540 (9)

Text

~CATEGORY 1 REGULATORY INFORMATION DISTRIBUTXON SYSTEM (RIDS)ACCESSION NBR:9808180337 DOC.DATE: 98/08/13 NOTARIZED:

NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH.NICE.AUTHOR AFFILIATION OVERBECK,G.R.

Arizona Public Service Co.(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Records Management Branch (Document Control Desk)

SUBJECT:

Special rept: on 980715,PASS dec;ared inoperable.

Caused by failure of offgas flush/purge control handswitch HS0101.Handswitch replaced&post maintenance retesting was ini tia ted.DISTRIBUTION CODE: IE22D COPIES RECEXVED:LTR ENCL SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.NOTES:STANDARDIZED PLANT E 0500052+RECIPXENT ID CODE/NAME PD4-2 PD COPIES RECIPIENT LTTR ENCL ID CODE/NAME 1 1 FIELDS,M COPIES LTTR ENCL 1 1 INTERNAL: ACRS AEOD/SPD/RRAB NRR/DE/ECGB NRR/DE/EMEB NRR/DRCH/HOHB NRR/DRPM/PECB RES/DET/EIB EXTERNAL: L ST LOBBY WARD NOAC POORE,W.NRC PDR 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 AEOD SPD RAB CE NRR/DRCH/HICB NRR/DRCH/HQMB NRR/DSSA/SPLB RGN4 FILE 01 LITCO BRYCE,Z H NOAC QUEENER,DS NUDOCS FULL TXT 2 2 1 1 1 1 1'1 1 1 1 1 1 1 1 1 1 1 1 D E N NOTE TO ALL"RZDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE.TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD)ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 23 ENCL 23 Canmllment

/nnnetkm.&erg'.Palo Verde Nuclear Generating Station Gregg R.Overbeck Vice President Nuclear Production TEL 602/3934148 FAX 602/3g34077 Mail Station 7602 P.O.Box 52034 Phoenix, AZ 85072-2034 1929025-GRO/DGM/DLK August 13, 1998 U.S.Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS)Unit1 Docket No.STN 50-528 License No.NPFQ1 Special Report 1 SR-98-002 Attached please find Special Report 1-SR-98-002 prepared and submitted pursuant to Technical Specification (TS)3.3.3.1 ACTION 28 and TS 6.9.2.This report discusses the inoperability of the Post Accident Sampling System for more than seven (7)days.In accordance with TS 6.9.2, a copy of this Special Report is being forwarded to the Regional Administrator, NRC Region IV.If you have any questions, please contact Daniel G.'Marks, Section Leader, Palo Verde Regulatory Affairs, at (602)393-6492.Sincerely, GRO/DGM/DLK/mah Attachments cc: E.W.Merschoff J.H.Moorman INPO Records Center (all with attachments) 9808i80337 9808i3 PDR ADOCK OS000528 8=PDR

, PALO VERDE NUCLEAR GENERATING STATION UNIT 1 Post Accident Sampling System License No.NPF-41 Docket No.STN 60-628 Special Report 1-SR-98-002 I'j t f't t PALO VERDE NUCLEAR GENERATING STATION UNIT 1 Post Accident Sampling System License No.NPFQ1 Docket No.STN 50-528 Special Report 1-SR-98-001 Initial Conditions:

At approximately 2137 MST on July 15, 1998, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION) operating at approximately 100 percent power when the Post Accident Sampling System (PASS)was declared inoperable.

The seven (7)day period for returning the PASS to operable status in accordance with Technical Specification (TS)3.3.3.1 Action 28 expired at approximately 2137 MST on July 22, 1998.This Special Report is being submitted pursuant to Technical Specification Limiting Condition For Operation (TS LCO)3.3.3.1 and TS 6.9.2 to report the inoperability of the PASS for more than seven (7)days.S stem Information The PASS is a subsystem of the Nuclear Sampling System designed to deliver a representative pressurized and depressurized reactor coolant and containment atmosphere sample under post accident conditions to the remote grab sampler.The PASS is capable of sampling during normal plant operating conditions to demonstrate system operability.

Actions Taken On July 15, 1998, during routine monthly surveillance testing of the PASS in accordance with TS surveillance requirement 4.3.3.1, the Offgas Flush/Purge Control handswitch HS0101 failed.Operations personnel declared the PASS, inoperable at approximately 2137 MST on July 15, 1998.The handswitch was replaced and post maintenance retesting was initiated.

At approximately 2230 MST on July 16, 1998, while testing the replaced handswitch, the PASS system overpressurized and a leak occurred in the low-pressure section of the PASS at pressure indicator PI0019.Troubleshooting activities identified a backpressure regulator (PCV0019)and a liquid sample valve (HV0019)had also failed.The PASS remained inoperable.

The failed pressure indicator, backpressure regulator, and the liquid sample valve were replaced and system integrity was verified.

t f II t t II i On JUly 22;1998, after completing the repairs on the PASS components that were damaged during the system overpressurization, Chemistry personnel again attempted to obtain a pressurized reactor coolant sample.White attempting to draw the reactor coolant sample,'the sample flask used for collecting the offgas would riot maintain the required vacuum.On July 22, 1998, at approximately 2100 MST, Operations personnel initiated the Pre-Planned Alternate Sampling Program in accordance with TS LCO 3.3.3.1 Action 28.Based on the troubleshooting results, the septum and the nitrogen purge isolation valve to the sample flask were replaced and on July 25, 1998, Chemistry personnel successfully obtained a pressurized reactor coolant sample.At approximately 1727.MST on July 25, 1998, Operations personnel exited TS LCO 3.3.3.1 Action 28 and declared PASS operable.Cause of the Ino erabili Failure of the Offgas Flush/Purge Control handswitch HS0101 initially caused the PASS to be declared inoperable.

Continued PASS inoperabililty, following the handswitch'epair, was caused by a system overpressurization event and the inability to maintain the required vacuum in the sample flask while attempting to obtain a pressurized reactor coolant sample after replacing the components that failed during the overpressurization event.These three events were all separate, independent events.The root cause of failure investigation for the overpressurization event is still ongoing.Plans and Schedule for Restorin the PASS to 0 erable Status The PASS was restored to operable status on July 25, 1998 at approximately 1727 MST; 0,'l 1 il t