ML17310A870

Special Rept 1-SR-93-006:on 931224,30 Day Period for Returning loose-part Detection Sys (Lpds) to Operable Status Exceeded.Inoperable Lpds Channel Scheduled to Be Reworked & Returned to Svc During Next Outage of Sufficient Duration

ML17310A870
Person / Time
Site:	Palo Verde
Issue date:	12/25/1993
From:	LEVINE J M ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1-SR-93-006, 1-SR-93-6, 192-00877-JML-B, 192-877-JML-B, NUDOCS 9401060073
Download: ML17310A870 (4)

Text

ACCELERATED DISTRIBUTION DEMONSiATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)ACCESSION NBR:9401060073 DOC.DATE: 93/12/25 NOTARIZED:

NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH.NAME AUTHOR AFFILIATION LEVINE,J.M.

Arizona Public Service Co.(formerly Arizona Nuclear Power RECIP.NAME

, RECIPIENT.

AFFIL'IATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 1-SR-93-006:on 931224,30 day period for returning loose-part detection sys (LPDS)to operable status exceeded.Inoperable LPDS channel scheduled to be reworked 6 returned to svc during next outage of sufficient duration.DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.-D NOTES:STANDARDIZED PLANT RECIPIENT ID CODE/NAME PDV LA HOLIAN,B INTERNAL: ACRS AEOD/DS P/TPAB NRR/DE/EELB NRR/DORS/OEAB NRR/DRCH/HICB NRR/DRI L/RPEB NRR/DSS SPLB G F~E 02 GN5 FILE 01 EXTERNAL: EGGG BRYCE,J.H NRC PDR NSIC POOREiW COPIES LTTR-ENCL 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1-.1 1 RECIPIENT ID CODE/NAME PDV PD TRAN,L AEOD/DOA AEOD/ROAB/DS P~NRR/DE/EMEB NRR/DRCH/HHFB NRR/DRCH/HOLB NRR/DRSS/PRPB NRR/DSSA/SRXB RES/DSIR/EIB L ST LOBBY WARD NSIC MURPHY,G.A NUDOCS FULL TXT COPIES LTTR ENCL 1 1 1'1 1 2 2 1 1 1 1.1 1 2 2 1'1 1 1 1 1 1 1 1 05000528 A D D D NOTE TO AI.L"RIDS" RECIPIENTS:

D D PLEASE HELP US TO REDUCE iVASTE!CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT.20079)TO ELliVIINATE YOUR NAME FROiM DISTRIBUTION LIS1S FOR DOCUMEiVSS YOU DON'T NEED!TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL 31 JAMES M.LEVINE VICE PRESIDENT NUCLEAR PRODUCTION Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O.BOX 52034~PHOENIX.ARIZONA 85072-2034 192-00877-JML/BAG/PMM December 25, 1993 U.S.Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)Unit 1 Docket No.STN 50-528 (Ucense No.NPF&1)Special Report 1&R-93~File: 93-02&404 Attached please find Special Report 1-SR-93-006 prepared and submitted pursuant to Technical Specification 3.3.3.7 ACTlON (a)and Technical Specification 6.9.2.This report discusses the inoperability of one (1)Loose-Part Detection System channel for more than thirty (30)days.lf you have any questions, please contact Burt Grabo at (602)393-6492.Sincerely, Ay.~JML/BAG/PMM/pm Attachment cc: W.F.Conway (all w/attachment)

B.H.Fauikenberry K.E.Johnston ,II"I t!i..V'i.L 9401060073 93i 225 PDR ADOCN 05000528 S PDR PALO VERDE NUCLEAR GENERATlNG STATION UNIT 1 Loose-Part Detection System License No.NPF<1-Docket No.50-528 Special Report 1R-93~Initial Conditions:

This Special Report is being submitted pursuant to Technical Specification Limiting Condition for Operation (TS LCO)3.3.3.7 ACTION (a)and TS 6.9.2 to report the inoperability of one (1)Loose-Part Detection System channel for more than thirty (30)days.The remaining seven (7)channels continue to function properly.TS LCO 3.3.3.7 is applicable in Mode 1 (POWER OPERATION) and Mode 2 (STARTUP).

The thirty (30)day period for returning the channel to an operable status was exceeded at approximately 0356 MST on December 24, 1993.S stem Information:

The Loose"Part Detection System is designed to detect the presence of loose parts within the Reactor Coolant System (RCS).The Palo Verde Unit 1 Loose-Part Detection System consists of eight (8)channels.Each channel consists of a piezoelectric accelerometer and associated amplification, indication, and recording.circuitry.

The eight (8)sensors are positioned in the following locations:

two (2)mounted on the Reactor Vessel upper head (Channels 1 and 2), two (2)mounted on the Reactor Vessel lower incore nozzle (Channels 3 and 4), and one (1)on each of the two (2)Steam Generators'nlet and outlet nozzles'(Channels 5, 6, 7, and 8).The accelerometer detects loose parts using acoustic signals which are generated when loose parts impact an RCS component or structure.

Signals in excess of the alarm setpoint will result in an alarm condition.

The alarms are the"latch on" type (i.e., the alarm will remain on when the system returns to normal and will not clear until the alarm is manually reset).There is one (1)alarm indicator in the Control Room for the eight (8)channels.Actions Taken: During a routine surveillance test, the Unit 1 Shift Technical Advisor reported that the Loose-Part Detection System Channel 1 failed to respond as required (the system is monitored every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />).During initial troubleshooting by APS Maintenance, it was believed that the connector cable to the accelerometer was intermittent.

At approximately 0356 MST on November 24, 1993, the Loose-Part Detection System was declared inoperable.

Special Report 1-SR-93-006 Page 2 Cause of the Malfunction:

The failure of Channel 1 is apparently due to the connector being intermittent.

The most probable caus~of the connector being intermittent is damage from accelerometer removal to access the vessel head.Past experience and the type of testing carried out supports this conclusion.

An equipment root cause of failure analysis cannot be performed to verify or to rectify the Loose-Part Detection System channel problem due to industrial (i.e., high temperatures) and radiation safety concerns.A decision was made by PVNGS management to enter the Technical Specification ACTION statement (i.e., prepare and submit a Special Report), and to repair the channel during the next outage of sufficient duration.Plans for Restorin the Channel to OPERABLE Status: The inoperable Loose-Part Detection System channel is scheduled to be reworked and returned to service during the next outage of sufficient duration.Restoration of the channel will include replacement of the accelerometer and cabling.Currently, Channel 1 is incapable'of being used to monitor for loose parts;however, the remaining seven (7)channels continue to function properly.