ML17310A630

Special Rept 3-SR-93-003:on 930806,loose-part Detection Sys (Lpds) Declared Inoperable & Exceeded 30 Day Period for Being Returned to Svc on 930905.LPDS Channel 5 Scheduled to Be Reworked & Returned to Svc During Next Outage

ML17310A630
Person / Time
Site:	Palo Verde
Issue date:	09/13/1993
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-00861-JML-T, 192-861-JML-T, 3-SR-93-003, 3-SR-93-3, NUDOCS 9309220092
Download: ML17310A630 (8)

Text

ACCELERA"I'ED DOCUMENT DIS'I'RIBU'I'1ON SYSTEM REGULAtY INFORMATION DISTRIBUTISYSTEM (RIDE)

ACCESSION NBR:9309220092 DOC.DATE: 93/09/13 NOTARIZED: NO DOCKET ¹ FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME AUTHOR AFFILIATION LEVINEFJ.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 3-SR-93-003:on 930806,loose-part detection sys (LPDS) declared inoperable & exceeded 30 day period for being returned to svc on 930905.LPDS Channel 5 scheduled to D be reworked & returned to svc during next outage.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident pt,'tc.

NOTES:Standardized plant. 05000530 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PDV LA 1 1 PDV PD 1 1 TRANFT 1 1 TRAN,L 1 1 D

INTERNAL: ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 NRR~9A SPLB 1 1 NRR/DSSA/SRXB 1 1 RE IL 02 1 1 RES/DSIR/EIB 1 1

~ILE 01 1 1 EXTERNAL: EG&G BRYCEFJ.H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYFG.A 1 1 NSIC POOREFW. 1 1 NUDOCS FULL'XT 1 1 NOTE 'I'0 ALL "RIDS" RECIPIENTS:

PLIIASE I IEI.P US TO REDUCE WAS'I'I'! CON'I'ACI'lIL'OCU~iEN IAN'I'Iu3I. I)l:SI .

ROOI I Pl-37 (EX'I. 504-20(i5) TO ELlhliiATEYOl 'R NA.".lE PI<Oil l)IS'I'RIIII 'I'I: >N LISTS FOR DOCUMEN'I'S YOU DON"I'I'.ED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL 31

j' Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX, ARIZONA85072-2034 JAMES M., LEVINE 192-00861-JML/TRB/KR/rv VICE PRESIDENT NUCI.EAA PRODUCTION September 13,'993 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

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

Special Report 3-SR-93-003 File: 93-020-404 Attached please find Special Report 3-SR-93-003 prepared and submitted pursuant to Technical Specification 3.3.3.7 ACTION (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 T. R. Bradish, Manager, Nuclear Regulatory Affairs, at (602) 393-5421.

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

B. H. Faulkenberry J. A. Sloan q f'l ~ i 9309220092 930913 PDR ADOCK 05000530 S PDR

PALO VERDE NUCLEAR GENERATING STATION UNIT 3 Loose-Part Detection System ucense No. NPF-74 Docket No. 50-530 Special Report 3-SR-93403 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 2202 MST on September 5, 1993.

S stem Information:

The Loose-Part Detection System is designed to detect the presence of loose parts within the Reactor Coolant System. The Palo Verde Unit 3 Loose-Part Detection System consists of eight (8) channels. Each channel consists of a piezoelectric crystal monitor sensor 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 nozzfes (Channels 5, 6, 7, and 8). The piezoelectric sensors detect loose parts using acoustic signals which are generated when loose parts impact a Reactor Coolant System 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 wilt 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 the performance of the monthly CHANNEL FUNCTIONAL TEST specified in TS Surveillance Requirement (SR) 4.3.3.7.b, the Loose-Part Detection System channel 5 LED alarm indicator failed to illuminate when the TEST pushbutton was pressed.

Adjustments to channel 5, as specified in the surveillance testing procedure, failed to resolve the problem and the surveillance testing was terminated. At approximately 2202 MST on August 6, 1993, the Loose-Part Detection System was declared inoperable. Subsequent troubleshooting determined that the background noise was

,1

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Special Report 3-SR-93-003 Page 2 high enough to cause saturation in the amplifier making it impossible for the amplifier and comparator to respond to the additional test signal.

Cause of the Malfunction:

The background noise (i.e., mechanical resonance at approximately 12.8 KHz) is apparently due to the loosening of the Loose-Part Detection System accelerometer and/or its mounting plate to the RCS pipe. An equipment root cause of failure analysis cannot be performed to verify or to rectify the accelerometer mounting problem at the present operating mode due to industrial (i.e., high temperatures) and radiation safety concerns. A decision was made by PVNGS management to initiate compensatory actions (i.e., daily aural checks), enter the Technical Specification ACTION statement (i.e., prepare and submit a Special Report), and to repair the channel during the next outage.

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. Although the Loose-Part Detection System. channel remains inoperable, the channel is capable of being used to monitor for loose parts (i.e., aural checks). The remaining seven (7) channels continue to function properly at this time. During the period of inoperability, the STAs and Operations personnel will perform twice daily aural checks on Channels 1 through 8 (i.e., during dayshift and nightshift).

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