ML17311A897

Special Rept:On 950416,loose-part Detection Sys Channel 1 Declared Inoperable.Caused by Malfunction of Coaxial Cable Connector to Transducer.Channel Will Be Reworked & Returned to Svc During First Available Outage of Sufficient Duration

ML17311A897
Person / Time
Site:	Palo Verde
Issue date:	05/25/1995
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-00932-JML-B, 192-932-JML-B, NUDOCS 9505310238
Download: ML17311A897 (8)

Text

RIORITY i ACCELERATE D Rl DS P ROC I'.SS I G REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9505310238 DOC.DATE: 95/05/25 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 Document Control Branch (Document Control Desk)

SUBJECT:

Special rept:.on 950416,loose-part detection sys channel 1 declared inoperable. Caused by malfunction of coaxial cable connector to transducer. Channel will be reworked & returned to svc during first available outage of sufficient duration.

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

J SIZE: 3 R

NOTES:Standardized plant. 05000530 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 THOMAS,C 1 J INTERNAL ACRS 1 1 2 2 AEOD/SPD/RRAB 1 1 F LE CENTER 1 1 NRR/DE/ECGB 1 1 /13E/EE 1 1 NRR/DE/EMEB 1 1 NRR/DISP/PIPB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 .1 NRR/DRCH/HOLB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SPSB/B 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 D

RGN4 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 U

N VOTE TO ALL"RIDS RECIPIENTS:

PLE:%SE IIELP I.'S TO RFDLCE KiSTE! CO.'iTiC I"I'III; DOCI.'ifl'i'I CO.'ASTROL DESk. ROOM PI-37 (EXT. 504- ~OS3 ) TO I;Ll ill i':i l'IOI.'R iAifLFllOif DISTRIBL'TIOiLIS'I S FOR DOC!.'ifL'i'I'S YOI. DOi "I'EI:

D'OTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

1 Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O, BOX 52034 ~ PHOENIX. ARIZONA 85072-2034 192-00932-JMUBAG/RAS JAMES M, LEVINE VICE PRESIOENT May 25, 1995 NUCLEAR PRODUCTION U. S. Nuclear Regulatory Commission A ITN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

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

Special Report 3-SR-95-001 Attached please find Special Report 3-SR-95-001 prepared and submitted pursuant to Technical Specification (TS) Limiting Condition for Operation 3.3.3.7 ACTION (a) and TS 6.9.2. This report discusses the inoperability of one (1) Loose-Part Detection System channel for more than thirty (30) days.

If you have any questions, please contact Burt Grabo, Section Leader, Nuclear Regulatory Affairs, at (602) 393-6492.

Sincerely, JML/BAG/RAS/rv Attachment cc: L. J. Callan (all with attachment)

K. E. Perkins K. E. Johnston 95053i0238 950525 PDR ADOCK 05000530 S PDR

PALO VERDE NUCLEAR GENERATING STATION UNIT 3 Loose-Part Detection System License No. NPF-74 Docket No. STN 50-530 Special Report 3-SR-95-001 Inii I nd

At approximately 0922 MST on April 16, 1995, Palo Verde Unit 3 was in Mode 1 (POWER OPERATION) operating at 100 percent power when Loose-Part Detection System channel 1 was declared inoperable. The thirty day period for returning the channel to an operable status was exceeded at approximately 0922 MST on May 16, 1995. This Special Report is being submitted pursuant to Technical Specification (TS) Limiting Condition for Operation (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 days. The remaining seven (7) channels continue to function properly. TS LCO 3.3.3.7 is applicable in Mode 1 and Mode 2 (STARTUP).

The Loose-Part Detection System is designed to detect and record signals resulting from loose part impacts occurring within the Reactor Coolant System (RCS). The Loose-Part Detection System has eight channels each utilizing high temperature piezoelectric accelerometers (transducers) which are located in areas where loose parts are most likely to become trapped.

The eight transducers are positioned on the Reactor Vessel upper head (channels 1 and 2),

the Reactor Vessel lower head (channels 3 and 4), Steam Generator No. 1 (channels 5 and 6) and Steam Generator No. 2 (channels 7 and 8). High temperature, low noise, radiation hardened, flame-retardant coaxial cables connect the accelerometers to preamplifiers which are located outside of the primary shield. The transducers detect 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 a "latch on" type alarm (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 alarm indicator in the Control Room for the eight channels.

On April 16, 1995, during routine daily monitoring of the of the Loose-Part Detection System, Operations personnel determined that channel 1 was INOPERABLE. This operability determination was preceded by recurrent losses of the signal, which became increasingly frequent until the channel was finally declared inoperable. Troubleshooting activities were not performed due to the radiological exposure which would be received because of the transducer's location on the Reactor Vessel upper head.

TS LCO 3.3.3.7 ACTION (a) was entered and applicable plant corrective action documents were initiated. During this time the other channels functioned normally.

The apparent failure of channel 1 is due to the malfunction of the coaxial cable connector to the transducer. This failure determination is based upon past failures of the cable connector to the accelerometer. An equipment root cause of failure analysis will not be performed to verify or rectify the Loose-Part Detection System channel 1 problem due to the radiological exposure which would be received because of the transducer's location on the Reactor Vessel upper head. However, modifications are being considered which will enhance the coaxial cable connectors and may prevent similar malfunctions.

The inoperable Loose-Part Detection System channel will be reworked and returned to service during the first available outage of sufficient duration. The remaining seven (7) channels continue to function properly. Shift Technical Advisors and Operations personnel will continue to perform shiftly aural checks on Channels 2 through 8 (i.e., during dayshift and nightshift).