ML17313A127

Special Rept 2-SR-97-002:on 971103,loose-part Detection Sys Channel 2 Declared Inoperable.Caused by Malfunction of Coaxial Cable Connector to accelerometer.Loose-part Detection Sys Channel Will Be Reworked

ML17313A127
Person / Time
Site:	Palo Verde
Issue date:	11/26/1997
From:	Overbeck G ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-01007-GRO-D, 192-1007-GRO-D, 2-SR-97-002, 2-SR-97-2, NUDOCS 9712090145
Download: ML17313A127 (7)

Text

CATEGORY REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9712090145 DOC.DATE: 97/11/26 NOTARIZED: NO DOCKET FACXL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 AUTH.NAME AUTHOR AFFILIATION OVERBECK,G.R. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 2-SR-97-002:on 971103,loose-part detection sys channel 2 declared inoperable. Caused by malfunction of coaxial cable connector to accelerometer. Loose-part detection sys channel will be reworked.

DISTRIBUTION CODE: IE22D COPIES RECEXVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

E NOTES:Standardized plant. 05000529 G

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 CLIFFORD,J 1 1 INTERNAL: ACRS 1 '

2 2 AEOD/SPD/RRAB 1 1 FILE NTER 1 1 NRR/DE/ECGB 1 1 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DET/EIB 1 1 RGN4 FILE 01 1 1 D EXTERNAL: L ST LOBBY WARD 1 1 LXTCO BRYCE,Q' 1 1 NOAC POORE,W. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 N

NOTE TO ALL "RIDS" 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 25 ENCL 25

ji II il

Gregg R. Overbeck Mail Station 7602 Pab Verde Nuclear Vice President TEL 602/393-5148 P.O. Box 52034 Generating Station Nuclear Production FAX 602I3934077 Phoenix, AZ 85072-2034 192-01007 - GRO/DGM/KR November 26, 1997 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 2 Docket No. STN 50-529 (License No. NPF-51)

Special Report 2-SR-97-002 Attached please find Special Report 2-SR-97-002 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 Daniel G. Marks, Section Leader, Nuclear Regulatory Affairs, at (602) 393-6492.

Sincerely, GRO/DGM/KR/mah Attachment cc: E. W. Merschoff (all with attachment)

K. E. Perkins J. H. Moorman INPO Records Center IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII I\

9712090145 97112b PDR ADQCK 05000529 8 PDR

. PALO VERDE NUCLEAR GENERATING STATION UNIT 2 Loose-Part Detection System License No. NPF-51 Docket No. STN 50-529 Special Report 2-SR-97-002 Initial Conditions:

At approximately 0650 MST on November 3, 1997, Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) operating at approximately 100 percent power when Loose-Part Detection System channel 2 was declared inoperable. The thirty day period for returning the channel to an operable status expired at approximately 0650 MST on December 3, 1997. 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 through Mode 2 (STARTUP).

S stem Information:

The Loose-Part Detection System is designed to detect and record signals from loose part impacts occurring within the Reactor Coolant System (RCS). The Loose-Part Detection System has eight (8) channels each using high temperature piezoelectric accelerometers (transducers) which are located in areas where loose parts are most likely to become trapped. The eight accelerometers are positioned on the reactor vessel upper head (channels 1 and 2), the lower. reactor vessel (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 preampliTiers which are located outside of the primary shield. The accelerometers 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.

Actions Taken:

On November 3, 1997, during routine daily monitoring as required by surveillance requirement 4.3.3.7.(a ), of the Loose-Part Detection System, Operations personnel determined that channel 2 was inoperable due to an intermittent failure of the signal.

Only limited. troubleshooting activities could be performed due to the radiological exposure which would be received because of the accelerometer'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.

Cause of the Malfunction:

The apparent failure of channel 2 is due to the malfunction of the coaxial cable connector to the accelerometer. The 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 2 problem due to the radiological exposure which would be received because of the accelerometer's location on the reactor vessel upper head. Modifications have been developed which will enhance the coaxial cable connectors and may prevent similar malfunctions. However, the implementation of these modifications is awaiting NRC approval of a TS change submittal.

Plans for Restorin the Channels to OPERABLE Status:

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 the remaining operable channels (i.e., during dayshift and nightshift).

1