ML17303A516

Special Rept 2-SR-87-021:on 870620,noble Gas Activity Monitor RU-141 Experienced Microprocessor Lockup.Cause Unknown.Troubleshooting Conducted to Reset Central Processing Unit to Remove Monitor from Lockup

ML17303A516
Person / Time
Site:	Palo Verde
Issue date:	07/17/1987
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
2-SR-87-021, 2-SR-87-21, NUDOCS 8707290384
Download: ML17303A516 (4)

Text

REGULAT Y INFORMATION DISTRIBUTION SYSTEM (RIDS)ACCESSION NBR: 8707290384 DOC.DATE: 87/07/17 NOTARIZED:

NO'OCKET 0 FACIL: STN-50-529 Palo Verde Nuclear Stations Unit.2, Ari'zona Pub li 05000529 AUTH.NAME AUTHOR AFFILIATION HAYNES, J.G.Ari zona Nuclear Poeer Prospect (formerly AT i zona Public Serv REC IP.NAME RECIPIENT AFFILIATION

SUBJECT:

Special Rept 2-SR-87-021:

on 870620'oble gas activitg monitor RU-141 experienced microprocessor lockup.Cause unknoUjn.Troubleshooting conducted to reset central processing unit to remove monitor from lockup.DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR ENCL SIZE: TITLE: 50.73 Licensee Event Report,(LER)i Incident Rpti etc.NOTES: Standard i z ed p lant.M.Davi si NRR: ICE.0500052m RECIPIENT ID CODE/NAME PD5 LA LICITRA E INTERNAL: ACRS MICHEI SON AEOD/DOA AEOD/DSP/ROAB DEDRO NRR/DEST/ADS NRR/DEBT/ELB NRR/DEBT/MEB NRR/DEBT/PSB NRR/DEST/SGB NRR/DLPG/GAB NRR/DREP/RAB RB R FILE 02 ORDs J RGN5 FILE 01 COP IES LTTR ENCL 1 1 1 1 1 1~1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 RECIPIENT ID CODE/NAME PD5 PD DAVIS'ACRS MOELLER AEOD/DSP/NAS AEOD/DSP/TPAB NRR/DEST/ADE NRR/DEST/CEB NRR/DEST/ICSB NRR/DEST/MTB NRR/DEST/RSB NRR/DLPG/HFB NRR/DOEA/EAB NRR/DREP/RPB NRR/PMAS/PTSB RES DEPY QI RES/DE/EIB COPIES LTTR ENCL 1 1 1 1 2 2 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 EXTERNAL: EGhG GROHi M LPDR NSIC HARRIS>J NOTES: 5 5 1 1 1 1 1 1 H ST LOBBY WARD NRC PDR NSIC MAYSz G 1 1 1 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 47 ENCL 45

Arizona Nuclear Power Project P.O.BOX 52034~PHOENIX.ARIZONA 85072-2034 192-00241-JGH-TRB/ESP July 17, 1987 U.S.Nuclear Regulatory Commission NRC Document Control Desk Washington, D.C.20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)Unit 2 Docket No.STN 50-529 (License NPF-51)Special Report 2-SR-87-021 File: 87-020>>404

Dear Sirs:

Attached please find a Special Report 2-SR-87-021 prepared and submitted pursuant to Technical Specifications 3.3.3.8 and 6.9.2.This report discusses radiation monitoring units inoperable f~r greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.If you have any questions, please contact T.R.Bradish, Compliance Supervisor at (602)393-5000, Ext.6936.Very truly yours,.gi-j/c"e~Mp J.G.Haynes Vice President Nuclear Production JGH/TRB/ESP/cld Attachment cc: 0.M.DeMichele (all w/a)E.E.Van Brunt, Jr.J.B.Martin R.P.Zimmerman R.C.Sorenson E.A.Licitra A.C.Gehr INFO Records Center 8707290384 870717 PDR ADOCK 05000529 S PDR PALO VERDE NUCLEAR GENERATING STATION RADIATION MONITORS INOPERABLE FOR GREATER THAN 72 HOURS License No.NPF-51 Docket No.STN 50-529 Special Report No.2-SR-87-021 This Special Report is being submitted pursuant to Technical Specification (T.S.)3.3.3.8 ACTION 42b and T.S.6.9.2 to report an event in which low and high range noble gas activity monitors (RU-141 and RU-142)were inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limit for operability was exceeded at approximately 2040 MST on June 23, 1987.Pursuant to T.S.3.3.3.8 ACTION 42a the Preplanned Alternate Sampling Program was initiated to monitor the plant ventilation system.At approximately 2040 MST, on June 20, 1987 Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) at 100 percent power when RU-141 stopped communicating with.the mini computer and experienced a microprocessor lockup (monitor will not count).Since RU-141 supplies sample flow to RU-142, the malfunction of RU<<141 caused RU-142 to be declared inoperable.

Troubleshooting was conducted in an attempt to reset the Central Processing Unit (CPU)to remove the monitor from the lockup condition.

The CPU board was removed and inspected for wear.No evidence of oxidation or excessive wear on the edge connectors was found.A new CPU board was installed and the lockup cleared.The CPU board will be examined in an effort to determine the cause of the malfunction.

The monitor was then connected to the test equipment to perform the quarterly functional test.During the test, the monitor did not pass the low flow equipment fail step indicating a leak in the piping connections.

Troubleshooting revealed minor air leakage between the flow instrument and the monitor inlet piping.The root cause of the air leakage was found to be a galled swagelock"T" connector.

As an immediate corrective action, the"-T" was replaced.Upon completion of the work order and appropriate surveillance test, RU-141 and 142 were restored to a operable status on July 1, 1987 at 1000 MST.The monitor was out of service for 8 days, 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> and 17 minutes.