ML17300A756

Special Rept 2-SR-87-006:on 870309,radiation Monitor RU-139B Continuously Alarmed Due to Erroneous High Radiation Levels. Caused by Broken Wire in Microcomputer Preamplifier. Preamplifier Replaced & Root Cause of Failure Initiated

ML17300A756
Person / Time
Site:	Palo Verde
Issue date:	03/30/1987
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
192-00174-JGH-T, 192-174-JGH-T, 2-SR-87-006, 2-SR-87-6, NUDOCS 8704210121
Download: ML17300A756 (3)

Text

REGULATOR NFORNATION DISTRIBUTION S EN (R IDS)I." ACCESSION NBR: 8704210121 DOC.DATE: 87/03/30 NOTARIZED:

NO DOCKET 0 FACIL: STN-50-529 Palo Verde Nuclear Station>Unit 2>Arizona Pub li 05000529 AUTH.NANE AUTHOR AFFILIATION HAYNES>J.G.Arizona Nuclear Pouer Prospect (formerly Ari zona Public Serv RECIP.NAME RECIPIENT AFFILIATION NARTINi J.B.Region 5>Office of Director SUB JECT: Special Rept 2-SR-87-006:

on 870309.radiation monitor RU-139B continuously alarmed due+o erroneous high radiation levels.Caused bg broken wire in microcomputer preamplifier.

Preamplifier replaced h roo+cause of failure initiated.

DISTRISUTION CODE: IEOID COPIES RECEIVED: LTR ENCL SIZE: TITLE: General<50 Dkt)-Insp Rept/Notice of Vio ation R sponse NOTES: Standard i z ed plant.N.Davis>NRR: iCg.05000529 RECIPIENT ID CODE/NANE PD5 LA LICITRA E COPIES LTTR ENCL 1 0 1 REC I P.I ENT ID CODE/MANE PD5 PD DAVISR N COP IES LTTR ENCL 1 1 1 INTERNAL: ACRS DEDRO NRR ROE M.L NRR/DOEA DIR NRR/DREP/RPB R/P ILRB REQ F RG 5 FILE 01 EXTERNAL: LPDR NSIC NOTES: 2 2 1 1 1 2 2 1 1 1 1 1 1 1 1 1 AEOD ENF LIEBERNAN MRR/ADT NRR/DREP/EPB NRR/DR IS DIR OGC/HDS1 RES SPEISi T NRC PDR 1 1 1 1 1 1 1 1 1 1 1 1 , TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 24 Arizona Nuclear Power Project P.o.8OX 52034~PHOENIX.ARIZONA 85072-2034 192-00174-JGH/TRB/ESP March 30, 1987 Mr.John B.Martin, Regional'Administrator Office of Inspection and Enforcement U.S.Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368

Subject:

Palo Verde Nuclear Generating Station Unit 2 Docket No.STN 50-529 (License NPF-51)Special Report 2-SR-87-006 File: 87-020-404

Dear Mr.Martin:

Attached please find a Special Report 2-SR-87-006 prepared and submitted pursuant to Technical Specifications 3.3.3.1 and 6.9.2.This report discusses a Radiation Monitoring Unit Inoperable 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 Tom Bradish, Complianc'e Supervisor at (602)932-5300, Ext.6936.Very truly yours, tl4N~J.G.Haynes Vice President Nuclear Production JGH/TRB/ESP/cld Attachment cc: 0.M.DeMichele E.E.Van Brunt, Jr.R.P.Zimmerman R.C.Sorenson E.A.Licitra A.C.Gehr INPO Records Center (all w/a)I~I 4J CP wQ f~l g IW oC CD 87P42<C~P PPP5<EP 1P 121'870330 PDR AD S PALO VERDE NUCLEAR GENERATING STATION Radiation Monitor Inoperable for Greater Than 72 Hours License No.NPF-51 Docket No.STN 50-529 Special Report No.2-SR-87-006 This Special Report is being submitted pursuant to Technical Specification (T.S.)3.3.3.1 ACTION 27-3 and T.S.6.9.2 to report an event in which a main steam line monitor (RU-139B)was 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 0940 MST on March 12, 1987.Pursuant to T.S.3.3.3.1 ACTION 27-1 the preplanned alternate program was initiated to monitor the main steam system.At approximately 0940 MST on March 9, 1987, Palo Verde Unit 2 was in Mode 3 (HOT STANDBY)when RU-139B began alarming continuously due to erroneous high radiation levels.Radiation Monitors RU-139A and RU-139B monitor the steam generator 1 main steam lines for activity.Since RU-139A was functioning properly it was concluded that the high radiation levels indicated by RU-139B were erroneous.

Troubleshooting conducted under an authorized work document revealed that a preamplifier in the micro computer had a broken wire.As corrective action, the preamplifier was replaced.The cause of the broken wire is indeterminate.

A root cause of failure request has been initiated and will address the potential of similar cases in other monitors enco'mpassing all three units.To return RU-139B to service, Quarterly Functional Test (36ST-9SQ04) was successfully performed.

The monitor was declared operable at 0909 on March 13, 1987.The monitor was unavailable for 3 days, 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> and 36 minutes.