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 li

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FACIL: STN-50-529 Palo Verde Nuclear Station> Unit 2> Arizona Pub 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 COPIES I REC P.I ENT COP IES ID CODE/NANE LTTR ENCL ID CODE/MANE LTTR ENCL PD5 LA 1 0 PD5 PD 1 LICITRA E 1 DAVISR N 1 1 INTERNAL: ACRS 2 2 AEOD 1 1 DEDRO 1 ENF LIEBERNAN 1 NRR ROE M. L MRR/ADT 1 NRR/DOEA DIR 1 1 NRR/DREP/EPB 1 1 NRR/DREP/RPB 2 2 NRR/DR IS DIR 1 1 R/P ILRB 1 1 OGC/HDS1 1 1 REQ F 1 RES SPEISi T 1 1 RG 5 FILE 01 1 EXTERNAL: LPDR 1 1 NRC PDR NSIC 1 NOTES: 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 (all w/a)

E. E. Van Brunt, Jr.

R. P. Zimmerman R. C. Sorenson E. A. Licitra A. C. Gehr wQ INPO Records Center I ~

I f~l 4J g IW oC CD CP 87P42 1P 121 '870330 P PPP5<EP PDR AD<C~

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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.