ML20210L130

Supplemental Special Rept 1-SR-85-035:on 851224,containment high-range Radiation Monitor RU-149 Declared Inoperable Due to Spurious High & Alert Radiation Alarms.Caused by Low Resistance in Radiation Monitoring Unit Cable

ML20210L130
Person / Time
Site:	Palo Verde
Issue date:	04/18/1986
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
1-SR-85-035, 1-SR-85-35, ANPP-36294-EEVB, NUDOCS 8604290190
Download: ML20210L130 (2)

Text

_

RfCGVED 1.R C Arizona Nuclear Power Projecti A"!? 2 I F:1 1: 34 P o BOX 52034

• PHOENIX. ARtIONA 85072-2034 April 187Gl986'l4 ANPP-36294-EEVB/0AL/98.05 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 (PVNGS)

Unit 1 Docket No - STN 50-528 (License NPF-41)

Supplemental Special Report - Radiation Monitoring Unit Not Restored to OPERABLE Status Within 72 Hours File: 86-020-404

Dear Mr. Martin:

Attached please find a Supplemental Special Report (1-SR-85-035) prepared and submitted pursuant to Technical Specification 3.3.3.1 and 6.9.2. This report provides updated information on a radiation monitoring unit not restored to OPERABLE status within 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 me.

Very truly yours, 4 tu 1 E. E. Van Brunt , Jr.

Executive Vice President Project Director EEVB/DAL/ dim Attachment ec: R. P. Zimmerman (all w/a)

A. L. Hon E. A. Licitra A. C. Gehr INPO Records Center 8604290190 860418 PDR ADOCK 05000528 S PDR tli m-o /

_ _-- _----- J

a Attachment to ANPP-36264 PALO VERDE NUCLEAR GENERATING STATION UNIT 1 Supplement to Special Report No.1-SR-85-035 RADIATION MONITORING UNIT NOT RESTORED TO OPERABLE STATUS WITHIN 72 HOURS Docket No. STN 50-528 License No. NPF-41 This supplement to Special Report No.1-SR-85-035 provides updated information on the event of December,1985, in which Radiation Monitoring Unit RU-149 was declared inoperable and subsequently exceeded Action Statement 27 of Palo Verde Unit 1 Technical Specification, Table 3.3-6.

The Containment High Range Radiation Monitor RU-149 was declared inoperable on December 24, 1985, due to spurious high and alert radiation alarms, and coincident spurious detector failure alarms. A work authorizing document was issued to troubleshoot the cause of the alarms and to repair the radiation monitor as appropriate. At 1430, on December 27, 1985, the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Action Statement for operability of the monitor was exceeded.

RU-149 is used only for post accident containment high range radiation monitoring. In the event RU-149 is inoperable, Energency Plan Implementing Procedure 14A provides for using RU-158B&C, RU-37, and RU-38 for post accident containment high range radiation monitoring.

The root cause of this event is believed to be intermittent low resistance in the radiation monitoring unit detector cable inside containment. The corrective action to be taken is repair or replacement of the detector cable.

This action was originally scheduled to be completed by February 1, 1986.

This action was rescheduled for the March outage due to ALARA considerations (the time required to erect scaffolding and complete repair or replacement of the cable was estimated to be two weeks). The radiation monitor is expected to be returned to operable status prior to resumption of power operation.