ML20107G966

Special Rept:On 841229,seismic Monitoring Sys Power Supply Failed.Cause Unstated.On 850103,surveillance Test for Two Installed Power Supplies Failed.On 850128,output Reversal Experienced During Installation of New Power Supply

ML20107G966
Person / Time
Site:	Palo Verde
Issue date:	02/08/1985
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
ANPP-31897-EEVB, NUDOCS 8502270008
Download: ML20107G966 (3)

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Arizona Public Service Company . _ , .

A P- 1897- V WFQ February 8, 1985 q' EG',0N'W 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 Special Report - Inoperable Seismic Monitors Docket No. STN 50-528(License No. NPF-34)

File: 85-056-026; G.1.01.10

Dear Mr. Martin:

Attached please find a Special Report prepared and submitted pursuant to Specifications 3.3.3.3 and 6.9.2 of Appendix A (Technical Specifications) to the Palo Verde Nuclear Generating Station, Unit No. 1 Operating License.

This report discusses inoperable seismic monitors.

If you have any questions or concerns, please contact me.

Very truly yours, bb CL E. E. Van Brunt, Jr.

APS Vice President Nuclear Production ANPP Project Director i

EEVB/GEC/mb Attachment I cc: A. C. Gent i R. P. Zimmerman E. A. Licitra INPO 8502270008 850200 PDR ADOCK 0500 S &

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ATTACHMENT REPORT ON SEISMIC MONITORING SYSTEM Cause: The Seismic Monitoring System power supply experienced a total failure of both +12VDC and -12VDC power. Both power supplies are essential to system operation. No power supply spares were stored on site or by the vendor because the power supply is obsolete.

A new model power supply was procured. During installation a power supply output reversal (due to a procedure error) to the Lower Digital Cassette Accelerograph caused the failure of three circuit cards, of which only one could be replaced from spare parts. (See also Chronological History section of this report).

Plans for System Restoration: The two remaining failed circuit cards have been returned to the vendor for repair. There is no firm forecast to complete the repairs at this time, but it is expected to take two to three weeks.

The repairs will be expedited to the fullest extent possible. Additionally, two of each type of cards are being purchased as spares.

Present System Status:

The following instruments are not in operation:

1. XT-4, Triaxial Accelerometer, Control Building /XR-4, Digital Cassette Recorder, Control Room.

2. -XT-5, Triaxial Accelerometer, Auxiliary Building /XR-5, Digital Cassette Recorder, Control Room.

3. XT-6, Triaxial Accelerometer, free field (outside of Turbine Building)/XR-6, Digital Cassette Recorder, Control Room.

The remainder of the Seismic Monitoring System is in operation.

Chronological History:

Date: Event:

12/29/84 The Seismic Monitoring System power supply experienced a total failure. No spares were on site nor were they obtainable from the vendor.

1/1/85 Operating license received on site - limiting condition for operation entered.

1/3/85 Two temporary power supplies were installed to supply both +12VDC and -12VDC, necessary for system operation.

The surveillance test failed and the If0 was still in effect.

A new model power supply, that is compatible with the system, was ordered from the vendor (Terra Technology Corporation). Arrival was forecasted for 1/23/85.

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ATTACHMENT

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Date: Event:

1/9/85 A second power supply was ordered from the vendor for use as a spare.

1/25/85 'A new model power supply was received.

1/28/85 During installation of the new power supply, a wiring error caused +12VDC to be applied to the -12VDC bus of the Lower Digital Cassette Accelerograph (DCA).

This DCA houses circuits for three of-the six accelero-meters.

1/31/85 Troubleshooting revealed that three circuit cards failed.

One was replaced, however, spares were not available for the other two. The rest of the system, other than those instruments not currently operable, was placed back into operation.

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