ML20066C238

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Supplemental Special Rept:On 900712 & 17,diesel Generator 2A & 2B Invalid Failures Occurred During Operability Testing of Engine.Initially Reported on 900517 & 0620.Procedures, Addressing Paralleling of Generator,Will Be Revised
ML20066C238
Person / Time
Site: Catawba  Duke Energy icon.png
Issue date: 01/02/1991
From: Tuckman M
DUKE POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9101090383
Download: ML20066C238 (3)


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+;I OUKEPOWCR January 2, 1991 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C.

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Subject:

Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50 414 Special Report Supplememt

11. B. Tucker's letter to the Document Control Desk dated June 20, 1990 t.ransmitted a Special Report concerning invalid failures on Catawba Nucicar Station Unit 2 Diesel Generators 2A and 2B.

This report was submitted pursuant t.o Catawba Technical Speelfleations 6.9.2 and 4.8.1.1.3.

Attached is a supplement to the June 20, 1990 submittal.

Very truly yours, h, 3.

A M. S. Tuckman, Vice President Nuclear Operations CRid8/lcs Attachment xet Mr. S. D. Ebneter Regional Administrator, Region 11 U. S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. R. E. Martin Office of Nuclear Reactor Regulations U. S. Nuclear Regulatory Commission One White Flint North, Mail Stop 9113 Washington, D.C.

20555 Mr. W. T. Orders NRC Resident Inspector Catawba Nuclear Station Y

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SUPPLINEldT TO SPECIAL REPORTS DATED MAY 17. 1990 AND JUNE 20, 1990 CATAWBA NUCLEAR STATION J

DIESEL GENERATOR 2A 6 2B INVALID FAILURES DURING OPERABILITY TESTING OF ENGINE 1

i This is a supplement to the Special Reports submitted following 3 l

Invalid failures associated with a reverse power relay actuation on j

Diesel Generators (D/G) 2A and 2B (letters dated May 17, 1990 and June 20, 1990). A Special Testing Program was developed by the Transmission Department and Instrumentation and Electrical Section (IAE) to further evaluate the proper functioning of the components involved. This program checked the operation of the reverse power relay for D/G 2A and found it to be operating properly. Test equipment, was connected to appropriate circuite to monitor for conditions that could cause reverse power relay actuation. Testing was scheduled along with the break in runs following 2E003 maintenance for each engine.

During the runs, different sperators paralleled the engine several times to allow for evaluation of the techniques that each individual may have acquired.

D/G 2A was the first engine to be inspected during 2E0G3 outage.

During it s break-in runs on 7/12/90, Transmission and IAE monitored kW, kVAR, power factor, synchroscope operation, and the direction of phase angle on the reverse power relay.

Several different operators successfully paralleled the generator to the essential bus and the protective systems performed as designed.

On 7/17/90. the essential bus was ready to be swapped back irom its alternate souu a to its normal source.

The 2A D/G is used to maintain the loads on essential switch gear while the breaker is swapped back to its normal cubical. While D/G 2A was carryinr, t.he load on the essential switch gear, the load on the engine was 850 kW, i

800 kVARs with a power factor of.76 lagging. When the breaker was closed to the essential switch gears normal source, the load on the D/G dropped to less than zero which indicated a reverse power condition.

The phase angle meter connected across the reverse power relay confirmed the condition.

The operator attempted to reduce load further following the normal procedural practice of reducing D/G load to 200 kW.

Since the load was aircady at or below zero, this caused a reverse power relay actuation.

Based on this Special Testing / Evaluation of the D/G paralleling evolution by the Transmission Department and the IAE Section, all i

invalid f ailurcs that have occurred due to reverse power relay actuation can be directly attributed to Operator Error.

The Corrective actions taken, or to be taken, to reduce the potential i

for this type of invalid failure aret The NLO's have boon given additional training during Requal Segment on paralleling the D/G to the grid.

This Operational Proficiency training involved both classroom and walk through exerMses. The operators were refreshed on the generator and the effects of the controls for the generator and engine.

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in addition the layout of the controls may have been a contributing factor to the operator error. A Station Problem Report will be generated to request Design Engineering to perform a formal Iluman l

Engineering Design Review of the Diesel Generator and Engine Control l-Panels.

l Operations procedures that address paralleling the D/G will be revised i

to provide-the operator with additional information on the voltage to be maintained when paralleling the engine.

Presently the procedure says

" Adjust Voltage (" VOLTAGE CONTR0!.") to allow D/G voltage to be slightly l

highur than line voltage." This will be revised to provide a specific j

range within which the D/G voltage shall bc held above the line voltage, b

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