ML20044H076

Special Rept 93-001:on 930504,trip Signal Occurred During Performance of Monthly Functional Test for Standby DG 11. Caused by Inadequate Work Instructions.Surveillance Procedure Will Be Revised to Address Probe Magnetic Bars

ML20044H076
Person / Time
Site:	Grand Gulf
Issue date:	06/02/1993
From:	Hutchinson C ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
93-001, 93-1, GNRO-93-00067, GNRO-93-67, NUDOCS 9306070356
Download: ML20044H076 (2)

Text

a.u -

1 9

ea ""=.

- g{gp9Y Entorey Oporations,Inc.

eo emse

'i Onerations E

wwm =

tanc t.m June 2, 1993 U.S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Special Report 93-001 Invalid Failurt Jf Emergency Diesel Generator 11 Due to High Vibration Signal GNRO-93/00067 Gentlemen:

On May 04, 1993, during the performance of monthly Functional Test-06-OP-1P75-M-0001 for Standby Diesel Generator 11 (SDG), a trip occurred due to a high vibration signal.

The current surveillance procedure requires that vibration readings be taken with an IRD 350-Vibration Meter after the SDG has run loaded for 2 one hour. In order to acquire vibration data for'the turbocharger, the magnetic based probe has to be placed horizontally on the turbocharger of the operating SDG. While taking vibration data, the portable vibration probe dislodged from its horizontal position and fell onto a permanent vibration switch. The impact of the falling probe generated a high vibration signal which tripped the SDG.

The cause of this trip is attributed to inadequate work instructions. The procedure which was in place to give directions on the use of the vibration probe during SDG operation did not address the orientation (horizontal / vertical) of the probe's magnetic bars.

There was not a mis-operation of the vibration probe during the performance of the surveillance. The orientation of the probe's magnetic bars will not influence the vibration data being collected. If mounted horizontally, the weight of the probe can

' overcome the strength of horizontally aligned bars. Aligning the bars vertically while the probe is mounted horizontally will lower the potential of the probe dislodging from its required position.

9306070355 930602 PDR~ ADOCK

/ O S 05000416 PDR-l

9 June 2*, 1993 GNRO-93/00067 '

Page 2 of 3 i

The surveillance procedure will be evaluated and revised to address the orientation of the probe's magnetic bars during this evolution.

In Surveillance Procedure 06-OP-1P75-M-0001, vibration data is required to be taken after completion of a successful surveillance run of one hour at a load of 50 percent or greater. However, the data is not required to meet TS OPERABILITY requirements. The vibration trip is bypassed in an emergency condition, therefore this is considered an invalid failure.

Yours truly, ,

l C. R. Hutchinson i Vice President, Operations GGNS CRH/RR/

cc: Mr. R. H. Bernhard .

Mr. H. W. Keiser l Mr. R. B. McGehee Mr. N. S. Reynolds Mr. H. L. Thomas Mr. Stewart D. Ebneter Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta St., N.W., Suite 2900 2

Atlanta, Georgia 30323 Mr. P. W. O'Connor (w/2)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C. 20555 i l

__ _ _ _ ,