RBG-31433, Special Rept:On 890731,invalid Failure of Div III Diesel Generator Experienced During Surveillance Testing.Caused by Operator Error While Timing Generator Voltage,Per Reg Guide 1.108.Generator Declared Inoperable W/Controls Set

Special Rept:On 890731,invalid Failure of Div III Diesel Generator Experienced During Surveillance Testing.Caused by Operator Error While Timing Generator Voltage,Per Reg Guide 1.108.Generator Declared Inoperable W/Controls Set

ML20247F557
Person / Time
Site:	River Bend
Issue date:	08/30/1989
From:	Booker J GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-REGGD-01.108, RTR-REGGD-1.108 RBG-31433, NUDOCS 8909180212
Download: ML20247F557 (3)

Text

. , - - . _

r *4'

' GULF STATES UTILITIES COMPANY IUVER rdND SYAh0N POS1 OFDC.E BOX 22J ST F6ANCI5VtLLE, LDe5 /AA 70775 tJ;E A CODE S01 6%40M 346 BM1 August 30 ,1989 RBG- 31433 File Nos. G9.5, G9.25.1.4 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 Docket No. 50-458 Enclosed is Gulf States Utilities Company's Special Report concerning an invalid failure of the Division III diesel generator during surveillance testing at River Bend Station.

l This report is being submitted pursuant to River Bend Station Technical Specifications 4.8.1.1.3 and 6.9.2.

Sincerely, i e f. <

J. E. Booker l Manager-River Bend Oversight River Bend Nuclear Group JEB/ /h /TES/ch cc: U. S. N ear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 i

Arlington, TX 76011 l NRC Resident Inspector P.O. Box 1051 St. Francisville, LA 70775

/ l  ;

1 8909180212 890830 '

PDR S

ADOCK 05000458 )

PDC l 1

_ _ _ _ _ _ . I

I -

m l 4 L #

SPECIAL REPORT At 1014 on 7/31/89 an invalid failure was experienced on the Division III

! high pressure core spray diesel generator (DG) due to operator error while timing the DG voltage during a DG start for surveillance testing. This timing must 'oe performed to verify that DG starting parameters meet predetermined limits within time requirements of Technical Specification (TS) 4.8.1.1.2. The following information is provided in accordance with Regulatory Guide 1.108.

Diesel Generator Unit Designation and Number: Division III, IE22*EGS001 Investigation:

Surveillance Test Procedure (STP)-309-0203, " Division III Diesel Generator Operability Test", requires the use of digital stopwatches to verify starting parameters occur within TS limits for engine speed (RPM), generator frequency (Hz), and generator voltage. The generator voltage reached 3740 volts at 10.05 seconds following the DG stort signal. This time exceeded the maximum TS time limit of 10 seconds. The Division III DG was then declared inoperable in accordance with TS 3.8.1.1.

Investigation into the start determined that the required engine speed (882 RPM) was achieved in 9.54 seconds and generator frequency (58.8 Hz) was achieved in 9.68 seconds. These parameters were both within the TS time requirements of 10 seconds. Investigation also determined that the steady-state generator voltage (4160 volts) was achieved in 10.21 seconds and steady-state frequency (60 Hz) was achieved in 11.06 seconds. The TS requires these steady-state parameters be achieved within 13 seconds.

Therefore, time for these parameters were also acceptable.

A review of past Division III DG starts indicated that starting voltages had averaged 9.83 seconds. Discussions between Operations and Engineering personnel found no reason to question the validity of the measured start timing withoet additional data. Therefore, the STP was re-performed at 1354 with no modification to the engine. Timing for the starting generator voltage (9.83 seconds) as well as for the other parameters were acceptable.

GSU has therefore concluded that the unacceptable time recorded for the DG start at 1014 was due to an operator timing error. Therefore, in accordance with Regulatory Guide 1.108, paragraph C.2.d.2, this test has been determined to constitute an invalid failure.

Length of Time Unavailable:

The Operations Shift Supervisor took the conservative action by declaring the Division III DG inoperable. Even though the DG was declared inoperable, its controls remained set that it could have received a start signal. At all times the DG remained available to respond to an emergency start signal.

Page 1 of 2

.',.7'j,

• Current Surveillance Interval:- Division I Monthly Division II Monthly Division III Weekly Test Intervals Conforms to Technical Specification: Yes f Failures for'Div I: 0' Valid failures in the last 20 Valid Tests 1 Valid failures in the last 100 Valid Tests Failures for Div II: 0 Valid failures in the last 20 Valid Test.

4 Valid failures in all 87 Valid Tests Conducted Failures for Div III: 2 Valid failures in the last 20 Valid Tests 2 Valid failures in all 92 Valid Tests Conducted

' Number of Valid Failures in Last 100 Valid Tests of All Diesel Generators at River Bend Station: 2 Page 2 of 2

_ _ _ _ _ - _ _ - _ _ - .