ML20212H142

Interim Part 21 Rept SSH 98-002 Re EG-B Unit That Was Sent to Power Control Svcs for Determination of Instability & Refurbishment of a Dg.Cause of Speed Oscillations Unknown. Completed Hot Bore Checks on Power Case

ML20212H142
Person / Time
Site:	Summer
Issue date:	03/02/1998
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-98 SSH-98-002, SSH-98-2, NUDOCS 9803110133
Download: ML20212H142 (2)

Text

I h'

Carolina Electric & Gas Company J.

s *(.,.

Jenkinsville. SC 29065 Nuclear Operations I (803) 345-4344 j SCE8tG March 02,1998 jm% j RC-98-0045 i i

Document Controi Desk U. S. Nuclear Regulatory Commission {

Washington, DC 20355 i Gentlemen:

Subject:

VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 INTERIM REPORT PURSUANT TO 10 CFR PART 21 (SSH 98 002)

This letter describes the preliminary investigation into a potential 10 CFR Part 21 reportable issue regarding the "A" Diesel Generator EG-B for the Virgil C. Summer Nuclear Station. This interim report is submitted pursuant to the requirements of 10 CFR 21.21(a)(2).

1 The Woodward goverrior hydraulic actuator (EG-B) unit was sont to Power Control Services of Engine Systems Inc. for an as-found evaluation and refurbishment following the speed oscillations which occurred during surveillance testing on 12/30/97. From  ;

the initial evaluation of this unit, it was determined that there were several nicks on the lower land area of tne main relay plunger, it was' initially believed that this problem could have accounted for the speed oscillations seen during the event. However, follow-up' investigations, including replacement of the suspect part have failed to correct the instability in this unit. Therefore, an interim report for Part 21 reporting is necessary to allow additional troubleshooting and cause determination for this EG-B.

The vendor anticipates that the problem with the EG-B will be shortly identified and a response should be provided to VCSNS by 3/31/98. A final report on the Part 21 evaluation will be submitted within thirty days of receipt of the vendor's information. /g Speed oscillations occurred on the "A" diesel generator after opening the DG output j breaker during surveillance testing (STTS#9721373) on 12/30/97. After extensive jpJ troubleshooting, it was determined that these speed oscillations were due to a problem with the Woodward governor hydraulic actuator .(EG-B) unit. The EG-B unit was ,

replaced and the oscillations disappeared.  ;

i The EG-B unit (Serial No. 1380933) was sent to Power Control Services (Woodward representative) for a determination of the cause of the instability and for refurbishment.

After disassembly, several nicks were found on the lower land area of the main relay

' -r. It was initially thought that this could have caused the instability. This  ;

cv..ppnent is s,ubjected to pressures in excess of 500 PSIG and must control porting of

,,.1 v v ~ ~ .

NUCLEAR EXCELLENCE - A SUMMER TRADITION!

, g lll&

9903110133 990302 5 DR ADOCK 0500

hydraulic fluid during governor operation. The vendor also recommended that

,additianal research be performed to: 1) perform hot bore dimensional checks on the sub-governor power case, and 2) review the previous repair records when the unit had been refurbished 12 years earlier prior to being stored in the VCSNS warehouse.

Presently, the hot bore checks have been completed on the power case with no problems identified. Also, the EG-B was reassembled using a new power case with the l old relay plunger and instability was still observed. Additionally, the EG-B has been L disassembled. and reassembled several times with a new power case and relay l plunger, but the unit still exhibits instability. Also, several other parts including i bushings and seals have been replaced, but instability has not been corrected. The l effort is continuing to identify the cause of this problem.

l Previous repair records have still not been located. This is attributed to the 1985 repair being performed at the Fort Collins, Colorado facility (nuclear units are now repaired at the Rocky Mount, North Carolina facility) and to computer changes which occurred at Woodward in the early 1990s. Retrieval of these records is still being pursued.

! Due to these ongoing efforts the cause of the speed oscillations has not been l determined and therefore, an interim 10 CFR Part 21 report is required.

l L Should you have any questions, please call Mr. Michael J. Zaccone at (803) 345-4328.

i

Very truly yours, P 0 $& na qar Gary J. Taylor GJT/mjz c

J. L. Skolds D. L. Abstance W. F. Conway R. J. Waselus l R. R. Mahan (w/o attachment) R. L. Osbome l R. J. White G. A. Robertson L.A.Reyes J. B. Knotts Jr.

L. M. Padovan NRC Resident inspector i R. B. Clary INPO Records Center l l

M. F. Miltner Marsh & McLennan A.R.Koon NSRC  ;

G. E. Williams RTS (SSH 980002) I T. L. Matlosz Files (818.18)

B. C. Williams DMS (RC-98-0045) l P. Ledbetter l l

I