Part 21 Report - 1998-152

 
 

ACCESSION #: 9803110133



               South Carolina Electric & Gas Company   Gary J. Taylor

               P.O. Box 88                             Vice President

               Jenkinsville, SC 29065                  Nuclear Operations

               (803) 345-4344

SCE&G

A SCANNA Company

                              March 02, 1998

                              RC-98-0045



Document Control Desk

U. S. Nuclear Regulatory Commission

Washington, DC 20555



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).



The Woodward governor hydraulic actuator (EG-B) unit was sent 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 the 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.



Speed oscillations occurred on the "A" diesel generator after opening the

DG output breaker during surveillance testing (STTS#9721373) on 12/30/97.

After extensive 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.



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 plunger.  It was initially

thought that this could have caused the instability.  This component is

subjected to pressures in excess of 500 PSIG and must control porting of



                NUCLEAR EXCELLENCE - A SUMMER TRADITION!



hydraulic fluid during governor operation.  The vendor also recommended

that additional 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 old relay plunger and instability was still observed.

Additionally, the EG-B has been disassembled and reassembled several

times with a new power case and relay plunger, but the unit still

exhibits instability.  Also, several other parts including bushings and

seals have been replaced, but instability has not been corrected.  The

effort is continuing to identify the cause of this problem.



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 determined and therefore, an interim 10 CFR Part 21 report is

required.



Should you have any questions, please call Mr. Michael J. Zaccone at

(803) 345-4328.



                              Very truly yours,



                              Gary J. Taylor



GJT/mjz



c:   J. L. Skolds                  D. L. Abstance

     W. F. Conway                  R. J. Waselus

     R. R. Mahan (w/o attachment)  R. L. Osborne

     R. J. White                   G. A. Robertson

     L. A. Reyes                   J. B. Knotts Jr.

     L. M. Padovan                 NRC Resident Inspector

     R. B. Clary                   INPO Records Center

     M. F. Miltner                   Marsh & McLennan

     A. R. Koon                    NSRC

     G. E. Williams                RTS (SSH 980002)

     T. L. Matlosz                 Files (818.18)

     B. C. Williams                DMS (RC-98-0045)

     P. Ledbetter



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