United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9808030076







                              150 Lincoln Avenue

                              Grove City, PA 16127-1898

                              Tel 412 458 8000

                              Fax 412 458 3574



                              Ajax [Registered Trademark]

                              Coberra [Registered Trademark]

COOPER                        Cooper-Bessemer [Registered Trademark]

ENERGY SERVICES               Enterprise [Trademark]

                              En-Tronic [Registered Trademark]

                              Penn [Trademark]

                              Superior [Registered Trademark



July 29, 1998



Our reference: QCG-10496 (K5fb69)



Document Control Desk

U.S.  Nuclear Regulatory Commission

Washington, D.C.  20555



Subject:  QCG 10483 (K5fa43)

          10 CFR Notification, Enterprise DSR-4 and DSRV-4 Emergency Diesel

          Generators



Dear Sir,



In accordance with the requirements of the Nuclear Regulatory Commission

Title 10, Chapter 1, Code of Federal Regulations, Part 21, Cooper Energy

Services (CES), a division of Cooper Cameron Corporation, provides a final

status report of the 10 CFR Part 21 evaluation associated with the 701

Digital Speed Control, Rev. G provided to Southern Nuclear Company's Plant

Vogtle and Texas Utilities' Comanche Peak.



An interim letter was sent on May 22, 1998 describing a 10 CFR Part 21

investigation concerning the use of revision level "G" Woodward 701

governing systems (Cooper Energy Services P/N 2-02G-110-001) supplied to

Southern Nuclear Company's Plant Vogtle and Texas Utilities' Comanche Peak

generating stations.  A problem arose when the originally supplied

revisions of the Woodward governor DSC (digital speed control) were removed

and replaced with a revision "G" DSC.  The revision "G" DSC output to the

governor actuator exhibited short-term instability when generator voltage

was adjusted remotely from the control room.  The revision "G" DSC operated

properly when in local operation from the diesel generator room.  As an

immediate corrective action, the revision "G" DSC's were removed, and the

originally supplied DSC's were put back into service and are operating

satisfactorily.



Investigations revealed that the revision "G" DSC's were more susceptible

to electromagnetic interference (EMI) induced by the long runs of cable to

and from the control room, specifically feeding back into the low voltage

output (terminal 5) of the DSC than were the revision "A" and "B" DSC's.

The short term instability was found during post installation testing and

setup as part of the design modification / post work testing process.

Subsequent testing verified that both the revision "B" and "G" DSC meet the

EMI / RFI (Radio Frequency Interference) design specifications, MIL

Standard 461 C, that the units were qualified to as per CES contractual

agreements with Comanche Peak and Plant Vogtle.  Based on the

aforementioned findings, it is judged that the subject anomaly is not

reportable from Cooper Cameron's basis under 10 CFR Part 21.  The revision

"G" design met all EMI/RFI design specifications, however the excess margin

was reduced to where specific plant conditions (as found during post

installation testing) exceeded tolerable EMI levels.



Page 2

July 29, 1998

REF: QCG-10496 (K5fb69)



Cooper Energy Services (CES) and Woodward in conjunction with Comanche Peak

personnel were able to recreate conditions similar to those in the field in

a laboratory environment producing the same governor output instability.

Plant Vogtle and Comanche Peak generating stations both have multi-

conductor cables from the Diesel room to the Control room with the

generator voltage raise / lower conductors in the same cable as the 701

speed raise / lower conductors.  These long runs of unshielded conductors

allowed EMI from the generator raise / lower conductors to be induced into

the 701 speed raise / lower conductors producing EMI levels greater than

what the 701 revision "G" DSC is qualified to.



None of the several hundred commercial 701 units utilize these long runs of

multi-conductor cabling and none of the several hundred commercial units in

operation have experienced this problem.  Three nuclear 701 revision "G"

units installed in Taiwan do not utilize the same multiconductor cable for

speed and voltage raise / lower conductors from the Diesel room to the

Control room and also do not experience this problem.



Different methods were developed to correct the problem with the most

viable option being the use of an EMI/RFI filter on terminal 5 of the DSC.

Testing at Woodward substantiates elimination of the 701 DSC output spikes

with the utilization of the EMI / RFI filter on terminal 5 of the DSC.  CES

is in the process of qualifying the filter for nuclear use and will

recommend its usage on all new 701 units.  CES also is providing the option

of two additional filters to be used on the DSC power input and the DSC

output to the governor actuator to enable the 701 Woodward governing system

to meet the new EPRI EMI / RFI guidelines (EPRI 102323-R1).



Anyone having any questions or concerns may contact Bob Boyles (724-458-

3446) or Terry Sintkowski (724-458-3433) at CES.



Affected Sites:



     Southern Nuclear Company, Plant Vogtle

     Texas Utilities, Commanche Peak Station

     STP Nuclear Operating Company (Houston Light and Power Co.)



Sincerely,



COOPER ENERGY SERVICES



Peter DeFronzo

General Manager



Copies to:



Mr.  Louis Ward, Southern Nuclear Company (Fax 205-992-7885)



Page 3

July 29, 1998

REF: QCG-10496 (K5fb-69)



Southern Nuclear Operating Company

Vogtle Project

P.O.  Box 1295

Birmingham, AL 35201

Attn: Mgr., Nuclear Engineering and Licensing



Mr.  Stephen Alexander

Nuclear Regulatory Commission

QA Vendor Insp.  & Maintenance Branch

One White Flint North

Mailstop 9A1

Washington, DC 20555



TU Electric Company

P.O.  Box 1002

Glen Rose, TX 76043

Attn: Group Vice President, Nuclear



STP Nuclear Operating Company

South Texas Project Electric

P.O.  Box 289

Wadsworth, TX 77483

Attn:     General Manager

          Nuclear Assurance and Licensing



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