United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #:  9704010450

                                        150 Lincoln Avenue

                                        Glove City, PA 16127-1898

                                        Tel 412 458 8000

                                        Fax 412 458 3574



COOPER                                  Cooper Bessemer

ENERGY SERVICES                         Enterprise [Trademark]

                                        En-Tronic [Registered Trademark]

                                        Penn [Trademark]

March 25, 1997                          Superior

Our Ref: QCG-10373

Document Control Desk

U.S.  Nuclear Regulatory Commission

Washington, D.C.  20555

Subject:  Commonwealth Edison Company, Zion Station, EDG

          Piston and Liner 10 CFR 21 Interim Report

Dear Sir:

The purpose of this letter is to provide initial notification and interim

report of a 10 CFR 21 evaluation associated with the Cooper-Bessemer KSV

Emergency Diesel Generators installed at Commonwealth Edison (CECo) Zion


On January 27, 1997 CECo identified a significant drop in crankcase lube

oil level.  Subsequent investigation revealed that a crack had developed

in the cylinder liner wall allowing jacket water to enter the combustion

chamber.  Jacket water in the combustion chamber is incompressible and

caused a hydraulic lock which resulted in a fracture in an area of the

piston crown, relieving the hydraulic lock.  Upon review of the failed

piston it was noted that the piston crown thickness in the area of

failure was below drawing specifications.

While the EDG continued to operate, the potential long term effect of the

above could be dilution of the crankcase oil with jacket water,

accompanied by a reduction in lubrication, ultimately resulting in

seizure of critical assemblies.

This event resulted in two distinct investigations, namely, the liner

failure causing the event and the piston crown thickness.  Each is

discussed below.

KSV Power Cylinder Liner

Cooper-Bessemer part number G18-9-12A#3 (safety-related) and G18-9-12A#2

(commercial, non-safety related).

Page 2

March 25, 1997


This is the only known failure of subject liner.  Evaluation activities

include sectioning of the liner, metallurgical analysis and finite

element analysis.  CECo has taken the primary role in this investigation,

assisted by Cooper-Bessemer.  Initial analysis has determined acceptable

stress levels.  Additional analysis is being conducted based on review of

the initial analysis by Cooper-Bessemer/CECo.

This liner design is only in use on "early" KSV engines in use at

Commonwealth Edison Company's Zion Station and Nebraska Public Power

District's Cooper Nuclear Station.  "Later" vintage KSV engines utilize

liners of different design and are not affected by this evaluation.

An improved design has been developed by Cooper-Bessemer which, in

essence, retrofits the "earlier" engines to the "later" design.  (New

part number KSV-9-3F#1).  Use of this liner as a replacement will be

recommended and is not dependent on the outcome of this evaluation.  It

is expected that this evaluation will be completed before May 28, 1997.

KSV Power Piston

Cooper-Bessemer part number KSV-5-A, KSV-5-A#1, KSV-5-3A#1 (commercial,

nonsafety) and KSV-5-A#2, KSV-5-2A, KSV-5-2A#1 (safety-related).

Failure of this piston was a direct result of the liner failure.  No

other such failure has been documented.  It has been determined that the

subject piston crown thickness at the point of failure was below drawing

requirements.  Investigation has determined that the pattern for the

piston casting was incorrect.  Preliminary stress analysis indicates that

stresses are relatively low in this area even for crown thickness

considerably below the drawing requirements.  Any piston operated for 600

hours or greater has experienced 10 X 10**6 stress cycles and thus is

unlikely to fail under normal loading.

Finite element analysis is being conducted by Cooper-Bessemer to

determine acceptable minimum thicknesses for the piston crown section.

This evaluation could affect the following KSV users:

Arizona Public Service- Palo Verde

Commonwealth Edison - Braidwood

Commonwealth Edison - Byron

Commonwealth Edison - Zion

Entergy Operations - Waterford III

Houston Lighting and Power - STP

Nebraska Public Power District - Cooper Nuclear Station

Niagara Mohawk - NMP2

Pennsylvania Power and Light - SSES

Page 3

March 25, 1997


It is expected that this evaluation will be completed before May 28,


Please contact Andrew Steffan at 412-458-3455 or John Horne at 412-458-

3543, if you have any questions.



R.  M.  Cote

Vice President and General Manager


cc:  D.  T.  Blizzard - CES/GC

     J.  M.  Horne - CES/GC

     T.  W.  Kearns - CES/GC

     W.  H.  A.  Lambert

     A.  P.  Steffan - CES/GC

     File: K5fa40

Page 4

March 25, 1997

OCG- 10373

Copies to:

Mr.  Walter Haass                  Mr.  Doug Mullen

U.S.  Nuclear Regulatory           Nebraska Public Power District

  Commission                       Cooper Nuclear Station

One White Flint North              P.  O.  Box 98

Washington, DC 20555               Brownville, Nebraska 68321

Houston Lighting and Power Co.     Mr.  Terry O'Brien

South Texas Project Electric       Commonwealth Edison Co.

P.  O.  Box 289                    1400 Opus Place

Wadsworth, TX 77483                Downers Grove, IL 60515

Attn: General Manager

      Nuclear Assurance &          Mr.  David Zink

        Licensing                  Niagara Mohawk Power Corp.

                                   Nine Mile Road - Unit 2

Mr.  James Kenny                   P.  O.  Box 63

Licensing Group Supervisor         Lycoming, NY 13093

Pennsylvania Power and Light

Two North Ninth Street Annex 6 1   Ms.  Kathleen Russo

Allentown, PA 18101                Niagara Mohawk Power Corp.

                                   Nine Mile Road - Unit 2

Mr.  Matthew Heidorn               P.  O.  Box 63

Pennsylvania Power and Light       Lycoming, NY 13093

Susquehanna Steam Electric Station

P.  O.  Box 467                    Arizona Public Service

Berwick, PA 18603                  P.  O.  Box 52034 Mail Station 6325

                                   Phoenix, AZ 85072-2034

Mr.  Terence Banno                   Attn: Department Leader

Licensing Group ALPHA 6 1                  Nuclear Materials Management

Pennsylvania Power and Light

2 North Ninth Street               Ms.  Angela Krainik

Allentown, PA 18101                Manager, Nuclear Regulatory Affairs

                                   Arizona Public Service

Mr.  David Baran                   P.  O.  Box 52034 Mail Station 7636

Commonwealth Edison Co.            Phoenix, AZ 85072-2034

Byron Nuclear Power Station

4450 North German Church Rd.       Mr.  Terry Vandevoort

Byron, IL 61010                    Commonwealth Edison

                                   Zion Generating Station

Mr.  Michael Kneble                101 Shiloh Blvd.

Energy Associates                  Zion, IL 60099

Louisiana Power and Light

Waterford 3 SES                    Mr.  Arthur G.  Killinger

Highway 18                         MPR Associates, Inc.

Taft, LA 70006                     320 King Street

                                   Alexandria, VA 22314-3238

Mr.  Dave Gustafson

Commonwealth Edison Co.

Braidwood Nuclear Power Station

Tech Staff Electrical Group

Route 1, Box 84

Braceville, IL 60407


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