United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9601220338

Commonwealth Edison Company

Byron Generating Station

4450 North German Church Road

Byron, IL 64010-9794

Tel 815-254-5441

January 18, 1996                                                    ComEd

LTR:      BYRON 96-0016

FILE:     2.01-0703

U.  S.  Nuclear Regulatory Commission

Washington, DC 20555

Attention: Document Control Desk

Subject:  Byron Station Units 1 and 2

          Braidwood Station Units 1 and 2

          10 CFR Part 21 Notification

          Improper Material in Motor Operated Valve Motor Pinion Gear

          NCR Dockets 50-454 and 50-455

          NCR Dockets 59-456 and 50-457


This notification is submitted in accordance with the requirements of 10

CFR Part 21, Section 21.21(b), 21.3 a(3), and 21.3 d(4).

Identification of Facilities and Components

Byron Nuclear Generating Station Units 1 and 2

Braidwood Nuclear Generating Station Units 1 and 2

Motor Pinion Gears used in Motor Operated Valves (MOVs) procured from

Westinghouse Electric Corporation and supplied to Westinghouse by

Limitorque Corporation.

Actuator Size: SB-0

Motor: 25 Ft.-lb. 3600 RPM

Motor Pinion: 34 tooth part #60-415-0100-1

Identification of Component Manufacturer/Supplier

Limitorque Corporation             BYRON NUCLEAR POWER STATION #pages

5114 Woodall Road                  To:                 From:

P.O. Box 11318                     Co.                 Co.

Lynchburg, Virginia 24506-1318     Dept.               Phone #

                                   Fax #               Fax #

Byron Ltr. 96-0016

Page 2

January 18, 1996

Nature of Defect

The defect is related to the failure of a motor pinion gear at Byron

Station.  On 10/25/95, the 1CV8105 motor operated valve (MOV) at Byron

Station failed mid-stroke when it was being closed during normal plant

operations.  Subsequent troubleshooting indicated that the failure was

due to a sheared motor pinion gear.  Material analysis of the failed

motor pinion gear determined that the gear was made of an improper

material.  The material used was 11B44 versus the 4140, 4320, or 86L20

material that should have been used for this size operator.  AISI 11B44

material is a free-machining, re-sulferized, boron-bearing carbide steel.

Based on the results of the material analysis, it appears as if the

failed motor pinion gear was machined from cast stock.  The motor pinion

gear failure was attributed to the poor mechanical properties of the part

and the inability of the gear to sustain service loads.  The use of the

improper material in the motor pinion gear directly led to the failure of

the 1CV8105 valve to operate.

Time of Discovery

The failure of the 1CV8105 valve occurred on 10/25/95.  ComEd determined

that the failure was a potential defect subject to the provisions of

10CFR21 on 11/21/95.  Final determination that the defect was reportable

per 10CFR21 was made on 1/12/96.

Number and Location of All Defective Components:

The only known defective motor pinion gear was identified in the 1CV8105

valve at Byron Station.  The 1CV8105 valve at Byron Station was one (1)

of 12 MOVs that were purchased as a group from Westinghouse Electric

Corporation for ComEd's Byron and Braidwood Stations (6 MOVs for each

station).  The actuators/motors for these twelve (12) valves were

purchased from Limitorque Corporation by Westinghouse and supplied to


Corrective Actions:

ComEd initiated replacement and inspection activities for the potentially

impacted population of MOVs at Byron and Braidwood Stations including

testing of 14 spare replacement motor pinion gears in ComEd Stores of

that particular gear size.  To date, 20 of 21 gears tested have been

determined to be of the correct material.  The only identified use of the

improper material was in the motor pinion gear that was removed from the

1CV8105 valve at Byron Station. Two (2) MOVs at Braidwood Station from

the suspect Purchase order were subsequently determined to have different

gear ratios and not be impacted by this defect.  From the original lot of

MOVs purchased together, two (2) MOVs at Byron Station and one (1) MOV at

Braidwood Station remain to have their motor pinion gears replaced and

inspected.  These MOVs arc on operating units at the respective stations.

Byron Ltr. 96-0016

Page 3

January 18, 1996

The inspection and replacement activities will take place prior to or

during the next outage on each unit.  These actions are being tracked by

the station's respective corrective action programs.

At this time, based on conversations with the vendor, Limitorque

Corporation, and the positive inspection results of other potentially

impacted components, ComEd believes that the presence of the defective

material in the 1CV8105 valve at Byron Station was an isolated incident.

Beyond the inspection of the three (3) remaining motor pinion gears at

Byron and Braidwood Stations, no further actions are anticipated.

However, it is ComEd's understanding that the vendor is currently

evaluating this defect for any generic applicability and will notify

licensees, as appropriate.

10 CPR 21 Evaluation

The 1CV8105 valve at Byron Station is a safety related valve in the

Chemical and Volume Control System (CVCS) that is used as an isolation

valve during normal charging activities.  The specific failure of the

1CV8105 valve on 10/25/95 did not lead to an incident of significant

magnitude.  However, there was a potential for a more significant event.

There is a redundant valve (1CV8106) in series with the 1CV8105 valve

that is capable of performing the same design function. However, the

presence of the improper material in the 1CV8105 did represent a

reduction in the inherent design margin of the system.

Therefore, ComEd has determined that the procurement of the motor pinion

gear with the improper material does constitute a defect per the

requirements of 10CFR21 and is providing this notification to the NRC.


Byron Ltr 96-0016

Page 4

January 18, 1996


Questions pertaining to this notification should be addressed to:

Bradley J.  Adams

Site Engineering

ComEd Byron Station

4450 N.  German Church Road

Byron, Illinois 61010

(815) 234-5441 x2979


K.  L.  Graesser

Site Vice President

Byron Nuclear Station


cc:  H.  Miller, Regional Administrator-RIII

     H.  Peterson, Senior Resident Inspector (Byron)

     C.  Phillips, Senior Resident Inspector (Braidwood)

     G.  Dick - NRR

     R.  Assa - NRR

     Office of Nuclear Facility Safety - IDNS



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