Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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
Applicability
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
ComEd.
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.
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Byron Ltr 96-0016
Page 4
January 18, 1996
Contact
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
Sincerely,
K. L. Graesser
Site Vice President
Byron Nuclear Station
KLG/BA/rp
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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