Part 21 Report - 1998-261
ACCESSION #: 9803240135
1400 Opus Place
Downers Grove, IL 60515
ComEd
March 16, 1998
Document Control Desk
United States Nuclear Regulatory Commission
Washington, D.C. 20555-001
Subject: Dresden Nuclear Generating Station Units 2&3;
NRC Dockets: 50-237 and 50-249
LaSalle County Nuclear Generating Station Units 1 & 2
NRC Dockets: 50-373 and 50-374
Quad Cities Nuclear Generating Station Units 1 & 2
NRC Dockets: 50-254 and 50-265
10CFRPart 21 Notification
SBM Control Switch Binding
Reference: GE Nuclear Energy January 23, 1998 Transfer of Information
Pursuant to 10CFR Part 21.21(b) re: "Spring Return Binding
in GE Type SBM Control Switches"
Applicability
This notification is submitted in accordance with the requirements of
10CFR Part 21.
Identification of Facilities and Components
Dresden Nuclear Generating Station Units 2 and 3
LaSalle County Nuclear Generating Station Units 1 and 2
Quad Cities Nuclear Generating Station Units 1 and 2
GE Type SBM Control Switches with the spring return function manufactured
since March 1996. Applicable date codes: PL, RL, SL, TL, UL, VL, WL, XL,
YL, ZL, NM, OM, PM, RM, SM, UM, VM, WM, XM, YM, ZM, NN.
Identification of Component Manufacturer/Supplier
Manufactured by: GE Electrical Distribution and Control Power
Management
Malvern, Pennsylvania
as commercial grade items
g:\sbmp21.doc
A Unicom Company
Document Control Desk - 2- March 16, 1998
Dedicated by: GE-Nuclear Energy
175 Curtner Ave,
San Jose, California 95125
Nature of Defect
As described more fully in the referenced GE transfer of information
submittal in accordance with 10CFR Part 21.21(b), SBM switches identified
above are susceptible to binding which may prevent spring return to reset
(return to normal position). The cause of binding is attributed to
failure to account for "post mold cure" shrinkage in the design tolerance
of the clearance between the phenolic rear bearing support hole and the
bearing. This design error did not become apparent until the molds
experienced wear to the extent that resulting parts were at the extremes
of dimensional tolerances. The post mold cure is normal for the phenolic
material and has been shown to take place over a period up to two years
after molding is completed. Consequently switches which are constructed
from components that are within specification and function fully during
acceptance testing may exhibit sluggish return or binding up to two years
after assembly. This root cause is supported through GE examination of
failed switches which, in each instance, has found the bearing support
hole to be undersized (less than minimum inside diameter) and the bearing
at or near its maximum allowable diameter. GE testing has also confirmed
that switches with bearings that are at their nominal diameter will
function properly, even when the support hole is undersized, consequently
the failure is not seen in every switch.
Time of Discovery
Commonwealth Edison determined that the failure was a potential defect
subject to the provisions of 10CFR Part 21 on January 27, 1998, Final
determination that the defect was reportable per 10 CFR Part 21 was made
on March 16, 1998.
Number and Location of All Defective Components
Commonwealth Edison has determined that suspect SBM switches are not
installed at its Braidwood, Byron or Zion Nuclear Generating Stations.
Commonwealth Edison Nuclear Generating Stations which have the suspect
safety related spring return switches include Dresden, LaSalle County and
Quad Cities with two (2), two hundred forty six (246), and three (3)
switches installed respectively. LaSalle County Station is currently
experiencing binding in 21 of these switches.
Corrective Actions
Commonwealth Edison facilities having the suspect safety related SBM
switches have established Operability Determinations which demonstrate
affected systems remain operable while prompt corrective action is
pursued. Measures have been taken at Dresden and Quad Cities Stations,
which have only 2 and 3 switches susceptible to binding respectively, to
heighten operator awareness of the condition through placement of caution
cards on the affected switches, Additionally, these facilities have
initiated Action Requests to replace the switches with switches not
subject to the identified condition at the first available opportunity.
Both of the LaSalle County Station units are currently in extended
maintenance outages.
g:\sbmp21.doc
Document Control Desk - 3- March 16, 1998
LaSalle County Station has established operability by heightening
operator awareness through communication and is currently establishing
the scope of additional compensatory and corrective action plans to
demonstrate operability as applied to future plant operating conditions.
10CFR Part 21 Evaluation
In The course of evaluating the condition reported by GE in the
referenced transfer of information notice, Commonwealth Edison has
concluded that, in the absence of compensatory action, the reported
deviation substantially increases the likelihood of switch failure when
compared to a nominal base case switch failure rate without the reported
condition. Since the switches control the operation of various equipment
important to plant safety, this increase in failure rate without
compensatory action has been determined to constitute a defect
representing a substantial safety hazard per the requirements of 10CFR
Part 21 and is reportable to the NRC.
Contacts
Questions pertaining to this notification should be addressed to this
office or by contacting:
Robert N. Cascarano Jeffrey Nagel
Nuclear Engineering Services Technical Support & Parts Engineering
Design Basis Programs Central Testing & Materials Engineering
Facility
1400 Opus Place, Suite 300 555 Joliet Road
Downers Grove, Ill 60515 Bolingbrook, Ill 60446
(630) 663-7489 (630) 783-3150
Sincerely,
John B. Hosmer
Engineering Vice President
Nuclear Generation Group
Commonwealth Edison Company
cc: A. Bill Beach, Regional Administrator - Region III
Senior Resident Inspector, Dresden Station
Senior Resident Inspector, LaSalle County Station
Senior Resident Inspector, Quad Cities Station
NRR Project Manager, Dresden Station
NRR Project Manager, LaSalle County Station
NRR Project Manager, Quad Cities Station
Office of Nuclear Facility Safety - IDNS
Irene Johnson
DCD Licensing
g:\sbmp21.doc
Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 1
Page 2 of 2
10CFR PART 21 EVALUATION CHECKLIST
1. Engineering Part 21 File Number 98-01
2. Document Generated By General Electric
3. Date of Document 1/23/98
4. Document Identification Number(s) if any GE Notification Number
SC98-01
5. Deviation Identified Spring Return Binding in GE Type SBM Control
Switches
6. Vendor notified: N/A
Date: N/A
Person Contacted: N/A
7. Has vendor assume responsibility for evaluating for Part 21
applicability, and has the vendor reported the defect to NRC?
YES [] NO [X]
Completion date N/A
If YES, the evaluation is closed.
N/A N/A
Evaluating Engineer Date
N/A N/A
Evaluating Engineer Supervisor Date
If NO, then proceed by completing the remainder of the checklist.
8. Is there a Deviation as defined in Section 4.4?
Yes [X] No [ ]
Provide basis for above conclusion.
Notification of possible failure of certain GE Type SBM Control
Switches with spring return function was issued by GE as a transfer
of information pursuant to 10 CFR 21.21(b). The possible failure was
determined to meet the threshold for a substantial safety hazard
based on failure analysis indicating a substantial increase in
likelihood of switch failure where switches control the operation of
various equipment important to plant safety.
g:\nep-p21.doc
Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 1
Page 2 of 2
10CFR PART 21 EVALUATION CHECKLIST
9. Does the Deviation have the potential for impacting system,
structure, or component Operability as defined in the Technical
Specification? YES [X] NO [ ]
If NO, provide reason N/A.
If YES, Notify the appropriate Supervisor to determine if an
Operability Evaluation must be completed. Operability Assessments
have been established for all affected ComEd facilities.
10. Is 10CFR21 notification to NRC required. YES [X] NO [ ]
If YES, explain why, and which item of paragraph 5.1.1
occurred/could occur. A major deficiency involving parts which
could adversely the capability to shutdown the reactor and maintain
it in a safe shutdown condition. (Paragraph 5.1.1.A.3.)
If NO, provide basis for conclusion.
N/A.
Corrective Action which has been, is being, or will be taken.
Dresden & Quad Cities will be, replacing switches at first available
opportunity. LaSalle will be replacing binding switches at first
available opportunity and is currently evaluating scope of
additional corrective action.
This information is applicable to the following Station(s):
[ ] Braidwood [X] Dresden [X] Quad Cities
[ ] Byron [X] LaSalle [ ] Zion
This evaluation was not performed for the following Stations:
[X] Braidwood [ ] Dresden [ ] Quad Cities
[X] Byron [ ] LaSalle [X] Zion
Provide explanation for each station not evaluated.
Braidwood, Byron & Zion evaluated the concern and determined the
have no SBM switches of the subject population
Evaluation conducted by Date
Evaluating Engineer
Concur with evaluation and evaluation is closed,
Date
Evaluating Engineer Supervisor
g:\nep-p21.doc
March 16, 1998 NEP 10-02 Attachment I Item 98-01
PART 21 EVALUATION SUMMARY
GE Type SBM Control Switch Binding
- On January 23, 1998, GE issued a 10CFR Part 21.21 (b) Transfer of
information concerning the possible failure of certain GE Type SBM
Control Switches with the spring return function to reset properly
after operation. GE determined it was not possible for them to
evaluate the safety functions of the switches which are supplied to
several nuclear power plants for unspecified safety related
applications. As such, GE concluded it was not possible for them to
evaluate the safety significance of possible failures to determine
if a defect exists in the context of 10CFR Part 21.
- Commonwealth Edison determined the scope of applicability of the
reported issue to affect Dresden, LaSalle County, and Quad Cities
Stations which have two (2), two hundred forty six (246), and three
(3) of the suspect switches installed in the plant. None of the
suspect switches have been installed at Braidwood, Byron or Zion
stations.
- Dresden and Quad Cities Stations have evaluated the condition in
accordance with their site Operability Determination procedures,
have placed caution cards on the subject switches and initiated
action to replace the switches at the first available opportunity.
- LaSalle County Station evaluated the condition in light of current
plant status, with both units shutdown for extended maintenance
outages, and established operability by heightening operator
awareness through communication and is currently establishing the
scope of additional compensatory and corrective action plans to
demonstrate operability as applied to future plant operating
conditions.
- In the course of evaluating the condition reported by GE,
Commonwealth Edison concluded, in the absence of compensatory
action, the reported deviation may substantially increase the
likelihood of switch failure when compared to a nominal base case
switch failure rate without the reported condition. Since the
switches control the operation of various equipment important to
plant safety, this increase in failure probability without
compensatory action has been determined to constitute a defect
representing a substantial safety hazard per the requirements of
10CFR Part 21 and is reportable to the NRC.
Approval of this summary and the attached notification letter to the NRC
signifies appropriate notification to a Commonwealth Edison Officer as
require by 10CFR Part 21.
NEP 10-02 Attachment 1 Item 98-01 (cont'd)
R.N. Cascarano P.C. LeBlond
NES - Design Basis Programs NES - Chief, Design Basis Programs
Approved Date:
J.B. Hosmer
Engineering Vice President
Attachments
1) GE Transfer of Information Letter SC98-01 dated January 23, 1998
2) March 16,1998 Commonwealth Edison Part 21 Notification to NRC with
NEP 10-01, Exhibit A. "Part 21 Evaluation Checklist" dated March 16,
1998
GE Nuclear Energy
General Electric Company
175 "illegible print", San Jose, CA 95123
January 23, 1998
98-01NRC.DOC
MFN 011-98
Document Control Desk
United States Nuclear Regulatory Commission
Washington, DC 20555
Subject: Spring Return Binding in GE Type SBM Control Switches
This letter provides information concerning the possible failure of
certain GE Type SBM Control Switches with the spring return function to
reset properly after operation. While the failure mode has been
identified as an interference between the rear bearing and its support,
the root cause has not yet been determined and the total extent of the
problem is not fully known. Until more definitive information is
available, GE Nuclear Energy (GE-NE) is conservatively assuming that SBM
Control Switches with the spring return function manufactured since March
1996 may be subject to this failure mode. GE-NE is undertaking a test
program to determine the root cause failure mechanism and appropriate
remedial action (s), but the results of the investigation may not be
complete for several weeks. Additional information will be provided when
it is available.
GE Type SBM Control Switches are manufactured by GE Electrical
Distribution and Control (GE-ED&C;) Power Management, Malvern, PA as
commercial grade items. GE-NE has dedicated these switches and supplied
them to several licensees as basic components for unspecified, safety
related applications. Since the specific applications and associated
safety functions of the switches are not known to GE-NE, we have
transferred information pursuant to 10 CFR Part 21.21 (b) to those
licensees known to be affected. However, since additional licensees may
have obtained these devices through other dedicating entities, we cannot
assure ourselves that all end-users have been notified. We are therefore
providing this information to the NRC for appropriate action.
On January 6, 1998, GE-NE was advised by a licensee that a safety related
SRM Control Switch with the spring return function had failed to reset
(return to normal position) properly. The switch (model
16SBMB3A02S152P1) was returned to GE-NE for evaluation with the support
of GE-ED&C; Relay Product Engineering.
The most probable failure mode was determined to be binding caused by
interference between the rear brass bearing and the phenolic rear bearing
support. Subsequently, a second failed switch was returned, and
examination confirmed the same failure mode. In addition, there have
been at least nine more switches identified by the licensee as failing to
reset properly after operating correctly for approximately one year.
Based on the preliminary investigation, the root cause is suspected to be
"post mold cure" shrinkage of the phenolic material used to construct
some of the switch components. The failed devices have been examined
and, in each instance, the bearing support hole was found to be
undersized and the bearing was at, or near, its maximum allowable
diameter. Devices with bearing that are at their nominal diameter
function properly, even when the support hole is undersized.
Consequently, the failure is not seen in every switch. The failure is
most likely preceded by a gradual increase in the force required to
operate the device and a sluggish return.
Although the interference can exist in any SBM Control Switch, binding is
primarily an issue in those devices that have the spring return function.
In spring return switches, the reset spring does not generate enough
torque on the operating shaft to overcome the friction resulting from the
interference. Thus, the operating handle, and consequently the contacts,
will not reset when the handle is released. The switch contacts will
function when the switch is operated failed, if the switch is manually
returned to the reset (normal) position, the contacts will also return to
their normal configuration. "Maintain position" SBM Control switches may
also have the interference, but the force required to overcome the
friction resulting from the interference is not great enough to prevent
proper function. Nonetheless, it is considered good practice to assure
that these switches are in the proper position, as indicated by the match
pointer, before releasing the handle.
A loss of torque in the tie bolts that secure the switch components has
been observed in conjunction with the spring return binding. The loss of
bolt torque is also postulated to be the result of the post mold cure
shrinkage and, although it has been noted in those devices that have
failed, it is not the cause of the binding and does not indicate
impending failure.
All of the failed switches identified to date were manufactured in the
period November 1996 through February 1997. There have been no reports
of spring return binding in earlier SBM Control Switches, despite the
fact that these switches have been widely used in a variety of
application for many years. Until more definitive information is
available concerning the root cause, GE-NE is conservatively assuming
that SBM Control Switches with the spring return function manufactured
since March 1996 may be subject to this failure mode. The affected
2
date codes are PL, RL, SL, TL, UL, VL, WL, XL, YL, ZL, NM, OM, PM, RM,
SM, UM, VM, WM, XM, YM, ZM, and NN.
There are two safety concerns with regard to spring return binding: (1)
possible damage to control circuitry caused by the circuit being
maintained in the energized state for a prolonged period; and (2) the
possibility that control circuit will be prevented from performing their
paper function by the failure of the switch contacts to return to their
reset (normal) configuration.
The consequences of the loss of torque in the tie bolts that secure the
switch components, and the resulting effect on the switch qualification,
have been evaluated. The evaluation determined that the loss of torque
will not prevent proper operation or degrade the device qualification.
If SBM Control Switches with the spring return function, and manufactured
since March 1998, have been installed in safety related applications, it
is suggested that station personnel who operate these switches be advised
to return the operating handle to the normal position after Operation.
This will preclude any control circuit difficulties. It should be noted
that all of the switches identified to date as failing to reset properly
had previously operated correctly for approximately one year.
Additional information will be made available when GE-NE has completed
the test program to determine the root cause failure mechanism and
appropriate remedial [illegible print].
If you have any questions, please call me at (408) 925-1010.
Sincerely,
Michael A. Smith, Program Manager
Safety Evaluations
cc: S. D. Alexander (NRC-NRR/DISP/PSIB)
G. C. Cwalina (NRC-NRR/DISP/PSIB)
J. F. Quirk (GE-NE)
H. J. Neems (GE-NE)
G. W. Sanders (GE-NE)
J. A. Steininger (GE-NE)
J. Teague (GE ED&C;/Malvern)
GE-NE PRC File
3
10 CER Part 21 Notification
GE Nuclear Energy
SC98-01 January 23, 1998
To: BWR and PWR Utilities (per Attachment 1)
Subject: Spring Return Binding in GE Type SBM Control Switches
[ ] Reportable Condition [21.21(d)] [ ] 60 Day Interim Report
[21.21(a)(2)]
[x] Transfer of Information [21.21(b)] [ ] Safety Information
Communication
Summary
This Notification provides information concerning the possible failure of
certain GE Type SBM Control Switches with the spring return function to
reset properly after operation. While the failure made has been
identified as an interference between the rear bearing and its support,
the root cause has not yet been determined and the total extent of the
problem is not fully known. Until more definitive information is
available, GE Nuclear Energy is conservatively assuming that SBM Control
Switches with the spring return function manufactured since March 1996
may be subject to this failure mode.
GE Type SBM Control Switches are manufactured by GE Electrical
Distribution and Control (GE-ED&C;) Power Management, Malvern, PA as
commercial grade items. GE Nuclear Energy (GE-NE) has dedicated these
switches and supplied them to several nuclear power plants for,
unspecified, safety related applications. Since the specific application
and associated safety functions of the switches are not known, it is not
possible for GE-NE to evaluate the safety sign of possible failures to
determine if a defect exists in the context of 10CFR Part 21. We are
therefore transferring the available information to the known affected
utilities for evaluation.
GE-NE is undertaking a test program to determine the root cause failure
mechanism and appropriate remedial action (s), but the results of the
investigation may not be complete for several weeks. A supplement or
revision to this 10CFR Part 21 Notification will be issued when
additional information is available.
Issued by:
M. A. Smith, Program Manager
Safety Evaluations
GE Nuclear Energy, M/C 187
175 Curtner Avenue, San Jose, CA 95115
(408) 925-1019
[Illegible print]
SC98-01
Background
GE Type SBM Control Switches are manufactured by GE-ED&C; Power
Management. Malvern, PA as commercial grade items. GE-NE dedicates
these switches and supplies them to nuclear power plants as basic
components for safety related applications.
On January 6, 1998, GE-NE was advised by a licensee that a safety related
SBM Control Switch with the spring return function had failed to reset
(return to normal position) properly. The switch (model
16SBMB3A02S1S2P1) was returned to GE-NE for evaluation with the support
of GE-ED&C; Relay Product Engineering.
The most probable failure mode was determined to be binding caused by
interference between the rear brass bearing and the phenolic rear bearing
support. Subsequently, a second failed switch was returned, and
examination confirmed the same failure mode. In addition, there have
been at least nine more switches identified by the licensee as failing to
reset properly after operating correctly for approximately one year.
Based an the preliminary investigation, the root cause is suspected to be
"past mold cure" shrinkage of the phenolic material used to construct
some of the switch components. The failed devices have been examined
and, in each instance, the bearing support hole was found to be
undersized and the bearing was at, or near, its maximum allowable
diameter. Devices with bearings that are at their nominal diameter
function properly, even when the support hole is undersized.
Consequently, the failure is not seen in every switch. The failure is
most likely preceded by a gradual increase in the force required to
operate the device and a sluggish return.
Although the interference can exist in any SBM Control Switch, binding is
primarily an issue in those devices that have the spring return function.
In spring return switches, the reset spring does not generate enough
torque an the operating shaft to overcome the friction resulting from the
interference. Thus, the operating handle, and consequently the contacts
will not reset when the handle is released. The switch contacts will
function when the switch is operated and, if the switch is manually
returned to the reset (normal) position, the contacts will also return to
their normal configuration. "Maintain position" SBM Control Switches may
also have the interference, but the force required to overcome the
friction resulting from the interference is not great enough to present
proper function. Nonetheless, it is considered good practice to assure
that these switches are in the proper position, as indicated by the
switch pointer, before releasing the handle.
A loss of torque in the tie bolts that secure the switch components has
been observed in conjunction with the spring return binding. The loss of
bolt torque is also postulated to be the result of the post mold cure
shrinkage and, although it has been noted in those devices that have
failed, it is not the cause of the binding and does not indicate
impending failure.
2
SC98-01
All of the failed switches identified to date were manufactured in the
period November 1996 through February 1997. There have been no reports
of spring return binding in earlier SBM Control Switches, despite the
fact that these switches have been widely used in a variety of
applications for many years. Until more definitive information is
available concerning the root cause, GE-NE is conservatively assuming
that SBM Control Switches with the spring return function manufactured
since March 1996 may be subject to this failure mode. The affected date
codes am PL, RL, SL, TL, UL, VL, WL XL, YL, ZL, NM, OM, PM, RM, SM, TM,
UM, VM, WM, XM, YM, ZM, and NN.
Safety Basis
There are two safety concerns with regard to spring return binding: (1)
possible damage to control circuitry caused by the circuit being
maintained in the energized state for a prolonged period; and (2) the
possibility that control circuits will be prevented from performing their
proper function by the failure of the switch contacts to return to their
reset (normal) configuration.
The consequences of the loss of torque in the tic bolts that secure the
switch components, and the resulting effect on the switch qualification,
have been evaluated. The evaluation determined that the loss of torque
will not prevent proper operation or degrade the device qualification.
Corrective Actions and Preventive Measure
If SRM Control Switches with the spring return function, and manufactured
since March 1996, have been installed in safety related applications, it
is suggested that station personnel who operate these switches be advised
to return the operating handle to the normal position after operation.
This will preclude any control circuit difficulties.
It should be noted that all of the switches identified to date as failing
to reset properly had previously operated correctly for approximately one
year.
Additional information will be made available when GE-NE has completed
the test program to determine the root cause failure mechanism and
appropriate remedial action(s).
3
SC98-01
Attachment 1 - Affected Plants
Utility Plan
x Boston Edison Co Pilgrim
Carolina Power & Light Co. Brunswick 1
Carolina Power & Light Co. Brunswick 2
Centerior Energy Perry 1
x ComEd CRIT Facility
x ComEd Dresden 2
x ComEd Dresden 3
x ComEd LaSalle 1
x ComEd LaSalle 2
x ComEd Quad Cities 1
x ComEd Quad Cities 2
Consumers Power Co. Big Rock Point
DTE Energy Fermi 2
Entergy Operations, Inc. Grand Golf
x Entergy Operations, Inc. River Bend
x GPU Nuclear Corp. Oyster Creek
IES Utilities, Inc. Duane Arnold
Illinois Power Co. Clinton
x Nebraska Public Power District Cooper
x New York Power Authority FitzPatrick
Niagara Mohawk Power Corp. Nine Mile Point 1
Niagara Mohawk Power Corp. Nine Mile Point 2
x Northern Utilities Millstone 1
Northern States Power Co. Monticello
PECO Energy Co. Limerick 1
PECO Energy Co. Limerick 2
PECO Energy Co. Peach Bottom 2
PECO Energy Co. Peach Bottom 3
Pennsylvania Power & Light Co. Susquehanna 1
Pennsylvania Power & Light Co. Susquehanna 2
Pooled Equipment Inventory Co. FIM
Public Service Electric & Gas Co. Hope Creek
x Southern Nuclear Operating Co. Hatch 1
x Southern Nuclear Operating Co. Hatch 2
x Tennessee Valley Authority Browns Ferry 1
x Tennessee Valley Authority Browns Ferry 2
x Tennessee Valley Authority Browns Ferry 3
x Vermont Yankee Nuclear Power Corp. Vermont Yankee
Washington Public Power Supply WNP-2
System
4
SC-98-01
Attachment 1 - Affected Plants
Utility Plan
x Consumers Power Co. Palisades
x Entergy Operations, Inc. Arkansas Nuclear One 1
x Entergy Operations, In. Arkansas Nuclear One 2
x Florida Power & Light Co. Turkey Point 3
x Florida Power & Light Co. Turkey Point 4
x Florida Power & Light Co. Crystal River 3
x Maine Yankee Atomic Power Co. Maine Yankee
x New York Power Authority Indian Point 5
x North Atlantic Energy Service Corp. Seabrook
x Omaha Public Power District Fort Calhoun
x Public Service Electric & Gas Co. Salem 1
x Public Service Electric & Gas Co. Salem 2
x Southern Nuclear Operating Co. Vogtle 1
x Southern Nuclear Operating Co. Vogtle 2
5
SC98-01
Attachment 2 - 10 CFR Part 21 Notification for 1997/98
The following is a list of 10 CFR Part 21 Notifications that GE Nuclear
Energy has provided to affected licensees in 1997 and 1999 as Reportable
Conditions (RC), Transfers of Information (TI), Safety Information
Communications (SC) or 60 Day Interim Reports (60 Day).
6
ComEd
1400 OPUS Place
Downers Grove, IL 60515
TRANSMITTAL SHEET
DATE:
TO:
Organization Station Departments
FROM:
Department: NUCLEAR LICENSING
Telephone Number: (630) 663-
Transmittal Sheet Plus ___________ Page(s)
Telecopy Number:
If you have any problems receiving your telecopy, please call (630) 663-
7332
_________________________________________________________________________
NOTES
Faxed by
Time:
Confirmed
k:lic faxcov.doc
GENERAL INFORMATION or OTHER EVENT NUMBER: 33917
LICENSEE: COMMONWEALTH EDISON NOTIFICATION DATE: 03/18/98
CITY: DOWNERS GROVE REGION: 3 NOTIFICATION TIME: 16:37 [ET]
COUNTY: STATE: IL EVENT DATE: 03/16/98
LICENSE#: AGREEMENT: Y EVENT TIME: 00:00[CST]
DOCKET: LAST UPDATE DATE: 03/18/98
NOTIFICATIONS
MELVYN LEACH, REG 3 RDO
NRC NOTIFIED BY: GINA DISON VERN HODGE NRR
HQ OPS OFFICER: LEIGH TROCINE RICHARD BARKLEY R1DO
THOMAS JOHNSON R2DO
EMERGENCY CLASS: NOT APPLICABLE LAWRENCE YANDELL R4DO
10 CFR SECTION:
CCCC 21.21 UNSPECIFIED PARAGRAPH
EVENT TEXT
10CFR PART 21 NOTIFICATION REGARDING SPRING RETURN BINDING IN
GENERAL
ELECTRIC (GE) TYPE SBM CONTROL SWITCHES AT DRESDEN, LASALLE, AND
QUAD
CITIES.
THIS NOTIFICATION REFERENCED A GE NUCLEAR ENERGY TRANSFER OF
INFORMATION
DATED JANUARY 23, 1998, AND IT INVOLVES GE TYPE SBM CONTROL SWITCHES
WITH
THE SPRING RETURN FUNCTION MANUFACTURED SINCE MARCH 1996. THESE
SWITCHES
ARE SUSCEPTIBLE TO BINDING WHICH MAY PREVENT SPRING RETURN TO RESET
(RETURN TO NORMAL POSITION). THE CAUSE OF THE BINDING WAS
ATTRIBUTED TO
FAILURE TO ACCOUNT FOR 'POST-MOLD CURE' SHRINKAGE IN THE DESIGN
TOLERANCE
OF THE CLEARANCE BETWEEN THE PHENOLIC REAR BEARING SUPPORT HOLE
AND THE
BEARING. THIS DESIGN ERROR DID NOT BECOME APPARENT UNTIL THE MOLDS
EXPERIENCED WEAR TO THE EXTENT THAT RESULTING PARTS WERE AT THE
EXTREMES
OF DIMENSIONAL TOLERANCES. THE POST-MOLD CURE IS NORMAL FOR
PHENOLIC
MATERIAL AND HAS BEEN SHOWN TO TAKE PLACE OVER A PERIOD OF UP TO
TWO
YEARS AFTER MOLDING IS COMPLETED. CONSEQUENTLY, SWITCHES WHICH
ARE
CONSTRUCTED FROM COMPONENTS THAT ARE WITHIN SPECIFICATION AND
FUNCTION
FULLY DURING ACCEPTANCE TESTING MAY EXHIBIT SLUGGISH RETURN OR
BINDING UP
TO TWO YEARS AFTER ASSEMBLY. THIS ROOT CAUSE IS SUPPORTED THROUGH
GE
EXAMINATION OF FAILED SWITCHES WHICH, IN EACH INSTANCE, HAS FOUND
THE
BEARING SUPPORT HOLE TO BE UNDERSIZED (LESS THAN MINIMUM INSIDE
DIAMETER)
AND THE BEARING AT OR NEAR ITS MAXIMUM ALLOWABLE DIAMETER. GE
TESTING
HAS ALSO CONFIRMED THAT SWITCHES WITH BEARINGS THAT ARE AT THEIR
NOMINAL
DIAMETER WILL FUNCTION PROPERLY EVEN WHEN THE SUPPORT HOLE IS
UNDERSIZED.
CONSEQUENTLY, THE FAILURE IS NOT SEEN IN EVERY SWITCH.
COMMONWEALTH EDISON HAS DETERMINED THAT THE SUSPECT SBM SWITCHES
ARE NOT
INSTALLED AT ITS BRAIDWOOD, BYRON, OR ZION NUCLEAR GENERATING
STATIONS.
(Continued on next page)
LICENSEE: COMMONWEALTH EDISON PAGE # 2 OF EVENT NUMBER: 33917
HOWEVER, COMMONWEALTH EDISON NUCLEAR GENERATING STATIONS WHICH
HAVE THE
SUSPECT SAFETY-RELATED SPRING RETURN SWITCHES INCLUDE DRESDEN,
LASALLE,
AND QUAD CITIES WITH 2, 246, AND 3 SWITCHES INSTALLED, RESPECTIVELY.
LASALLE IS CURRENTLY EXPERIENCING BINDING IN 21 OF THESE SWITCHES.
THE FOLLOWING FACILITIES WERE ALSO REPORTED TO BE AFFECTED: PILGRIM;
RIVER BEND; OYSTER CREEK; COOPER; FITZPATRICK; MILLSTONE UNIT 1; HATCH
UNITS 1 AND 2; BROWNS FERRY UNITS 1, 2, AND 3; VERMONT YANKEE;
PALISADES;
ARKANSAS NUCLEAR ONE UNITS 1 AND 2; TURKEY POINT UNITS 3 AND 4;
CRYSTAL
RIVER UNIT 3; MAIN YANKEE; INDIAN POINT 3; SEABROOK; FORT CALHOUN;
SALEM
UNITS 1 AND 2; AND VOGTLE UNITS 1 AND 2.
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Page Last Reviewed/Updated Wednesday, March 24, 2021