Information Notice 1987-61, Failure of Westinghouse W-2-Type Circuit Breaker Cell Switches
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
December 7, 1987
NRC INFORMATION NOTICE NO. 87-61:
FAILURE OF WESTINGHOUSE W-2-TYPE
CIRCUIT BREAKER CELL SWITCHES
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice is being provided to alert addressees to potential
problems resulting from the failure of Westinghouse W-2-type circuit breaker
cell switches. It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate, to
avoid similar problems.
However, suggestions contained in this information
notice do not constitute NRC requirements; therefore, no specific action or
written response is required.
Description of Circumstances
On October 16, 1987, Westinghouse Electric Corporation notified the Nuclear
Regulatory Commission (NRC) staff, pursuant to the requirements of 10 CFR
Part 21, of the failure of a modified Westinghouse W-2-type switch that was
being utilized as a circuit breaker cell switch.
The failure was identified
at Indian Point Station, Unit 3, on May 15, 1987, while the reactor was at
cold shutdown for a scheduled refueling outage.
The output breaker for
emergency diesel generator (EDG) No. 31 was prevented from re-energizing
the 480-volt bus 2A after plant personnel had inadvertently de-energized
480-volt buses 2A and 5A.
Subsequent investigation by the licensee determined
that an erroneous input to the EDG logic system had prevented the EDG output
breaker from closing. The licensee identified deformation of the spring
retainer in the spring-return mechanism of the cell switch in the 52/2A
breaker cell as the root cause of the erroneous input.
The spring retainer is continuously under stress whenever the breaker is
racked in (which it is, except when the breaker is racked out for testing
or maintenance) and releases whenever the breaker is racked out.
Its
deformation allowed a loss of spring tension that rendered the cell switch
unable to spring-return to the racked out position when normal supply breaker
52/2A was racked out for maintenance. Thus, the EDG logic system received an
erroneous input indicating that breaker 52/2A was racked in and the main con- tacts were still closed.
This erroneous input prevented the EDG No. 31 output
breaker from closing automatically in response to a loss of power.
During
872106Z
IN 87-61 December 7, 1987 subsequent inspections by Indian Point personnel, 35 of a total of 37 similar
W-2-type switch spring retainers in the 480-volt system breakers exhibited
some sign of deformation.
All the cell switches had been shipped to Indian Point in 1971-1972 and all had
been in service for close to 15 years.
The licensee reported the results of its
investigation to the NRC in Licensee Event Report 87-009-00 on October 2, 1987.
Discussion:
Westinghouse has determined (1) that the deformation of the spring retainer in
the spring-return mechanism of the cell switches was related to the aging of
the component and (2) that the failure mechanism was the continuous stress it
experiences while the breaker is racked in. The W-2-type cell switches are
available as optional equipment for all Westinghouse DS switchgear cabinets.
Westinghouse has indicated that inspection or testing performed. when the
breaker is racked out would determine if a failure has occurred.
Where inspec- tions and/or testing have not been performed, the potential exists that if the
breaker is not racked in, a cell switch malfunction may prevent the completion
of safety-related functions dependent on cell switch indication of the breaker
being racked out or in the test position.
In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recommends
that proper cell switch operation'be verified through periodic inspections or
testing, or whenever the breaker is racked out.
Proper operation of the spring
retainer- is only veriffable-when the-breaker--is-moved- fromr-ts-racked-iin-position.--
Visible inspection may be used to verify cell switch operation.
However, it will
be necessary to move the breaker out on the rails to observe whether the switch
operating lever is in its proper position (30 degrees off. vertical for the W-2 cell switch).
Any uncertainty in this observation may be resolved by manually
ensuring that the switch has returned to the proper position.
Persons performing
this inspection should use caution not to contact any energized terminals.'
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
ares E.Rossi, Director
Division of 'Operational Events Assessment
Office of Nuclear Reactor'Regulation
Technical Contacts: K. R. Naidu, NRR
(301) 492-9656
Jaime Guillen, NRR
(301) 492-8933 Attachment:
List of Recently Issued NRC Information Notices
Attachment
December 7, 1987
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES 1987
Information
Date of
Notice No.
Subject
Issuance
Issued to
87-60
86-108, Supp. 2
87-59
87-58
Depressurization of Reactor
Coolant Systems in
Pressurized-Water Reactors
Degradation of Reactor
Coolant System Pressure
Boundary Resulting from
Boric Acid Corrosion
Potential RHR Pump Loss
Continuous Communications
Following Emergency
Notifications
Loss of Emergency Boration
Capability Due to Nitrogen
Gas Intrusion
12/4/87
11/19/87
11/17/87
11/16/87
All holders of OLs
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All nuclear power
reactor facilities
holding an OL and
the following fuel
facilities that have
Emergency Notification
Systems:
Nuclear
Fuel Services, Erwin, TN; General Atomics, San Diego, CA; UNC,
Montville, CT; and
B & W LRC and B & W
Navy, Lynchburg, VA.
All holders of OLs
or CPs for nuclear
power reactors.
!:
-~ .:
-, .-
87-57
11/6/87
87-56
Improper Hydraulic Control
Unit Installation at BWR
Plants.
11/4/87
All holders of OLs
or CPs for boiling
water reactors (BWRs).
87-55
87-54 Portable Moisture/Density
Recent Incidents
of Portable Gauges Being
Stolen or Lost
Emergency Response Exercises
10/29/87
10/23/87
All NRC licensees
authorized to
possess portable
All holders of OLs
or CPs for nuclear
power reactors.
OL = Operating License
CP = Construction Permit
IN 87-61 December 7, 1987 subsequent inspections by Indian Point personnel, 35 of a total of 37 similar
W-2-type switch spring retainers in the 480-volt system breakers exhibited
some sign of deformation.
All the cell switches had been shipped to Indian Point in 1971-1972 and all had
been in service for close to 15 years.
The licensee reported the results of its
investigation to the NRC in Licensee Event Report 87-009-00 on October 2, 1987.
Discussion:
Westinghouse has determined (1) that the deformation of the spring retainer in
the spring-return mechanism of the cell switches was related to the aging of
the component and (2) that the failure mechanism was the continuous stress it
experiences while the breaker is racked in. The W-2-type cell switches are
available as optional equipment for all Westinghouse DS switchgear cabinets.
Westinghouse has indicated that inspection or testing performed when the
breaker is racked out would determine if a failure has occurred.
Where inspec- tions and/or testing have not been performed, the potential exists that if the
breaker is not racked in, a cell switch malfunction may prevent the completion
of safety-related functions dependent on cell switch indication of the breaker
being racked out or in the test position.
In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recommends
that proper cell switch operation be verified through periodic inspections or
testing, or whenever the breaker is racked out.
Proper operation of the spring
retainer is only verifiable when the breaker is moved from its racked in position.
Visible inspection may be used to verify cell switch operation.
However, it will
be necessary to move the breaker out on the rails to observe whether the switch
operating lever is in its proper position (30 degrees off vertical for the W-2 cell switch).
Any uncertainty in this observation may be resolved by manually
ensuring that the switch has returned to the proper position.
Persons performing
this inspection should use caution not to contact any energized terminals.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: K. R. Naidu, NRR
(301) 492-9656
Jaime Guillen, NRR
(301) 492-8933 Attachment:
List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- OGCB:DOEA:NRRtVIB:DRIS:NRR *SELB:DEST:NRR*PPMB:ARM*C/OGCB:DOEA:NRR
NR
JGuillen
KNaidu
FRosa
TechEd
CHBerlinger
CERossi
11/03/87
11/
/87
11/06/87
10/31/87 11/20/87
12// /87
IN 87-XX
November xx, 1987 All the cell switches had been shipped to Indian Point In 1971-1972 and all had
been in service for close to 15 years. The licensee reported the results of
its investigation to the NRC in Licensee Event Report 87-009-00 on October 2,
1987.
Discussion:
Westinghouse has determined (1) that the deformation of the spring retainer in
the spring-return mechanism of the cell switches was related to the aging of
the component and (2) that the failure mechanism was the continuous stress it
experiences while the breaker is racked in. The W-2-type cell switches are
available as optional equipment for all Westinghouse DS switchgear cabinets.
Westinghouse has indicated that inspection or testing performed when the
breaker is racked out would determine if a failure has occurred. Where inspec- tions and/or testing have not been performed, the potential exists that if the
breaker is not racked in, a cell switch malfunction may prevent the completion
of safety-related functions dependent on cell switch indication of breaker
racked out or test position.
In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recom- mends that proper cell switch operation be verified through periodic inspec- tions or testing, or whenever the breaker is racked out. Proper operation of
the spring retainer is only verifiable when the breaker is moved from its
racked in position. Visible inspection may be used to verify cell switch
operation. However, it will be necessary to move the breaker out on the rails
to observe whether the switch operating level is in its proper position (30
degrees off vertical for the W-2 cell switch). Any uncertainty in this obser- vation may be resolved by manually ensuring that the switch has returned to the
proper position. Persons performing this inspection should use caution not to
contact any energized terminals.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: K. R. Naidu, NRR
(301) 492-9656
Jaime Guillen, NRR
(301) 492-8933 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
0
- OGCB:DOEA:NRR RVIB:DRIS:NRR *SELB: ET:NRR*PPMB:ARM C/OG
- NRR D/DOEA:NRR
JGuillen
KNaidu
FRosa
4<-TechEd
CHBerlinger
CERossi
11/03/87
11/ /87
11/06/ 7ifr-10/31/87 11//87
11/ /87
IN 87-XX
November xx, 1987 All the cell switches had been shipped to Indian Point in 1971-1972 and all had
been in service for close to 15 years. The licensee reported the results of
its investigation to the NRC in Licensee Event Report 87-009-00 on October 2,
1987.
Discussion:
Westinghouse has determined (1) that the deformation of the spring retainer in
the spring-return mechanism of the cell switches was related to the aging of
the component and (2) that the failure mechanism was the continuous stress it
experiences while the breaker is racked-in.
The W-2-type cell switches are
available as optional equipment for all Westinghouse DS switchgear cabinets.
Westinghouse has indicated that inspection or testing performed when the
breaker is moved from the "connected" position would determine if a failure has
occurred. Where inspections and/or testing has not been performed, the poten- tial exists that if the breaker is not racked in, a cell switch malfunction may
prevent the completion of safety-related functions dependent on cell switch
indication of breaker position.
In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recom- mends that proper cell switch operation be verified through periodic inspec- tions or testing, or whenever the breaker is removed from its connected"
position. Proper operation of the spring retainer is only verifiable when the
breaker is moved from its racked in position. Visible inspection may be used
to verify cell switch operation. However, it will be necessary to move the
breaker out on the rails to observe whether the switch operating level is In
its proper position (30 degrees off vertical for the W-2 cell switch).
Any
uncertainty in this observation may be resolved by manually ensuring that the
switch has returned to the proper position. Persons performing this Inspection
should use caution not to contact any energized terminals.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: K. R. Naidu, NRR
(301) 492-9656
Jaime Guillen, NRR
(301) 492-8933 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- OGCB:DO EA:NRR RVIB:DRIS:NRR *Sw ~jbT:NRR*PPMB:ARM C/OGCB:DOEA:NRR D/DOEA:NRR
JGui
KNaidu
FR.
TechEd
CHBerlinger
CERossi
11/0I3
11/ /87
7/!7 10/31/87 11/
/87
11/
/87
I .
.
I
IN 87-XX
October xx, Page 2 of
1987 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
K~a+m
R. Naidu, NRR
(301) 492-9656
Jaime Guillen, NRR
(301) 492-8933 Attachment:
List of Recently Issued NRC Information Notices
OGCB:DOEA:NRR
JGuillen
10/ /87 RVIB:DRIS:NRR SELB:DEST:NRR
KNaidu
FRosa
10/ /87
10/ /87 PPMB:ARM C/OGCB: DOEA:NRR
TechEdat tCHBerlinger
10/3//87 10/ /87 D/DOEA:NRR
CERossi
10/ /87