Information Notice 1987-41, Failures of Certain Brown Boveri Electric Circuit Breakers
SSINS No.:
6835
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
August 31, 1987
NRC INFORMATION NOTICE NO. 87-41: 'FAILURES OF CERTAIN BROWN BOVERI
ELECTRIC CIRCUIT BREAKERS
Addressees
All nuclear power reactor facilities holding an operating license or a con- struction permit.
Purpose
This information noticetis provided to inform recipients of failures of certain
Brown Boveri Electric (BBE) circuit breakers.
It is expected that recipients
will review the information for applicability and consider actions, if appro- priate, to preclude similar problems from occurring at their facilities. Sug- gestions' contained in'this notice do not'constitute NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
Concerns regarding BBE circuit breakers' have been recently reported to the NRC.
On April 20, 1987','Duquesne Light Company, the Beaver Valley Unit 2 licensee, notified the NRC in accordance with the reporting requirements of 10 CFR 50.55(e)
of the failure of a BBE Type 5HK Class IE 4-KV circuit breaker. When the circuit
breaker was racked onto the bus and 125-V DC control power was applied to the
breaker's control circuit, the closing spring charged and the circuit breaker
immediately closed and opened several times before the control power could be
turned off.
The-licen'see determined by field testing that the closing coil was
not being energized.
Another problem with BBE circuit breakers occurred 'at River'Bend and was
reported in Licensee Event Report (LER)87-004, dated March 6, 1987. On
February 6, 1987, with the unit at full power, the Division I diesel generator
4.16-KV output circuit'breaker (Gould-Brown Boveri Type 5HK) failed to close
during a weekly surveillance test. The licensee's inspection of the output
circuit breaker revealed that a mounting bolt had fallen out of the closing
spring charging motor, rendering the motor inoperable.
Further investigation
revealed several other circuit breakers that contained loose or missing charg- ing motor mounting bolts.
The licensee also stated that the River Bend circuit
breaker preventive maintenance program, which the licensee believes to be in
accordance with the vendor's recommendations, did not detect this problem.
The
licensee believes the root cause of the problem to be insufficient torquing of
the charging motor mounting bolts by the vendor.
.a /}
8708250191
_', II
u....
>1
IN 87-41 August 31, 1987 Discussion:
With regard to the repeated closing and opening of the breaker, this problem
was also reported to the NRC in accordance with the reporting requirements of
10 CFR 50.55(e) by Philadelphia Electric Company, for Limerick Unit 1, in 1983.
The circuit breakers involved were returned-to BBE for analysis, and BBE
transmitted its findings to the NRC in a letter dated April 20, 1983.
BBE
stated that 'the repeated closing and opening of the circuit breaker can be
corrected by the addition of a light spring to the close latch in the circuit
breaker operating mechanism. BBE also stated that, depending upon the year
of manufacture, circuit breakers may or may not have been originally supplied
with this spring.
BBE recommended that these springs be installed in circuit
breakers that were not originally supplied with one.
This problem may also
affect BBE Type 7.5HK, 15HK, and 38HK circuit breakers. Although information
regarding this problem has been distributed by BBE and the Institute for Nuclear
Power Operations (INPO),
the Beaver Valley event indicates that this problem
still exists.
Licensees and applicants may wish to contact BBE to obtain ad- ditional information regarding this problem and appropriate corrective actions.
Failure of a circuit breaker to fully close on demand, inadvertent closure of
a circuit breaker, or loose or missing closing spring charging motor mounting
bolts could result in a circuit breaker not performing its intended function.
This, in turn, could result in the loss of a power supply (such as a vital bus
or a diesel generator).
..
_
_ --
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate regional office or this office.
arles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jack Ramsey, NRR
(301) 492-9081 Attachment:
List of Recently Issued NRC Information Notices
I
I
LIST OF RECENTLY ISSUED
INFORMATION NOTICES 1987 Attachment
August 31, 1987
Information
Date of
Notice No. -
Subject '
-Issuance
Issued to
87-40
Backseating Valves Routinely
to Prevent Packing Leakage
8/31/87
All nuclear power
reactor, facilities
87-39 Control of Hot Particle
8/21/87
Contamination at Nuclear
Power Plants
'
All nuclear power
reactor facilities
and spent fuel
storage facilities
holding an NRC
license or CP.
87-38
87-37
. 1 Inadequate or Inadvertent
8/17/87
--
Blocking of Valve Movement
All nuclear power
reactor facilities
Compliance with the General
License Provisions of
8/10,
.:
87-36
87-35
87-34 Significant Unexpected
8/4/.
Erosion of Feedwater Lines
Reactor Trip Breaker,
7/30
Westinghouse Model DS-416,
Failed to Open on Manual
Initiation from the Control
Room
'87 All persons specifi- cally licensed to
manufacture or to
initially transfer
devices containing
radioactive material
to general licensees, as defined in 10 CFR
Part 31.
87
All nuclear power
reactor facilities
/87
All nuclear power
reactor facilities
holding an OL or
CP employing W DS-416 reactor trip breakers.
./87
All holders of an
pressurized water
reactor facilities.
Single Failures in Auxiliary
Feedwater Systems
7/24
87-33
Applicability of 10 CFR
Part 21 to Nonlicensees
7/24/87 All NRC licensees.
0
Operating License
CP = Construction Permit
K)
Attachment
August 31, 1987
L
IN
Information
Notice No.
Subject
87-39
Control of Hot
Contamination
Power Plants
87-38
Inadequate or
Blocking of Va
87-37
Compliance witl
License Provisl
IST OF RECENTLY ISSUED
FORMATION NOTICES 1987
.. -34-5
57 Issuance
Issued to
Particle
8/21/87
All nuclear power
at Nuclear
reactor facilities
and spent fuel
storage facilities
hoiding an NRC
licensi or CP.
Inadverttnt
8/17/87
?
All nuclear power
lye Movement
reactor facilities
h the General
8/10/87 All persons specifi- Ions of
cally licensed to
manufacture or to
initially transfer
devices containing
radioactive material
to general licensees, as defined in 10 CFR
Part 31.
expected
8/4/87
All nuclear power
water Lines
reactor facilities
svaker,
7/30/87
All nuclear power
odel DS-416, reactor facilities
on Manual
-
holding an OL or
r the Control
CP employing W DS-416 reactor trip Breakers.
in Auxiliary 7/24/87
All holders of an
Ms
OL or a CP for
pressurized water
reactor facilities.
87-36
87-35
87-34
87-33
87-32
Significant Uni
Erosion of Feec
Reactor Trip Br
Westinghouse Mc
Failed to Open
Initiation from
Room
Single Failures
Feedwater Syste
Applicability o
Part 21 to Nonl
Deficiencies in
of Nuclear-Grad
Charcoal.
f 10 CFR
7/24/87 I censees
the Testing
7/10/87
Ie Activated
All NRC licensees
All nuclear powen
reactor facilities
OL s Operating License
- Construction Permit
UNITED STATES
AIUCL9A
REGULATORY COMMISSION
WASHINGTON, D.C. 055
OFFICIAL BUSINESS
PfEtLTY FOR PRIVATE USE. *M
.1 . . .
FIRST-CLASS MAIL
POSTAGE & FEES PAID
l
WASH. 0. C.
PERMIT No G j67
. I , Z
-
a
I
IN 87-41 August 31, 1987 Discussion:
With regard to the repeated closing and opening of the breaker, this problem
was also reported to the NRC in accordance with the reporting requirements of
10 CFR 50.55(e) by Philadelphia Electric Company, for Limerick Unit 1, in 1983.
The circuit breakers involved were returned to BBE for analysis, and BBE
transmitted its findings to the NRC in a letter dated April 20, 1983.
BBE
stated that the repeated closing and opening of the circuit breaker can be
corrected by the addition of a light spring to the close latch in the circuit
breaker operating mechanism.
BBE also stated that, depending upon the year
of manufacture, circuit breakers may or may not have been originally supplied
with this spring. BBE recommended that these springs be installed in circuit
breakers that were not originally supplied with one.
This problem may also
affect BBE Type 7.5HK, 15HK, and 38HK circuit breakers.
Although information
regarding this problem has been distributed by BBE and the Institute for Nuclear
Power Operations (INPO), the Beaver Valley event indicates that this problem
still exists.
Licensees and applicants may wish to contact BBE to obtain ad- ditional information regarding this problem and appropriate corrective actions.
Failure of a circuit breaker to fully close on demand, inadvertent closure of
a circuit breaker, or loose or missing closing spring charging motor mounting
bolts could result in a circuit breaker not performing its intended function.
This, in turn, could result in the loss of a power supply (such as a vital bus
or a diesel generator).
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate regional office or this office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jack Ramsey, NRR
(301) 492-9081 Attachment:
List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- OGCB:DOEA:NRR
- PPMB:ARM
- C/OGCB:DOEA: NRR
/
JERamsey
TechEd
CHBerlinger
C
s
\\
08/04/87
08/06/87
08/21/87
08,?87 x
IN 87-XX
August, 1987 breaker preventive maintenance program, which the licensee believes to be in
accordance with the vendor's recommendations, did not detect this problem. The
licensee believes the root cause of the problem to be insufficient torquing of
the charging motor mounting bolts by the vendor.
Discussion:
With regard to the repeated closing and opening of the breaker, this problem
was also reported to the NRC in accordance with the reporting requirements of
10 CFR 50.55(e) by Philadelphia Electric Company, for Limerick Unit 1, in 1983.
The circuit breakers involved were returned to BBE for analysis, and BBE
transmitted its findings to the NRC in a letter dated April 20, 1983.
BBE
stated that the repeated closing and opening of the circuit breaker can be
corrected by the addition of a light spring to the close latch in the circuit
breaker operating mechanism. The addition of this spring forces the clearances
in the close latch and associated linkages to be taken up in one direction.
This reduces the shock from the latch and linkages so that when the closing
springs drive the close latch roller, which is part of the cam assembly, at the
end of the charging cycle, the latch is held and does not slip. BBE also
stated that, depending upon the year of manufacture, circuit breakers may or
may not have been originally supplied with this spring.
BBE recommended that
these springs be installed in circuit breakers that were not originally sup- plied with one.
This problem may also affect BBE Type 7.5HK, 15HK, and 38HK
circuit breakers. Although information regarding this problem has been dis- tributed by BBE and the Institute for Nuclear Power Operations (INPO), the
Beaver Valley event indicates that this problem still exists.
Failure of a circuit breaker to fully close on demand, inadvertent closure of a
circuit breaker, or loose or missing closing spring charging motor mounting
bolts could result in a circuit breaker not performing its intended function.
This, in turn, could result in the loss of a power supply important to safety
(such as a vital bus or a diesel generator).
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate regional office or this office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jack Ramsey, NRR
(301) 492-9081 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- OGCB: DOEA:NRR
- PPMB:ARM
C/OGCB: DOEA:kRR
D/DOEA:NRR
JERamsey
TechEd
CHBerlinger S f't
CERossi
08/04/87
08/06/87
08/ I /87 Fro0t
08/ /87
IN 87-XX
August, 1987 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate regional office or this office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jack Ramsey, NRR
(301) 492-9081 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- OGCB:DOEA:NRR
PPMB:ARM I
JERamsey
TechEdiW
08/04/87
08/o6/87 C/OGCB:DOEA:NRR
CHBerlinger
08/ /87 D/DOEA:NRR
CERossi
08/ /87
IN 87-XX
August, 1987 This reduces the shock from the latch and linkages so that when the close latch
roller, which is part of the cam assembly, is driven by the closing springs at
the end of the charging cycle against the close latch, the latch is held and
does not slip. BBE also stated that, depending upon the year of manufacture, circuit breakers may or may not have been originally supplied with this light
spring. BBE recommended that light springs be installed in circuit breakers
that were not originally supplied with one. This problem may also affect BBE
Type 7.5HK, 15HK, and 38HK circuit breakers.
Another potential problem with BBE circuit breakers occurred at River Bend and
was reported in Licensee Event Report (LER)87-004, dated March 6, 1987. On
February 6, 1987, with the unit at full power, the Division I Diesel Generator
4.16KV output circuit breaker (Gould-Brown Boveri Type 5HK) failed to close
during the performance of a weekly surveillance test.
The licensees' inspec- tion of the output circuit breaker revealed that a mounting bolt had fallen out
of the closing spring charging motor, rendering the motor inoperable.
Further
investigation revealed several other circuit breakers that contained loose or
missing charging motor mounting bolts.
The licensee also stated that their
circuit breaker preventive maintenance program, which they believe is in
accordance with the vendor's recommendations, did not detect this problem.
Discussion:
Failure of a circuit breaker to fully close on demand, inadvertent closure of a
circuit breaker, or loose or missing closing spring charging motor mounting
bolts could result in a circuit breaker not performing its intended function.
This could result in the loss of a power supply important to safety (such as a
vital bus or a diesel generator).
Although information regarding the installation of a light spring has been
distributed by BBE and INPO, the occurrence of this event indicates that this
problem still exists.
Therefore, it is recommended that licensees and appli- cants take steps to assure that the light spring is present in BBE circuit
breakers, and that the closing spring charging motor mounting bolts are not
loose or missing.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate regional office or this office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jack Ramsey, NRR
(301) 492-9081 Attachment: List of Recently Issued NRC Information Notices
OGCO
ON
E RR
PPMB:ARM
C/OGCB:DOEA:NRR
D/DOEA:NRR
JERamsey
TechEd
CHBerlinger
CERossi
08/4 /87
08/ /87
08/ /87
08/ /87