Information Notice 1996-43, Failures of General Electric Magne-Blast Circuit Breakers
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
August 2, 1996
FAILURES OF GENERAL ELECTRIC MAGNE-BLAST
CIRCUIT BREAKERS
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to recent failures of General Electric (GE) 4.16 kV
Magne-Blast circuit breakers at the Dresden Nuclear Power Station. Unit 3 (Dresden 3), caused by hardened grease and failures of Magne-Blast breakers to
latch closed at the Salem Nuclear Generating Station (Salem) and the Maine
Yankee Atomic Power Plant (Maine Yankee). The NRC staff is preparing a
separate information notice to discuss failures related to refurbishment
practices, including zinc plating of surfaces and recently discovered broken
lock washers at Salem. 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 are not NRC requirements: therefore, no specific
action or written response is required.
Description of Circumstances
Failure Due to Hardened Grease
On June 11.
1996. at Dresden 3. a 4.16-kV GE Magne-Blast circuit breaker that
supplies power to a low-pressure coolant injection pump motor failed to open
on demand from the control room following a surveillance run of the pump.
Examination of the failed breaker showed hardened grease in the breaker
mechanism.
In subsequent testing of four similar spare breakers. all tripped at required
low voltage conditions.
However, two of the breakers showed the potential for
unreliable operation because their trip latch roller bearings did not freely
rotate.
The cause was hardened grease.
During bench testing of breakers
pulled from the cubicles to date, two additional breakers failed to trip on
required low voltage. Both breakers exhibited hardened grease conditions in
trip latch roller bearings.
The licensee identified 23 safety-related breakers in Dresden 3 as susceptible
to this failure mechanism. On June 20, 1996, the licensee initiated a
I ;;cr
6-oL3 O+°o°K
9607310096°
If\\1
IN 96-43 August 2, 1996 shutdown of Dresden 3 and contracted wits GE Nuclear Energy to completely
overhaul each of these 23 breakers and the similar ones in Dresden 2.
Failure to Latch Closed
On January 5. 1996, at Salem, a 4.16-kV GE Magne-Blast circuit breaker that
supplies power to a service water pump motor failed to latch closed on demand
from the control room.
During the subsequent investigation with the breaker
in test position, the breaker failed to latch closed on the seventh attempt
after successfully latching closed six times.
On February 15, 1996. a different service water pump breaker at Salem failed
to latch closed. This breaker had been returned to service after an overhaul
at the GE Apparatus Service Center in Philadelphia.
On September 27, 1993, at Maine Yankee, a 4.16-kV GE Magne-Blast component
cooling water pump breaker failed to latch closed on demand from the control
room. The licensee enabled this breaker to close reliably by replacing the
upper prop spring with a heavier prop spring (of the gold-colored type used as
a lower prop spring).
Discussion
In 1989. during an NRC maintenance team inspection at Dresden, the team found
a lack of lubrication of these same breakers. At that time, the licensee
instituted a preventive maintenance program as a corrective measure.
Subsequent NRC review of that program showed that the licensee had not fully
implemented recommendations of the manufacturer, GE Specialty Breaker Plant.
The GE instruction book applicable to the horizontal-drawout Magne-Blast
circuit breakers used at Dresden (GEI-88771D), a similar book applicable to
vertical-lift breakers used elsewhere (GEK-7320F), and GE Service Advice
Letter (SAL) 354.1. dated August 25, 1995. recommend that these breakers be
lubricated once every 2 years. The licensee, however, had been using a six- year maintenance period and had not maintained (cleaned and lubricated) the
failed breaker for six and a half years. The following factors may have
contributed to the aging and hardening of grease over this protracted
maintenance period:
(1) contamination of grease by an aerosol degreaser
during maintenance in 1989, (2) prevention of the light-weight lubricating oil
applied during the 1989 maintenance from reaching internal bearing surfaces
and refreshing the grease (the licensee had applied a light coating of grease
before applying the oil). (3) premature aging of grease from cubicle heaters.
and (4) presence of fibrous material in the one affected bearing.
In Information Notice 94-54, the NRC staff alerted licensees to failures of
Magne-Blast breakers to latch closed and discussed the recommendation (GE
SAL 352) to add a second prop spring to correct the failure. The staff
pointed out that breakers that are grossly out of adjustment or badly worn may
fail to latch closed even with the addition of a second prop spring.
The Salem licensee and GE jointly used high-speed digital video equipment to
learn that the failure mechanism is complex and that the prop-to-prop pin
IN 96-43 August 2. 1996 motion is influenced by the opening and closing spring energy, prop spring
force, and primary contact assembly wipe or rebound. The timing of the
rebound of the prop pin (if it is present) relative to the prop reset motion
is critical to reliable operation. If the prop pin impacts the tip of the
prop. it may reverse the prop motion. The breaker will fail to latch if the
prop does not have sufficient time to recover to a position under the pin
before the pin falls. The impact also may cause the tips of the prop to
become chipped or flattened.
In agreement with GE. the Salem licensee believes the prop pin may fail to
achieve the required position because of (1)
the age and wear of the breaker,
(2) misalignment of the prop mechanism, (3) errors that may be introduced in
the alignment of the operating mechanism causing the prop and or articulated
mechanism to twist. (4) misalignment of the stationary cubicle in which the
breaker operates, and (5) opening spring adjustment. The cause of any
particular failure to latch may have to be determined on an individual basis.
This problem affects vertical-lift Magne-Blast circuit breakers with ML-13 mechanisms that have close-latch ratings of 77 kA or above (high momentary
ratings).
The Salem licensee concluded that the following symptoms are indicative of the
conditions present during the high-speed prop reset action that could result
in failure of the breaker to latch closed:
- The prop stop pin is not in the fully forward position in the
inspection window when the breaker is closed.
- The tips of the prop are chipped or flattened.
(The prop tips may
be viewed through both inspection holes.)
- The breaker has a history of intermittently failing to latch closed.
- If the arcing contacts have overstroked, the tips of the arcing
contacts will probably be damaged by their impact on the dividers in
the stationary arcing contacts, and the buffer blocks may be
cracked.
- Prop wipe is unequal. indicating prop or prop pin twist.
In agreement with GE. the corrective action taken at Salem was to raise the
preload on the opening spring to slow down the closing action, thus allowing
more time for the prop to get into position. However, this approach is
limited by the minimum speed that must be achieved by the moving contacts to
maintain the high momentary rating.
GE Philadelphia Operations is pursuing an alternative solution: (1) replacing
the second prop spring with a heavier one, currently under development, (2)
installing a second prop stop to restrict the prop movement on the left-hand
side, and (3) adjusting the wipe on the main contacts.
When testing is
complete, GE plans to issue a SAL on this subject.
August 2, 1996 Related Generic Communications
1.Bulletin 74-09, "Deficiency in General Electric Model 4KV Magne-Blast
Breakers," August 6, 1974.
2. Information Notice 84-29. "General Electric Magne-Blast Circuit Breaker
Problems," April 17, 1984.
3. Information Notice 90-41, "Potential Failure of General Electric
Magne-Blast Circuit Breakers and AK Circuit Breakers," June 12, 1990.
4. Information Notice 93-26, "Grease Solidification Causes Molded Case
Circuit Breaker Failure To Close," April 7, 1993.
5. Information Notice 93-91, "Misadjustment Between General Electric 4.16-KV
Circuit Breakers and Their Associated Cubicles," December 3. 1993.
6. Information Notice 94-02, "Inoperability of General Electric Magne-Blast
Breaker Because of Misalignment of Close-Latch Spring," January 7. 1994.
7. Information Notice 94-54, "Failures of General Electric Magne-Blast
Circuit Breakers To Latch Closed," August 1, 1994.
8. Information Notice 95-22, "Hardened or Contaminated Lubricants Cause
Metal-Clad Circuit Breaker Failure," April 21, 1995.
This information notice requires no specific action or written response.
If
you have any questions about the information herein, please contact one of the
technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
Brian K. Grimes, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: D. Skeen. NRR
K. Naidu, NRR
(301) 415-1174
(301) 415-2980
E-mail: dls@nrc.gov
E-mail: krn@nrc.gov
A. Pal, NRR
J. Shannon, Region I
(301) 415-2760
(610) 337-5132 E-mail:
anp@nrc.gov
E-mail: jmsl@nrc.gov
Attachment:
List of Recently Issued NRC Information Notices
, #k-
Attachment
August 2, 1996 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
96-42
96-41
96-40
96-09.
Supp. 1
96-39
Unexpected Opening of
Multiple Safety Relief
Valves
Effects of a Decreuse in
Feedwater Temperature on
Nuclear Instrumentation
Deficiencies in Material
Dedication and Procurement
Practices and in Audits of
Vendors
Damage in Foreign Steam
Generator Internals
Estimates of Decay Heat
Using ANS 5.1 Decay Heat
Standard May Vary Signi- ficantly
Results of Steam Generator
Tube Examinations
Inaccurate Reactor Water
Level Indication and Inad- vertent Draindown During
Shutdown
Degradation of Cooling
Water Systems Due to Icing
Failure of Safety Systems
on Self-Shielded Irradia- tors Because of Inadequate
Maintenance and Training
08/05/96
07/26/96
07/25/96
07/10/96
07/05/96
06/21/96
06/18/96
06/12/96
06/11/96
Al 1 holders of OLs or CPs
for nuclear power reactors
All holders of OLs or CPs
for pressurized water
reactors
All holders of OLs or CPs
for nuclear power reactors
All holders of OLs or CPs
for pressurized-water
reactors
All holders of OLs or CPs
for nuclear power reactors
All holders of OLs or CPs
for pressurized water
reactors
All pressurized water
reactor facilities holding
an operating license or a
construction permit
All holders of OLs or CPs
for nuclear power reactors
All U.S. Nuclear Regulatory
Commission irradiator
licensees and vendors
96-38
96-37
96-36
96-35 OL = Operating License
CP = Construction Permit
August 2. 1996 Related Generic Communications
1.Bulletin 74-09, "Deficiency in General Electric Model 4KV Magne-Blast
Breakers," August 6, 1974.
Problems," April 17, 1984.
"General Electric Magne-Blast Circuit Breaker
3. Information Notice 90-41, "Potential Failure of General Electric
Magne-Blast Circuit Breakers and AK Circuit Breakers." June 12. 1990.
4. Information Notice 93-26. "Grease Solidification Causes Molded Case
Circuit Breaker Failure To Close," April 7. 1993.
5. Information Notice 93-91, "Misadjustment Between General Electric 4.16-KV
Circuit Breakers and Their Associated Cubicles." December 3. 1993.
6. Information Notice 94-02, "Inoperability of General Electric Magne-Blast
Breaker Because of Misalignment of Close-Latch Spring." January 7. 1994.
7. Information Notice 94-54, "Failures of General Electric Magne-Blast
Circuit Breakers To Latch Closed," August 1. 1994.
8. Information Notice 95-22, "Hardened or Contaminated Lubricants Cause
Metal-Clad Circuit Breaker Failure," April 21, 1995.
This information notice requires no specific action or written response.
If
you have any questions about the information herein, please contact one of the
technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
Ofigid signed by Brian K.
Grimes
Brian K. Grimes. Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
D. Skeen. NRR
K. Naidu. NRR
(301) 415-1174
(301) 415-2980
E-mail:
dls@nrc.gov
E-mail: krn@nrc.gov
Technical contacts:
A. Pal. NRR
(301) 415-2760
E-mail:
anp@nrc.gov
Tech Editor has reviewed and concurred on
CONCURRENCES
At1tahmpnt.
Licst nf Rprpntlv Tssued NRC
J. Shannon, Region I
(610) 337-5132 E-mail:
jmsl@nrc.gov
07/23/96
- SEE PREVIOUS
Information Notices
A
I --
- .
1
-
-
-
.
. --
9 .
, -,
- -
v .
w_ _ _
.
.-
-
. _
a
OFC
PECB:DRPM
C. EELB:DE
C, PSIB:DISP
DIR.
NAME
VHodge*
JCalvo*
RGallo*
Bi
DATE
07/26/96
07/26/96
07/29/96
07/V(/96 _
I
document: 96-43.IN
IN 96- July
, 1996 Related Generic Communications
1.Bulletin 74-09, "Deficiency in General Electric Model 4KV Magne-Blast
Breakers." August 6, 1974.
2. Information Notice 84-29, "General Electric Magne-Blast Circuit Breaker
Problems," April 17, 1984.
3. Information
Magne-Blast
Notice 90-41, "Potential Failure of General Electric
Circuit Breakers and AK Circuit Breakers," June 12. 1990.
4. Information Notice 93-26. "Grease Solidification Causes Molded Case
Circuit Breaker Failure To Close." April 7, 1993.
5. Information Notice 93-91, "Misadjustment Between General Electric 4.16-KV
Circuit Breakers and Their Associated Cubicles," December 3, 1993.
6. Information Notice 94-02, "Inoperability of General Electric Magne-Blast
Breaker Because of Misalignment of Close-Latch Spring," January 7. 1994.
Circuit Breakers To Latch
"Failures of General Electric Magne-Blast
Closed," August 1. 1994.
8. Information Notice 95-22, "Hardened or Contaminated Lubricants Cause
Metal-Clad Circuit Breaker Failure," April 21, 1995.
This information notice requires no specific action or written response. If
you have any questions about the information herein, please contact one of the
technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
Brian K. Grimes, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
D. Skeen, NRR
(301) 415-1174 E-mail: dls@nrc.gov
K. Naidu, NRR
(301) 415-2980
E-mail:
krn@nrc.gov
A. Pal. NRR
(301) 415-2760
E-mail: anp@nrc.gov
J. Shannon, Region I
(610) 337-5132 E-mail: jmsl@nrc.gov
A++ Mt-kA^M~nn+ -
I jet nf Poinrntlv TciIja
NRC
Wnformatinn Nntirces
M6AUI
IlII K;
IL-
m
&-I J%,
WIII
J
...
SU
-,\\
s.sv
1
9-
-
_
___
OFC
PECB:DRPM
C, EELB:DE
C, PSIB:DISP
DIR, DRPM
NiME
VHodge
JCalvo
RGallo
BGrimes
DATE
07/ /96
07/ /96
07/ /96
07/ /96
-
_ - -
_ _
_____%
___L__
met
di..
aocument:
- Wver \\gdYUI db L. I II
14aX.L)
IN 96-XX
July xx, 1996 This information notice requires no specific action or written response. If
you have any questions about the information herein, please contact one of the
technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
Brian Grimes, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
D. Skeen, NRR
(301) 415-1174 E-mail: dls@nrc.gov
K. Naidu, NRR
(301) 415-2980
E-mail: krn@nrc.gov
A. Pal, NRR
(301) 415-2760
E-mail: anp~nrc.gov
J. Shannon, Region I
(610) 337-5132 E-mail: jmsl@nrc.gov
Att2rhmant*
list nf Rpnentlv Issued NRC Information Notices
f>~l
b 4 '~ ll.
S l
> v ~. w
, _ _ _ _
.
.
.
.
.
.
. ....................
_-_J_...
_ _
OFC
PECB:DRPM A
CE EELB:DE W C f
fIBeDIR
DRPM
NAME
VHodge
JCalvo
I
BGrimes
DATE
0
07/61Z/96
1 0
/96 A
-
_ _ %0
7
/
document: g:\\vern\\maigoui7.inf
Oldso