ML20057E938
| ML20057E938 | |
| Person / Time | |
|---|---|
| Issue date: | 10/06/1993 |
| From: | Marcus G Office of Nuclear Reactor Regulation |
| To: | Recasha Mitchell GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 9310130389 | |
| Download: ML20057E938 (4) | |
Text
'
October 6, 1993 1
'./
Mr. Robert Mitchell Safety Evaluation Program, Project Manager General Electric Nuclear Energy 175 Curtner Avenue San Jose, CA 95125
Dear Mr. Mitchell:
SUBJECT:
INFORMATION NOTICE REGARDING GENERAL ELECTRIC MAGNE-BLAST BREAKER The U.S. Nuclear Regulatory Commission is planning to issue an information notice (IN) discussing the inoperability of General Electric (GE) magne-blast breakers which occurred at the Palo Verde Nuclear Generating Station.
Mr. Kamal Naidu has discussed the technical issue regarding this event with you.
Please review the draft IN to ensure that the technical information is correct and return any comments you may have as soon as possible.
Your cooperation is appreciated.
If no comments are received by October 20, 1993, we will assume the technical information in the notice is correct.
If you have any questions regarding this issue, please phone Peter Wen of my staff at (301) 504-2832.
Original signed by Richard J. Kiessel for Gail H. Marcus, Chief Generic Communications Branch Division of Operating Reactor Support Office of Nuclear Reactor Regulation
Enclosure:
Draft Information Notice DISTRIBUTION Central File BKGrimes DORS R/F GHMarcus AChaffee CICrimes SHWeiss PDR HWong, RV JSloan, (SRI-Palo Verde)
PCWen 0GCB R/F PCWen R/F
- SEE PREVIOUS CONCURRENCE OFFICE
+0GCB:00RS
- C:RVIB:DRI C:0GCB/ DORS
,./
L GHMarcusk NAME PCWen/vsb LJNorrholm DATE 10/06/93 10/06/93 10///93 hI g
DOCUMENT NAME:
L1R'iOGE. WEN 3
h, hO T.f $
> t Ja I#
9310130389 931006 e
October 6, 1993 Mr. Robert Mitchell Safety Evaluation Program, Project Manager General Electric Nuclear Energy 175 Curtner Avenue San Jose, CA 95125
Dear Mr. Mitchell:
SUBJECT:
INFORMATION NOTICE REGARDING GENERAL ELECTRIC MAGNE-BLAST BREAKER The U.S. Nuclear Regulatory Commission is planning tc issue an inicrmation notice (IN) discussing the inoperability of General Electric (GE) magne-blast breakers which occurred at the Palo Verde Nuclear Generating Station.
Mr. Kamal Naidu has discussed the technical issue regarding this event with you.
Please review the draft IN to ensure that the technical information is correct and return any comments you may have as soon as possible.
Your cooperation is appreciated.
If no comments are received by October 20, 1993, we will assume the technical information in the notice is correct.
If you have any questions regarding this issue, please phone Peter Wen of my staff at (301) 504-2832.
Original signed by Richard J. Kiessel for Gail H. Marcus, Chief Generic Communications Branch Division of Operating Reactor Support Office of Nuclear Reactor Regulation
Enclosure:
Draft Information Notice DISTRIBUTION Central File BKGrimes DORS R/F GHMarcus AChaffee CIGrimes SHWeiss PDR HWong, RV JSloan, (SRI-Palo Verde)
PCWen 0GCB R/F PCWen R/F
- SEE PREVIOUS CONCURRENCE OFFICE
- 0GCB: DORS
- C:RVIB:DRI C:0GCB/ DORS L
//
NAME PCWen/vsb LJNorrholm GHMarcus khY
DATE 10/06/93 10/06/93 10/t6/93 J DOCUMENI NAME:
LlRTOGE. WEN
- - - ~ - - - - - -
DRhPT UNITED STATES NUCLEAR REGULATORY COMMUNICATION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 October xx, 1993 NRC INFORMATION NOTICE 93-xx: INOPERABILITY OF GENERAL ELECTRIC MAGNE-BLAST BREAKER BECAUSE OF MISALIGNMENT OF CLOSE-LATCH SPRING 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 that a misalignment of the close-latch reset spring (tension style) in 4.16-kV General Electric (GE) Magne-Blast circuit breakers could prevent the breaker from closing on demand.
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 On April 7,1993, the Arizona Public Service Company, licensee for the Palo Verde Nuclear Generating Station, notified the NRC that a safety-related 4.16-kV GE Magne-Blast breaker (Model AM-4.16-250-9,1200-ampere breaker with ML-13 mechanism) was found inoperable with the closing springs discharged.
The inoperability was caused by misalignment of the close-latch reset spring.
This misalignment resulted in the coils of the spring catching on the close-latch monitoring switch mounting plate.
This prevented the close-latch monitoring switch from closing and prevented the charging motor from recharging the closing springs, which rendered the breaker inoperable.
The condition was identified by an auxiliary operator who noticed that the white control power / closing springs charged lamp was not illuminated on the front of the breaker cubicle.
There was no indication of this problem in the control room.
Further details can be found in NRC Inspection Report 50-528; 50-529; 50-530/93-11.
i
IN 93-XX October xx, 1993 Page 2 of 2 DISCUSSION GE Magne-Blast breakers are used in many safety-related circuits throughout the nuclear industry.
At Palo Verde, these breakers are used for numerous safety-related pumps (i.e., high-pressure safety injection, low-pressure safety injection, and containment spray) and in safety-related load centers.
While this condition occurred in a 4.16-kV breaker, all GE Magne-Blast breakers equipped with the ML-13 mechanism having the tension style close-latch spring may be susceptible to this problem.
There are two different designs for the close-latch spring in the GE Magne-Blast breakers. The design that caused the problem was the tension-style spring that is positioned beside the close-latch monitoring switch.
- Recently, GE replaced this spring with a torsion-style spring, which surrounds the close-latch shaft and effectively prevents the spring from catching on the mounting plate. GE considers this modification to be a design enhancement and has not issued a service advisory letter or instruction on this subject.
The failed condition described above may not be evident if a breaker racking operation is performed before the close-latch spring is inspected.
The vibration associated with the racking operation may be sufficient to free the spring from the close-latch monitoring switch mounting plate.
However, during subsequent breaker operation, the spring coils may catch and render the j
breaker inoperable.
No specific action or written response is required by this information notice.
If you have any questions regarding this matter, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director Division of Operating Reactor Support Office of Nuclear Reactor Reguiation Technical contacts:
J. Frederick Ringwald, RIV (316) 364-8653 Kamalakar. R. Naidu, NRR (301) 504-2980
Attachment:
List of Recently Issued NRC Information Notices