Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 83-84
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
December 30, 1983
Information Notice No. 83-84: CRACKED AND BROKEN PISTON RODS IN BROWN
BOVERY ELECTRIC TYPE 5HK BREAKERS
Addressees:
All holders of a nuclear power reactor operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as notification of a potentially
significant problem pertaining to Brown Bovery Electric (BBE) type 5HK
250/350, 1200/2000 ampere circuit breakers. Addressees are expected to
review the information for applicability to their facilities. No specific
action or response is required at this time.
Description of Circumstances:
On March 21, 1983, Detroit Edison notified the NRC under the provisions of
10 CFR 50.55(e) of a potential problem with BBE 5HK 4160 volt breaker puffer
piston rods at the Fermi 2 nuclear plant. The puffer piston connecting rods
developed cracks and one shaft failed. The manufacturer's part number is
193642B. The cracking and failure occurred at the hole in the shaft where
the linkage is connected by a pin. These breakers were manufactured in 1973.
A total of five breakers were affected at the Fermi 2 site.
On September 12, 1983, Detroit Edison advised an NRC inspector that during a
receiving inspection at the Fermi plant, spare puffer piston connecting rods
were found to be defective. They were all returned to the vendor. BBE
informed the NRC on November 29, 1983 that the damage to these puffer piston
connecting rods were a result of shipping problems and were riot related to
the manufacturing process.
On October 12, 1983, BBE provided the NRC with an Interim Report pertaining
to the 5HK breaker puffer piston connecting rod problem. The report
indicated that at a Southern California Edison (SCE) non-nuclear plant eight
puffer piston connecting rods were found to be broken.
Puffer pistons in the BBE 5HK breakers perform two functions. For low
current interruptions the puffer is needed to assist the magnetic forces to
move the
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IN 83-84
December 30, 1983
Page 2 of 2
arc into the interrupting chamber. The arc may not be extinguished if the
puffer piston fails. The other function performed by the puffer piston is to
provide a pneumatic cushion which reduces the shock forces imposed on the
mechanism and current carrying parts upon opening. A failure of the puffer
piston could reduce the number of operations before maintenance on the
breaker would be necessary.
BBE indicated that no breaker failed because of a broken puffer piston rod,
however, the breaker's capability to interrupt at low current may be
impaired.
BBE subjected broken piston rods to failure analysis including microscopic
analysis of the failed area and found that failed parts were limited to
those made with the material identified as Zytel 101 (Nylon 6/6). Since
1980, the parts have been manufactured with a toughened and reinforced
material called "Nylatil." No problems have been reported on Nylatil
material parts.
Based on the test results and presently available information, BBE
recommends inspecting for cracked or broken puffer piston rods at normal
maintenance intervals and replacing the puffer piston assembly if this
condition is found. It should be noted that the nozzle of the puffer piston
must be removed to inspect the rod properly.
Attached is a list provided by BBE of 5HK circuit breakers that they
supplied for use in Class 1E applications at nuclear power plants, and which
may be affected. Since breakers can also be obtained from intermediate
sources, the list may not be complete. It is suggested that licensees
evaluate their equipment lists to determine if BBE 5HK breakers are used in
safety-related applications in their plant. Inspection of circuit breakers
with manufacturing dates of 1981 or later for cracking or breakage of puffer
piston rods should not be necessary.
If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this Office.
Edward L. Jordan Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: W. Laudan, IE
(301) 492-9759
Attachments:
1. List of 5HK Breaker Customers
2. List of Recently Issued IE Information Notices
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Attachment 1
IN 83-84
December 30, 1983
Page 1 of 3
BBE TYPE 5HK BREAKER CUSTOMERS
CUSTOMER BBE SALES ORDER DATE OF MANUFACTURE
CEI
Perry 1&2 51958 8/78, 9/78,
10/78
CFE
Laguna Verde 53462 11/74 - 1/80
CP&L
Brunswick 1 54792 10/81
Brunswick 2 47219 11/71 - 8/72
49839 3/74 - 3/79
Cincinnati G&E
Zimmer 51828 6/77 - 11/77
Commonwealth Edison
LaSalle County 1&2 50080 10/75 - 12/75
52612 4/78, 5/78
Zion 1&2 45122 5/70 - 2/71
Consumers Power
Midland 1&2 50382 4/75 - 9/75
9/75 - 6/76
8/75 - 9/75
Detroit Edison
Fermi 2 47196 12/73 - 9/74
Duke
Catawba 1 & 2 50465 4/78 - 4/79
McGuire 1 & 2 48560 9/72 - 11/74
Oconee 3 44349 8/69 - 8/71
Duquesne Light Co.
Beaver Valley 1&2 46690 8/71 - 8/78
Florida Power Corp
Crystal River 3 46256 11/70
Georgia Power Company
Vogtle 1 51903 9/81 - 3/82
Vogtle 2 51904 7/81 - 2/83
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Attachment 1
IN 83-84
December 30, 1983
Page 2 of 3
BBE TYPE 5HK BREAKER CUSTOMERS CUSTOMER
CUSTOMER BBE SALES ORDER DATE OF MANUFACTURE
Gulf States Utilities
River Bend 1&2 51126 11/80 - 3/83
51128 10/80 - 4/82
Indiana Michigan Electric Co.
Cook 1 44322 8/71 - 3/72
Cook 2 53372 5/79
Mississippi Power & Light
Grand Gulf 1&2 50469 1/76 - 5/77
Northern States Power
Prairie Island 1&2 44477 2/70 - 10/71
PE
Limerick 1&2 47651 3/77 - 5/77
PSE&G
Hope Creek 1&2 52260 10/79 - 1/90
Psi
Marble Hill 2 52661 11/80 - 8/82
PSNH
Seabrook 1&2 50750 1/77 - 8/77
Portland General Electric
Trojan 47354 2/73
Sacramento Municipal Utility
District
Rancho Seco 1
45966 5/71
South Texas
Project 1 52769 10/78
Project 2 52914 5/79 - 12/79
Southern California Edison
San Onofre 2&3 50395 3/76 - 4/76
Taiwan
Kuo Sheng/Unit 1&2 50735 5/77 - 12/76,
11/75 - 12/75,
3/76
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Attachment 1
IN 83-84
December 30, 1983
Page 3 of 3
BBE TYPE 5HK BREAKER CUSTOMERS
CUSTOMER BBE SALES ORDER DATE OF MANUFACTURE
VEPCO
North Anna 2 48709 9/76, 10/76
WPPSS
WNP 1&2 51659 3/78 - 1/79
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