United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 83-84: Cracked and Broken Piston Rods in Brown Bovery Electric Type 5HK Breakers

                                                            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 



8312120093 
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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
.

                                                          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
.

                                                          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
.

                                                          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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Page Last Reviewed/Updated Tuesday, November 12, 2013