United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-40: Deficiencies in Primary Containment Electrical Penetration Assemblies

                                                            SSINS No.: 6835 
                                                            IN 62-40 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 

                             September 22, 1982 

Information Notice No. 82-40:   DEFICIENCIES IN PRIMARY CONTAINMENT 
                                   ELECTRICAL PENETRATION ASSEMBLIES 

Addressees: 

All nuclear power plant facilities holding an operating license (OL) or 
construction permit (CP). 

Purpose:  

This information notice is provided as an early notification of a 
potentially significant problem pertaining to electrical connections in 
electrical penetration assemblies supplied by the Bunker Ramo Corporation of 
Chatsworth, California. The potential safety significance and related 
generic implications of this problem as it applies to operating plants and 
plants under construction are still under review by the Nuclear Regulatory 
Commission (NRC) staff. If the NRC evaluation so indicates, further licensee
action may be requested. In the interim, we expect the recipients of this 
Information Notice to review the information herein for applicability to 
their facilities and to take appropriate actions. No specific action or 
response is required at this time. 

Description of Circumstances: 

Several deficiencies of the containment's electrical penetration assemblies 
supplied by Bunker Ramo, have been identified. A summary of these 
deficiencies is provided below: 

1.   On January 15, 1979, Consumer Power Company submitted 10 CFR 50.55(e) 
     report No. 78-12 for the Midland nuclear facility identifying 
     deficiencies associated with #10 AWG and smaller wire terminations 
     located in the inboard terminal boxes of Bunker Ramo penetration 
     assemblies. The deficiencies identified included improper lug crimps, 
     incorrect lug types, and loose connections on terminal blocks. These 
     deficiencies were attributed, in part, to an inexperienced employee at 
     Bunker Ramo. 

2.   On March 26, 1980, Union Electric Company submitted 10 CFR 50.55(e) 
     report No. 80-03 for the Callaway nuclear facility identifying 
     deficiencies associated with electrical penetration assemblies supplied
     by Bunker Ramo. The deficiencies included improperly crimped lugs and 
     improperly identified penetration cables. During hand-pull tests at 
     least 38 wires separated from their lugs. It was reported that this 
     deficiency resulted when Bunker Ramo overcrimped and undercrimped lugs.


8208790232 
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                                                      IN 82-40  
                                                      September 22, 1982  
                                                      Page 2 of 3 

3.   On June 12, 1980, the NRC was informed by Standardized Nuclear Unit 
     Power Plant Systems (SNUPPS) that additional inspections at the Wolf 
     Creek nuclear facility identified further concerns regarding the 
     quality and integrity of Bunker Ramo electrical penetration 
     terminations. Deficiencies identified at the Wolf Creek facility 
     included improperly crimped lugs and incorrectly sized lugs.  

4.   On October 2, 1980, Commonwealth Edison submitted 10 CFR 50.55(e) 
     report No. 80-02 for the LaSalle County Station Unit 2 facility 
     identifying cracked or missing insulation (exposing bare copper) on 
     small-diameter conductors as they enter/exit the epoxy module portion 
     of the Bunker Ramo electrical penetrations. The report stated, in part, 
     "The cracking was determined to have resulted from stress points in the 
     insulation created by a mechanical bond between the potting compound 
     (used to form the over-mold portion of the module) and the insulation. 
     Movement of the conductors entering or exiting the modules produced 
     cracks along the stress points." Subsequent to this report, LaSalle 
     experienced failures while testing several Bunker Ramo fabricated 
     in-line butt splices in modules that had been installed. 

5.   On March 31, 1982, the NRC was advised through a 10 CFR 21 report that 
     deficiencies have been identified in Bunker Ramo electrical 
     penetrations installed at the Midland nuclear facility. The 
     deficiencies involve #2, #6, #8, #10, #14, and #16 AWG splices and 
     cracks in the insulation of some conductors as they emerge from certain 
     types of modules. The deficiencies were reported to have occurred when 
     site personnel moved cables to inspect for rodent damage. 

6.   On April 8, 1982, Consumers Power Company submitted 10 CFR 50.55(e) 
     report No. 82-02 for the Midland nuclear facility identifying 
     deficiencies in Bunker Ramo electrical penetrations. The identified 
     deficiencies include cracks in conductor insulation at the 
     conductor-module interface (resulting in some expo$ure of the module's 
     copper conductors) and inadequately crimped butt splices (resulting in 
     several #2 AWG butt splices being pulled apart). These deficiencies 
     were observed in installed electrical penetrations. In addition, 
     similar deficiencies were observed in crated electrical penetrations 
     and spare module assemblies stored in warehouse facilities. The cracked 
     insulation was reported to have been probably caused by a 
     chemical/mechanical reaction between the module materials, mechanical 
     stresses resulting from the module design, and a lack of explicit 
     handling/packing instructions reflecting the frailty of the electrical 
     penetrations/modules. The inadequately crimped butt splices were 
     reportedly caused by a breakdown in the fabrication/design of the 
     module assemblies. 

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                                                      IN 82-40  
                                                      September  22, 1982 
                                                      Page 3 of 3 

The above deficiencies have all been identified as existing in Bunker Ramo 
electrical penetrations utilizing a hard epoxy module design. Specifically, 
the study concluded that the over- and undercrimping problem was, in part, 
caused by using different sized wire cable for the same in-line butt splice 
connector. This resulted in the numerous over- and undercrimping connections
(e. g., Midland and LaSalle Station plants) found in splices supplied by 
Bunker Ramo. It appears that if wirecrimping force adjustments had been made
to accommodate the different wire sizes, as discussed above, the over- and 
undercrimping problem would have been significantly alleviated. 

The loose terminations and poor crimping of ring nut connectors found in the
terminal boxes supplied by Bunker Ramo appears to have been attributed to 
poor quality control and assembly line techniques at the fabrication 
facility. 

The problems of incorrect lug sizes and improper crimping may also exist in 
the earlier Bunker Ramo penetration assembly design which utilizes a soft 
epoxy module. 

If you have any questions regarding these matters, please contact the 
administrator of the appropriate Regional Office or this office. 



                              Edward L. Jordan, Director 
                              Division of Engineering and 
                                Quality Assurance 
                              Office of Inspection and Enforcement 

Technical Contact   V. D. Thomas 
                    301-492-4967 

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