Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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
Attachment:
List of Recently Issued IE Information Notices
