United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 88-27: Deficient Electrical Terminations Identified in Safety-Related Components

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                             WASHINGTON, D.C.  20555

                                  May 18, 1988

                                   IDENTIFIED IN SAFETY-RELATED COMPONENTS


All holders of operating licenses or construction permits for nuclear power 


This information notice is being provided to alert addressees of deficiencies 
identified in electrical terminations in safety-related components.  It is ex-
pected 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 do not constitute 
NRC requirements; therefore, no specific action or written response is 

Description of Circumstances:

The Nuclear Regulatory Commission (NRC) has been notified of several recently 
identified deficiencies in electrical terminations in safety-related 
components that, if they had remained uncorrected, would have jeopardized the 
ability of these components to perform their intended safety function.  These 
deficiencies were identified at River Bend Station, Unit 1; Shoreham Nuclear 
Power Station; Vermont Yankee Nuclear Power Station; and Oyster Creek, Unit 1.

River Bend Station, Unit 1

On January 19, 1988, the Gulf States Utility Company (GSU) submitted a 
notification to the NRC, pursuant to 10 CFR Part 21, regarding oversized motor 
operator termination lugs in three main steam shutoff valves and two feedwater 
isolation valves.  GSU reported that during functional testing of a main steam 
shutoff valve on December 7, 1987, the valve motor operator experienced a high 
current surge, which tripped its motor overload heater and prevented the valve 
from fully closing.  During GSU's investigation, two motor leads were found 
burned and separated from the lugs.  A third lug was easily pulled from the 
motor lead by GSU personnel after they removed the heat shrink insulation.  
The lugs were found to be oversized for the motor lead conductors.  In 
addition, during maintenance on a feedwater isolation valve, a lug on one 
motor lead was found to be 

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oversized for the conductor and not crimped.  These lugs were manufactured by 
Thomas & Betts.  They were marked "T&B Navy 23-30 E-6" and were sized for use 
with a #5-#6 AWG conductor.  The actual motor leads were #10 AWG stranded 

Further investigation by GSU personnel found that both valves used Limitorque 
SMB-4 motor operators with terminal blocks that had one-quarter-inch diameter 
terminal screws.  The lugs were the correct size for the one-quarter-inch 
screw, but not for the conductor.  All SMB-4 operators used in safety-related 
applications were inspected by the licensee to determine lug size.  Ten SMB-4 
operators were inspected, and five were found with oversized lugs that were 
deemed unreliable by the licensee, although they passed their surveillance 
requirements.  GSU personnel replaced the defective lugs with correctly sized 
lugs.  GSU is also revising its procedures for inspecting Limitorque motor 
operators when they are received to include inspection of lug size on the 
motor leads to prevent recurrence of this condition, since the defective wire 
lugs were contained in valve operators supplied by the Limitorque Corporation 
during the construction of River Bend Station.  

In a separate 10 CFR Part 21 notification dated December 23, 1987, GSU 
reported that several defective terminations were identified in electrical 
heater panels supplied by NUTHERM International, Inc.  The defective wire 
terminations were in heater panel circuits of the fuel storage building 
engineered safety feature charcoal filters.  The deficiency involved improper 
stripping of conductors that resulted in insulation under the termination 
lugs.  This insulation inhibited a good connection and jeopardized the ability 
of the filters to perform their function.  GSU reported that it had notified 
NUTHERM International of the defect.  

Shoreham Nuclear Power Station

On October 19, 1987, the Long Island Lighting Company (LILCO) submitted a 
notification to the NRC pursuant to 10 CFR Part 21 regarding inadequately 
crimped termination lugs discovered at the Shoreham Nuclear Power Station.
The subject lugs, which were manufactured by AMP Special Industries, were 
installed in control wiring in 4160-volt switchgear equipment manufactured by 
the General Electric Company (GE).  The licensee discovered that many of the 
GE-installed termination lugs were inadequately crimped to the control wires 
and, in some cases, the lugs could be removed by hand.  When LILCO personnel 
inspected these lugs in equipment supplied by GE, they found that of 
approximately 1400 lugs installed by GE, 42% had to be replaced.  

GE determined that its personnel had deviated from the crimp process described 
in their installation procedures during the manufacture of the equipment.  
Therefore, the insulation around the control wires was not properly stripped 
before being inserted into the AMP lugs and an AMP crimper was not used as 
required.  GE also determined that this problem was limited to equipment 
supplied to 
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Shoreham and Salem.  GE stated that it had notified both facilities of the 
problem and that its personnel had been requalified on the proper crimping 
procedures to preclude any further similar incidents. 

Vermont Yankee Nuclear Power Station

On September 28, 1987, Vermont Yankee Nuclear Power Station (Vermont Yankee) 
personnel were conducting pre-startup operability tests on the residual heat 
removal (RHR) pumps and core spray pumps.  During the operability tests, the 
"B" RHR pump motor experienced severe arcing problems and was quickly secured, 
preventing damage to the motor windings.  

Vermont Yankee personnel investigated the problem and found that the arcing 
resulted from a failed AMP motor lead to power lead termination lug.  Motor 
lead and power lead termination lugs were subsequently inspected on three 
other RHR pumps and core spray pumps fitted with AMP lugs.  Termination lugs 
manufactured by Thomas & Betts (T&B) that are used on RHR service water pumps 
and station service water pumps also were inspected.  These inspections 
identified evidence of cracking of varying severity on seven AMP motor lead 
termination lugs; however, no cracks were found on power lead terminations.  
Little or no cracking was identified on terminations manufactured by T&B.  The 
AMP motor lead termination lugs were of the ring tongue type, #2 AWG, model 
#35184, manufactured by AMP Special Industries.  The terminations were 
supplied in conjunction with the motors by GE.  

Several of the cracked lugs were discovered by direct visual inspection, while 
the remainder were identified using 10X magnification and/or dye penetrant 
testing.  During inspection of the lugs, it appeared that the manufacturer's 
stamping on the throat of the lug contributed to the observed cracking because 
a shallow "AMP" die stamp was found at the throat section of the lug.  A stamp 
(a numeral 1, 2, or 3) on the opposite side of the throat, believed to be a 
phase indication, was also suspected of being a contributor.  The cracking 
identified on these lugs was ultimately attributed to excessive bending during 
maintenance activities, with the manufacturer's stamping providing 
pre-stressed flaws for crack initiation and propagation.  The small cramped 
work space inside the motor terminal housings, coupled with the rigidity of 
the required Raychem splices, contributed to fatiguing the lugs during 
maintenance activities.  

Oyster Creek, Unit 1

GPU Nuclear Corporation (GPUNC) submitted Licensee Event Report (LER) 
219-87-011, Revision 1, to the NRC on May 4, 1987, regarding deficient 
electrical terminations at Oyster Creek, Unit 1.  GPUNC reported that on 
February 10, 1987, an electrical technician who was verifying proper wiring 
connections inadvertently moved a wiring harness in a control room panel.  
This movement disconnected the "A" feedwater flow rate signal wire and 
initiated a sequence of events that resulted in a 
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turbine trip and an anticipatory scram.  On February 26, 1987, an electrical 
technician, performing an inspection of wire terminations in response to the 
previous event, disturbed a wire that caused the automatic closure of the main 
steam isolation valves.  

The GPUNC investigation determined that the cause of the first event was in-
sufficient procedural controls over wire termination practices.  The wire 
terminations used in the control room panel were compression-type 
terminations, which capture wires under a metal plate compressed by a screw, 
rather than lug-type terminations.  GPUNC personnel found that different size 
wires were used in the same termination and that sometimes the plate in the 
compression terminations was removed when wires were too large to fit under 
the plate.  The GPUNC investigation also found terminations with cracked or 
broken pressure plates, as well as wires that were unlabeled, unterminated, 
and uninsulated.  Furthermore, GPUNC personnel discovered that when new cables 
were pulled to support modification work, existing wire terminations were 
stressed by the new wires that lay on top of the original wiring.  

The second event was attributed to faulty wire installation, either during 
plant construction or during subsequent maintenance.  Inspection of the wire 
termination showed that the screw used to fasten the wire was loose.  Movement 
of this wire caused four relays to deenergize, resulting in automatic closure 
of the main steam isolation valves.  

GPUNC personnel identified and corrected a total of 123 deficient 
terminations, both compression-type and lug-type.  GPUNC has revised its 
Installation Specifications for wire terminations and Quality Assurance 
Procedures for inspecting wire terminations to ensure and verify proper 
electrical terminations.  These revisions will ensure that an adequate 
structural integrity of the termination exists, require that a 
post-modification and maintenance tug test be performed, and eliminate the 
practice of terminating two wires with significant gauge differences in 
compression-type terminations unless it is endorsed by the termination 
manufacturer.  In addition, GPUNC indicated that it was in the process of 
identifying those terminations that are frequently accessed for surveillance 
and maintenance purposes and will install test connections to minimize 
movement and stress on the terminations.  


These examples emphasize the need to carefully monitor the receipt, instal-
lation, and maintenance of safety-related components with respect to their 
cable or wire terminations.  Licensees may wish to review their current 
receipt, installation, and maintenance procedures to assure that proper 
quality controls and measures exist to preclude such events as those discussed 

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No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the 
technical contacts listed below or the Regional Administrator of the 
appropriate regional office.  

                              Charles E. Rossi, Director
                              Division of Operational Events Assessment
                              Office of Nuclear Reactor Regulation

Technical Contacts:  Jaime Guillen, NRR
                     (301) 492-1153

                     Carl S. Schulten, NRR
                     (301) 492-1192 

Attachment:  List of Recently Issued NRC Information Notices
.                                                            Attachment
                                                            IN 88-27 
                                                            May 18, 1988 
                                                            Page 1 of 1

                             LIST OF RECENTLY ISSUED
                            NRC INFORMATION NOTICES 
Information                                  Date of 
Notice No._____Subject_______________________Issuance_______Issued to________

85-35,         Failure of Air Check          5/17/88        All holders of OLs
Supplement 1   Valves to Seat                               or CPs for nuclear
                                                            power reactors. 

88-26          Falsified Pre-Employment      5/16/88        All holders of OLs
               Screening Records                            or CPs for nuclear
                                                            power reactors and
                                                            all major fuel 

88-25          Minimum Edge Distance for     5/16/88        All holders of OLs
               Expansion Anchor Bolts                       or CPs for nuclear
                                                            power reactors. 

88-24          Failures of Air-Operated      5/13/88        All holders of OLs
               Valves Affecting Safety-                     or CPs for nuclear
               Related Systems                              power reactors. 

88-23          Potential for Gas Binding     5/12/88        All holders of OLs
               of High-Pressure Safety                      or CPs for PWRs. 
               Injection Pumps During a 
               Loss-of-Coolant Accident 

88-22          Disposal of Sludge from       5/12/88        All holders of OLs
               Onsite Sewage Treatment                      or CPs for nuclear
               Facilities at Nuclear                        power reactors. 
               Power Stations 

88-21          Inadvertent Criticality       5/9/88         All holders of OLs
               Events at Oskarshamn                         or CPs for nuclear
               and at U.S. Nuclear                          power reactors. 
               Power Plants 

88-20          Unauthorized Individuals      5/5/88         All holders of OLs
               Manipulating Controls and                    or CPs for nuclear
               Performing Control Room                      power, test and 
               Activities                                   research reactors,
                                                            and all licensed 
OL = Operating License
CP = Construction Permit 
Page Last Reviewed/Updated Friday, May 22, 2015