United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 86-104: Unqualified Butt Splice Connectors Identified in Qualified Penetrations

                                                            SSINS NO.:  6835
                                                            IN 86-104 

                                UNITED STATES
                           WASHINGTON, D.C. 20555

                              December 16, 1986

                                   IDENTIFIED IN QUALIFIED PENETRATIONS 

All pressurized and boiling-water reactor facilities holding an operating 
license or a construction permit. 


This notice is to alert recipients to unqualified butt splice connectors 
supplied by General Electric (GE) in conjunction with qualified F-01 series 
penetration enclosures. These connectors failed during a recent 
environmental qualification test performed by Wyle Laboratories. It is 
suggested that recipients review this information for applicability to their 
facility and consider actions, if appropriate, to preclude occurrence of 
similar problems. Suggestions contained in this notice do not constitute NRC 
requirements; therefore, no specific action or written response is required. 

Description of Circumstances: 

During an NRC equipment qualification (EQ) inspection at Dresden Nuclear 
Power Station, May 19-23, 1986, a deficiency was discovered concerning a 
lack of similarity between tested and installed nylon insulated butt splices 
in EQ qualified GE electrical penetrations. Commonwealth Edison sent four 
sample splices removed from Quad Cities Nuclear Power Station to Wyle 
Laboratory to further substantiate their qualification for use in a harsh 
environment. These splices were identical to those installed at Dresden. 
During the testing performed at Wyle Laboratory December 4-5, 1986, all four 
samples exhibited excessive leakage currents to ground when exposed to a 
steam environment. Commonwealth Edison consequently declared the splices 
unqualified and shut down its Quad Cities Unit 1 to rework the splices by 
wrapping them with previously qualified tape. Dresden Unit 2 has similarly 
reworked the splices by wrapping them with tape. Duane Arnold Energy Center 
also has commenced a shutdown in order to make repairs. 


The splices in question were supplied by GE as part of their F-01 
penetration assemblies. GE obtained the splices from three different 
manufacturers: Amp, Thomas and Betts, and Hollinsworth. The splices in 
question are nylon insulated  


                                                       IN 86-104 
                                                       December 16, 1986 
                                                       Page 2 of 2 

butt splices and most appear to be for 12-to-22 gauge conductors although 
other sizes may be installed as well. The splices from the three 
manufacturers are almost identical in design and are all manufactured using 
either Zytel-42 or Celanese-1200 nylon tubing over a metal crimp connector. 

The splices tested at Wyle were manufactured by Amp and had been removed 
from Quad Cities where they had been exposed to approximately 12 years of 
aging (thermal and radiation). Wyle also subjected the samples to aging and 
radiation sufficient to add an additional year. After this aging and 
irradiation, the samples were inspected and tested for insulation 
resistance. The samples showed no sign of fatigue and exhibited a high 
insulation resistance. The samples were then put into a 
loss-of-coolant-accident (LOCA) chamber and energized for the start of the 
LOCA test. Two samples were energized with 528 volts and two samples were 
energized with 132 volts. During the preheat of the LOCA chamber and before 
the actual LOCA test, one of the 528-volt samples began shorting to ground 
and blew its fuse. At this point the temperature in the chamber had reached 
only 150F. The test was continued with two other specimens blowing 
fuses at the 20-second point and at the 2-hour, 23-minute point of the test. 
The fourth sample finished the test, but excessive leakage currents were 

The short circuits that occurred appeared to start by condensation entering 
the splice between the wire insulation and the nylon tubing. The arcing 
caused insulation degradation that then allowed arcs to pass through the 
insulation to the enclosure. 

The NRC is currently evaluating additional data pertaining to butt splice 
connectors and may be issuing additional information on this subject in the 
near future. 

No written response to this notice is required. If you have any questions 
regarding this notice, 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:  J. Jacobson 
                    (301) 492-8845 

List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Friday, May 22, 2015