Information Notice No. 86-104:Unqualified Butt Splice Connectors Identified in Qualified Penetrations
SSINS NO.: 6835
IN 86-104
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
December 16, 1986
Information Notice No. 86-104: UNQUALIFIED BUTT SPLICE CONNECTORS
IDENTIFIED IN QUALIFIED PENETRATIONS
Addressees:
All pressurized and boiling-water reactor facilities holding an operating
license or a construction permit.
Purpose:
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.
Discussion:
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
measured.
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
Attachment:
List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Tuesday, March 09, 2021