United States Nuclear Regulatory Commission - Protecting People and the Environment

Aging, Loss-of-Coolant Accident (LOCA), and High Potential Testing of Damaged Cables (NUREG/CR-6095, SAND93-1803)

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Publication Information

Manuscript Completed: January 1994
Date Published:
April 1994

Prepared by:
R.A. Vigil (SEA)
M.J. Jacobus (SNL)

Science and Engineering Associates, Inc. (SEA)
6100 Uptown Blvd, NE
Albuquerque, New Mexico 87110

Under Contract to:
Sandia National Laboratories (SNL)
P.O. Box 5800
Albuquerque, New Mexico 87185-5800
Operated by Sandia Corporation

Prepared for:
Division of Reactor Controls and Human Factors
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC FIN L-1903

Availability Notice

Abstract

Experiments were conducted to assess the effects of high potential testing of cables and to assess the survivability of aged and damaged cables under Loss-of-Coolant Accident (LOCA) conditions. High potential testing at 240 Vdc/mil on undamaged cables suggested that no damage was incurred on the selected virgin cables. During aging and LOCA testing, Okonite ethylene propylene rubber (EPR) cables with a bonded jacket experienced unexpected failures. The failures appear to be primarily related to the level of thermal aging and the presence of a bonded jacket that ages more rapidly than the insulation. For Brand Rex crosslinked polyolefin (XLPO) cables, the results suggest that 7 mils of insulation remaining should give the cables a high probability of surviving accident exposure following aging. The voltage necessary to detect when 7 mils of insulation remain on unaged Brand Rex cables is approximately 35 kVdc. This voltage level would almost certainly be unacceptable to a utility for use as a damage assessment tool. However, additional tests indicated that a 35 kVdc voltage application would not damage virgin Brand Rex cables when tested in water. Although two damaged Rockbestos silicone rubber cables also failed during the accident test, no correlation between failures and level of damage was apparent.

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