				Search Options
Index \| Site Map \| FAQ \| Facility Info \| Reading Rm \| New \| Help \| Glossary \| Contact Us

Cable Insulation Resistance Measurements Made During Cable Fire Tests (NUREG/CR-6776)

On this page:

Publication Information
Abstract

Download complete document

The following links on this page are to documents in Adobe Portable Document Format (PDF). See our Plugins, Viewers, and Other Tools page for more information. For successful viewing of PDF documents on our site please be sure to use the latest version of Adobe.

NUREG/CR-6776 (PDF - 5.6 KB)

Publication Information

Manuscript Completed: April 2002
Date Published: June 2002

Prepared by
F. J. Wyant, S. P. Nowlen

Sandia National Laboratories
P.O. Box 5800
Albuquerque, NM 87185-0744

H. W. Woods, NRC Project Manager

Prepared for
Division of Risk Analysis and Applications
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
NRC Job Code Y6037

Availability Notice

Abstract

An insulation resistance diagnostic system was recently developed and exercised during a series of cable fire tests sponsored by the commercial U.S. nuclear industry. This insulation resistance measurement system was able to identify and quantify the changes in insulation resistance occurring between the separate conductors and the conductors to ground in cable bundles as they were being exposed to fires. Eighteen separate fire tests were conducted during the period January through May 2001 and included a variety of cable and fire exposure conditions. The insulation resistance measurement system was operated at a 120 VAC input to the conductors for 14 of those test runs and at 100 VDC input for three of the runs. One test was run with the insulation resistance measurement system providing 24 VDC to two separate instrument cables being exposed to the fire. The results obtained by the insulation resistance measurement system during these tests showed that cables will fail during a fire in one of three ways: by internal shorting of the conductors in a multiconductor cable, by shorting of the conductors in different cables bundled together, or by individual conductors shorting to ground. No incidents of fire-induced open circuits were found to have occurred during any of these tests. A mockup of a simple 4 to 20 mA DC current loop instrument circuit was included in six of the later tests. The intent was to investigate the potential of misleading or loss of instrument indication from fire damage to the signal cable. This report provides an analysis of the insulation resistance data and current loop results for the 18 tests run in the industry test program.