Document: NRC Regulatory Guide
Document ID: 9547afbc-5a01-4bff-a41f-8300f5ba922b
Document Type: regulatory_guide
Title: Condition Monitoring Techniques for Electric Cables Used in Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1007/ML100760364.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.218
CFR Part: 
CFR Title: 

Content:
Domain Reflectometry The time domain reflectometry (TDR) test is a diagnostic test that can be implemented on low- and medium-voltage cables and all types of cable insulation and jacket materials. The TDR test is able to detect aging mechanisms such as thermally induced cracking, radiation-induced cracking, and severe mechanical damage. The TDR test can also identify the presence of water and its location along a cable run, the location and severity of electrical faults, and the location and severity of insulation damage. Advantages of the TDR test are that it provides useful information for identifying and locating potential defects and discontinuities in a cable that may indicate severe insulation degradation or impending cable fault, it is nondestructive, it can be performed in situ from one end of a cable, and data can be trended against a baseline reflectogram. Disadvantages are that the end terminations of the cable must be disconnected to perform the test; training and experience are required for best results; and transient conditions, such as immersion, are only detectable when present during the TDR test. 10. Line Resonance Analysis The line resonance analysis (LIRA) test is a diagnostic test that is applicable to low- and medium- voltage cables and all types of cable insulation and jacket materials. The LIRA test can detect aging mechanisms such as thermally induced embrittlement and cracking, radiation-induced embrittlement and cracking, and severe mechanical damage. DG-1240, Page 8 Advantages of the LIRA test are that it can be performed in situ without disconnecting the cable, the test requires only a single access point, the analysis of results can account for the effects of loads attached to the cable, and it can accurately identify the site of localized degradation. Disadvantages are that the test is not simple to perform or interpret, and training and experience are needed to obtain meaningful results. 11. Infrared Imaging Thermography The infrared