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:
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 imaging thermography technique is a nondestructive, noncontact, electronically enhanced visual inspection technique for electrical equipment that is simple to perform and valuable in identifying potentially damaging service conditions where elevated temperatures are present. This technique is applicable to low- and medium-voltage cables or higher and all types of cable insulation and jacket materials. The infrared imaging test is able to detect aging mechanisms such as thermally induced embrittlement and cracking. Infrared imaging provides a useful tool for identifying temperature hotspots that could lead to accelerated degradation of electric cable systems or that indicate high-resistance electrical joints in electrical connectors and splices because of loosening, dirt or contamination, or corrosion. The instrument’s high-resolution temperature detection capabilities combined with image storage and analysis software make it possible to trend the thermal data obtained. Advantages of the infrared imaging thermography technique are that it is relatively easy to perform, properly corrected data identify the temperatures and location of hotspots, measurements can be made when the circuit is operating with a full load, data may be stored and trended with appropriate software, the test is nondestructive and nonintrusive, and it does not require the cable system under test to be disconnected. Disadvantages are that it requires training and experience for best results, measurements made when the circuit is operating at load can lead to safety concerns, high-end imagers and analysis software are expensive, and the cables and accessories to be monitored must be visually accessible. Further information describing the selection and performance of many different types of cable