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 mechanisms identified, licensees can more accurately monitor the condition of critical plant cables, assess their operating condition, and implement corrective actions to manage aging and degradation in those cables that are found to be experiencing stressors and aging/degradation rates beyond specified design conditions. The realistic and timely assessment of cable condition is the best means for managing cable degradation and avoiding unexpected early cable failures. Sections 3 and 4.5 of NUREG/CR-7000, “Essential Elements of an Electric Cable Condition Monitoring Program,” issued January 2010 (Ref. 6), provide guidance on the selection of electric cable condition monitoring techniques. Licensees can use a number of monitoring techniques to evaluate cable condition. A combination of monitoring techniques may be needed to validate cable performance. Some of the typical condition monitoring techniques and inspection methods that have been or are being used for cable condition monitoring include those described below, which are recommended for use when appropriate. 1. Direct Current High-Potential Test (dc High Voltage) The direct current (dc) high-potential test (HPT) is a pass/fail test applicable to medium-voltage power cables and all insulation and jacket materials. Aging mechanisms detected by the HPT comprise DG-1240, Page 5 thermally induced embrittlement and cracking, radiation-induced embrittlement and cracking, mechanical damage, water treeing, moisture intrusion, and surface contamination. Advantages associated with the HPT test are that it is relatively easy to perform, it does not require access to the entire length of the cable, and the test can potentially detect degradation sites before failure in service. The disadvantages of HPT are that the cable must be disconnected to perform the test and the high voltages involved during testing may damage the cable insulation. Recent research by the Electric Power Research Institute (EPRI) on