Document: NRC Regulatory Guide
Document ID: 8e45dce1-e1e7-4415-b1dd-7e2a610e545b
Document Type: regulatory_guide
Title: Fire Protection for Nuclear Power Plants (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2023/ML20231A835.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.189
CFR Part: 
CFR Title: 

Content:
volts (V) direct current (DC)). Since cable voltages used for ANI circuit integrity tests do not replicate cable operating voltages, loss of cable insulation conditions can exist during the fire test without a dead short occurring. It is expected that if the cables were at rated power and current, a fault would propagate. The use of circuit integrity monitoring during the fire endurance test is not a valid method for demonstrating that the protected shutdown circuits are capable of performing their required function during and after the test fire exposure. Therefore, the NRC does not require circuit integrity monitoring using the ANI criteria to satisfy its acceptance criteria for fire barrier qualification. The approaches described below are acceptable for evaluating cable functionality. B-3.1 Use of Environmental Qualification Data Comparison of the fire barrier internal time-temperature profile measured during the fire endurance test to existing cable performance data, such as data from EQ tests, may be used as a method for demonstrating cable functionality. EQ testing is typically performed to rigorous conditions, including rated voltage and current. When the EQ test time-temperature profile is correlated to the fire test time-temperature profile, the EQ test data provide a viable mechanism to ensure cable functionality. A large body of EQ test data for many cable types exists today. The use of EQ data represents a cost-effective approach for addressing cable functionality for fire tests for those cases in which the limit of 181 degrees C (325 degrees F) is exceeded. A comparison of fire test temperature profiles to existing EQ and loss-of-coolant accident test results or air oven test results is an acceptable approach to demonstrating cable functionality, provided that the subject analysis incorporates the anticipated temperature rise caused by the self-heating effects of installed power cables with the fire test results. B-3.2 Cable Insulation Tests The