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:
e unexposed surfaces of the fire barrier material during the fire test will be determined by averaging the temperatures measured by the thermocouples installed in or on the raceway. To determine these temperature conditions, the thermocouples measuring similar areas of the fire barrier should be averaged together. Acceptance will be based on the individual averages. The following methods of averaging should be followed: a. Conduits: The thermocouples applied to the outside metal surface of the conduit should be averaged together. b. Cable trays: The thermocouples on each cable tray side rail should be averaged separately. For example, thermocouples placed on one side rail will be averaged separately from the other side rail. In addition, the temperature conditions measured by thermocouples on the bare copper conductor should be averaged separately from the side rails. c. Junction boxes: For junction boxes that have only one thermocouple on each junction box surface, the individual junction box surface thermocouples should be averaged together. For junction boxes that have more than one thermocouple on each junction box surface, the thermocouples on the individual junction box surfaces should be averaged together. d. Airdrops: The thermocouples placed on the copper conductor within the airdrop fire barrier should be averaged together. The average temperature of any thermocouple group should not exceed 139 degrees C (250 degrees F) above the unexposed side temperature within the fire barrier test specimen at the onset of the fire endurance test. In addition, the temperature of each individual thermocouple will be evaluated. DG-1359, Appendix B, Page B-5 Individual thermocouple conditions should not exceed the temperature rise of 139 degrees C (250 degrees F) by more than 30 percent. If a fire barrier test specimen without cables does not meet the average or maximum single point temperature criteria, the internal raceway temperature profile as measured by the