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:
stem installed on a cable tray should be measured by placing thermocouples every 152 mm (6 in.) on the exterior surface of each tray’s side rails between the side rail and the fire barrier material. Internal raceway temperatures should be measured by a stranded AWG 8 bare copper conductor routed on the top of the cable tray rungs along the entire length and down the longitudinal center of the cable tray run with thermocouples installed every 152 mm (6 in.) along the length of the copper conductor. Thermocouples should be placed immediately adjacent to all structural members, supports, and barrier penetrations. c. Junction boxes: The temperature rise on the unexposed surface of a fire barrier system installed on junction boxes should be measured by placing thermocouples on either the inside or the outside of each junction box surface. Each junction box surface or face should have a minimum of one thermocouple, located at its geometric center. In addition, one thermocouple should be installed for every 0.09 m2 (1 ft2) of junction box surface area. These thermocouples should be located at the geometric centers of the 0.09-m2 (1-ft2) areas. At least one thermocouple should also be placed within 25 mm (1 in.) of each penetration connector/interface. d. Airdrops: The internal airdrop temperatures should be measured by a stranded AWG 8 bare copper conductor routed inside and along the entire length of the airdrop system with thermocouples installed every 152 mm (6 in.) along the length of the copper conductor. The copper conductor should be in proximity to the unexposed surface of the fire barrier material. Thermocouples should also be placed immediately adjacent to all supports and penetrations. B-1.3 Criteria for Averaging Temperatures Temperature conditions on the 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