An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant Control Cabinets: Part II — Room Effects Tests (NUREG/CR-4527, SAND86-0336, Volume 2)

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Publication Information

Manuscript Completed: January 1988
Date Published: November 1988

Prepared by:
J.M. Chavez, S.P. Nowlen
Sandia National Laboratories
Albuquerque. New Mexico 87185
Operated by Sandia Corporation
for the U.S. Department of Energy
Under Contract No. DE-AC04-76DP00789

Prepared for:
Division of Engineering
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Under Memorandum of Understanding DOE 40-550-75

NRC FIN A-1010

Availability Notice

Abstract

This report presents the findings of the second part of a two-part series of full-scale electrical cabinet fire tests conducted by Sandia National Laboratories for the U.S. Nuclear Regulatory Commission. The first part of this test series investigated the effects of various cabinet parameters on a cabinet fire. The second part of the test series, described here, investigated the effects of such a fire on a large (18.3x12.2x6.1-m or 60x4Ox20-ft) enclosure.

Five tests involving a fire in a control cabinet were conducted under Part 2 of the test series. These tests investigated the effects of fuel type, cabinet configuration, and enclosure ventilation rate on the development of the enclosure environment. Although fires as large as 1300 kW resulted, enclosure peak temperatures (outside the fire plume itself) were typically less than 150 °C, with significant vertical thermal stratification observed. The most significant impact on the test enclosure environment was that dense smoke, in all cases, resulted in total obscuration of the enclosure within 6–15 min of fire ignition. Enclosure ventilation rates as high as 8 room air changes per hour were found to be ineffective in purging the smoke from this large enclosure. Similar obscuration problems had also been observed in the Part 1 tests, which utilized a smaller enclosure with ventilation rates as high as 15 room air changes per hour.