Structural Materials Analyses of the Newhall Pass Tunnel Fire, 2007 (NUREG/CR-7101)

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Publication Information

Manuscript Completed: June 2011
Date Published: June 2011

Prepared by:
K. Axler¹
T.S. Mintz¹
K. Das¹
J. Huczek²

Center for Nuclear Waste Regulatory Analyses¹
Southwest Research Institute^®2
San Antonio, Texas

C. Bajwa, NRC Project Manager

Office of Nuclear Material Safety and Safeguards
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

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Abstract

On October 12, 2007, a major fire started at approximately 10:40 p.m. in the Newhall Pass tunnel near Santa Clarita, California. The tunnel fire was a result of an accident involving 34 vehicles in and around the Newhall Pass tunnel. One of the vehicles caught on fire and began to ignite the other vehicles in the tunnel. It was reported that smoke appeared to be emanating from the entrance of the tunnel while fire was visible at the exit within 15 minutes of its start. Material samples were recovered from five of the incinerated vehicles. The main objective of the work reported in this report was to examine the collected samples and estimate the temperature reached during the fire. This was determined by evaluating melting points, solid-state transformations, and thermally induced degradation. The materials analysis evaluated many melted aluminum samples, which indicated the temperature reached at least 560°C [1,040°F] at various locations in the tunnel. At other locations, hardness analyses of graded bolts indicated the temperature reached at least 800°C [1,470°F] in one of the vehicles located outside the tunnel. The results of the other bolts for vehicles in the tunnel had reach lower temperature below 750°C [1,380°F]. One brass sample showed incipient melting, which indicated that the temperature at this location reached at least 880°C [1,620°F].