Analyses of historical rail accidents to identify accident parameters impacting transport of spent nuclear fuel

As a regulatory authority for the transportation of spent nuclear fuel (SNF) in the USA, the Nuclear Regulatory Commission requires that SNF transportation packages be designed to endure a fully engulfing fire with an average temperature of 800uC (1475uF) for 30 min, as prescribed in Title 10 of the Code of Federal Regulations Part 71. The work described in this paper was performed to support the Nuclear Regulatory Commission in determining the types of accident parameters that could produce a severe fire with the potential to fully engulf an SNF transportation package. This paper describes the process that was used to characterise the important features of rail accidents that would potentially lead to an SNF transport package being involved in a severe fire. Historical rail accidents involving all hazardous material (i.e. all nine classes of hazardous material) and long duration fires in the USA have been analysed using data from the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration. Parameters that were evaluated from these data include, but were not limited to, class of track where the accident occurred, class of hazardous material that was being transported and number of railcars involved in the fire. The data analysis revealed that in the past 34 years of rail transport, roughly 1800 accidents have led to the release of hazardous materials, resulting in a frequency of roughly one accident per 10 million freight train miles (Because all of the data were obtained in the USA, which still uses distance measured in miles, and the primary source is an extensive database from the Federal Railroad Administration that is also in reported in miles, the data in this paper are reported in miles rather than kilometres. Conversion of miles to kilometres is by multiplication of 1?61.). In the last 12 years, there have only been 20 accidents involving multiple car hazardous material releases that led to a fire. This results in an accident rate of 0?003 accidents per million freight train miles that involved multiple car releases and a fire. Out of all the accidents analysed, only one involved a railcar carrying class 7 (i.e. radioactive) hazardous material.