Effects of tunnel fires on behaviour of spent nuclear fuel casks

Abstract

As part of the Nuclear Regulatory Commission's (NRC) overall review of the performance of transportation casks under severe accident conditions, the NRC has undertaken a number of initiatives, including an examination of the Baltimore rail tunnel fire in 2001, and the Caldecott road tunnel fire in Oakland, California, in 1982. The NRC, working with the National Transportation Safety Board (NTSB), the National Institute of Standards and Technology (NIST), and Pacific Northwest National Laboratory (PNNL), performed analyses to evaluate the potential for a release of radioactive material from the transportation casks analysed for the Baltimore and Caldecott tunnel fire scenarios. Full details on this work have been published in NUREG/CR-6886, Rev. 1, 'Spent fuel transportation package response to the Baltimore Tunnel Fire Scenario' and NUREG/CR-6894, Rev. 1, 'Spent fuel transportation package response to the Caldecott Tunnel Fire Scenario'. This paper contains a summary of the results of these analyses. Most significantly, the staff found that for both tunnel fire events, a release of radioactive material from any of the casks analysed is unlikely, and that any potential release would be very small – less than an A2 for radionuclides of greatest concern.