An Analysis of a Spent Fuel Transportation Cask Under Severe Fire Accident Conditions

Abstract

Title 10 of the Code of Federal Regulations Part 71 section 73(c)(4), (10 CFR 71.73(c)(4)) requires that transportation packages used to ship radioactive material must be designed to resist an engulfing fire of a 30 minute duration and prevent release of radioactive material to the environment. In July, 2001, a derailed train carrying hazardous materials caught fire in a railroad tunnel in Baltimore, Maryland, and burned for several days. Although the occurrence of a fire of such duration during the shipment of spent nuclear fuel is unlikely, questions were raised about the performance of spent nuclear fuel casks under conditions similar to those experienced in the Baltimore tunnel fire incident. The U.S. Nuclear Regulatory Commission evaluates the performance of spent fuel transportation casks under accident conditions. The National Transportation Safety Board is responsible for investigating railroad accidents and identifying the probable cause(s) and offers recommendations for safety improvements. They are currently investigating the Baltimore tunnel fire accident. This paper assesses the performance of a spent fuel transportation cask with a welded canister under severe fire conditions. The paper describes the analytic model used for the assessment and presents a discussion of the preliminary results.

Spent fuel transportation cask under accidental fire conditions: Numerical analysis of gas transport phenomena affecting heat transfer in shielding materials

“…More specifically, thermal analyses 3 are conducted in order to simulate the exposition of the cask to an accidental engulfing fire characterized by a radiative source at 800°C emitting for a time span of 30 minutes and to evaluate the maximum temperatures reached inside the cask as well as the heating kinetics. Such numerical simulations are usually performed on the basis of a 2D model of a transversal section (Bajwa, 2002) or a 3D model of the whole packaging (Bajwa et al, 2004), (Lo Frano et al, 2011), (Lo Frano et al, 2014), (Pugliese et al, 2010), with radiation boundary conditions to represent the heat flux exchanged between the fire and the cask, heat conduction in the solid parts of the system, in some cases partial melting of the content (Sanyal et al, 2011), or convection (natural or/and forced if a ventilation system is involved, mainly for storage casks (Alyokhina, 2018)) in the air volumes. Equivalence methods can be used to represent the complex multilayer structure of the cask wall and contents (including air gaps) (Xu et al, 2013), (Alyokhina and Kostikov, 2014).…”

A coupled thermal-drop impact analysis-based safety assessment of radioactive material cask

“…A FE simulation of a free drop test of a CASTOR cask with an artificial crack is described by Enderlein et al (2003). Bajwa and Rockville (2002) analyzed the thermal behavior of a cask under severe fire accident conditions. Sanyal et al (2011) carried out a comprehensive computational fluid dynamics analysis of the thermal behavior of melting of the lead under high Rayleigh number convection during the fire test, and investigated the substantial influence of natural convection on the thermal state and melting behavior of the lead.…”