Speaker
Description
The transport of radioactive material is governed by stringent safety requirements defined in the IAEA regulations SSR-6. These requirements, especially the thermal and mechanical accident conditions, originate largely from concepts established in the 1960s and have remained essentially unchanged with respect to key thermal boundary conditions. At the same time, the rapid introduction of battery-electric and hydrogen-fueled vehicles into heavy-duty freight and dangerous goods transport is altering the boundary conditions of transport accidents. This raises a critical question: do today’s regulatory test requirements, such as the regulatory 800°C/30 minute thermal test, remain sufficiently conservative for accidents involving vehicles with alternative propulsion technologies?
Battery fires present specific challenges due to the properties of lithium-ion cells widely used in electric vehicles. In addition, other battery chemistries, such as NMC (Nickel-Manganese-Cobalt oxide), LFP (Lithium iron phosphate), and NCA/LTO (Nickel-Cobalt-Aluminium oxide / Lithium-titanate oxide) must be considered, as they are increasingly deployed across diverse transport applications. Electrolytes are highly flammable; thermal runaway can trigger cascading reactions; toxic and corrosive gases may be released. Unlike conventional fuel fires, such events can last well beyond 30 minutes and may reignite after seeming extinction, creating complex risks for emergency response and for the integrity of packages containing radioactive material. These characteristics call into question whether current thermal test specifications sufficiently represent real accident conditions involving battery-powered vehicles.
Hydrogen-fueled vehicles introduce additional hazards. Accidental releases can form explosive mixtures; ignitions may lead to intense jet fires or explosions with high radiative heat fluxes. In proximity to packages, such events could generate thermal loads and transient pressure effects that are not explicitly captured by the current regulatory test envelope. Beyond peak temperature and exposure time, parameters emphasized in the IAEA Advisory Material SSG-26 such as emissivity, absorptivity, heat flux and energy density of the involved fuels are decisive for the net heat input into a package and should therefore be assessed against realistic accident scenarios.
To close this gap, it is necessary to initiate a research program that investigates vehicle fire scenarios with the safety assessment of packaging for radioactive material under transport accident conditions. This necessary work must take into account the development of conservative accident scenarios reflecting different battery chemistries and capacities, as well as large-scale experimental investigations using calorimetric reference containers and instrumented test setups to quantify heat fluxes, temperatures, radiation intensities, and propagation/reignition phenomena.
In conclusion, the ongoing transformation of transport systems through electrification and hydrogen use necessitates proactive evaluation of their implications for the safe transport of radioactive material. Notably, there are currently no experimental investigations of accidents involving transport vehicles with alternative propulsion in which the dangerous goods - the package and its loading - have been the central focus rather than the vehicle itself. A necessary research project must aim to assess the relevance of the IAEA's existing transport testing requirements with regard to these new risks and, if necessary, propose changes or supplementary measures. Furthermore, such a program must be deliberately designed so that its methods, data sets, and benchmarks can also be applied to the assessment of other classes of dangerous goods outside radioactive materials by transferring heat inputs and exposure histories to other packaging types for other dangerous goods. By predicting the potential effects of battery and hydrogen fires, the Community can ensure that regulatory requirements continue to provide comprehensive protection, thereby maintaining the high level of safety in the transport of dangerous goods in a rapidly changing technological landscape.
