Post-Fukushima complementary safety assessments extended to transport

Following the accident that occurred on the Fukushima Daiichi nuclear power plant on 11^th March 2011, the ASN (French Competent Authority) required the French nuclear operators to perform Complementary Safety Assessments (CSAs) of their facilities. The CSAs evaluate the capacity of French nuclear facilities to withstand extreme situations beyond design basis assumptions. During TRANSSC 24 in 2012, the 28 issues raised after the Fukushima accident were examined with regards to the IAEA SSR-6 transport regulations in order to draw lessons relevant for the transport of radioactive material. During the Technical Meeting on the Environment of Packages in transport, organized by the IAEA in July 2013 (TM 44891), it was underlined that emergency preparedness in transport was an urgent matter to be addressed. In 2013, ASN extended the CSA concept to the transport of radioactive materials. In this framework, IRSN (French Technical Support Organization) was requested to analyse: the current state of knowledge on the behavior of packages facing hazards of extreme intensity or having characteristics different from the test conditions defined by the IAEA SSR-6 standards; the opportunity and means to complete this knowledge by identifying potential credible accident beyond regulatory limits in order to initiate reflections related to emergency preparedness. IRSN considers that current regulatory requirements cover a large number of conceivable accidental situations. Nevertheless, there exist a limited number of scenarios that could lead, for some packages, to important radiological consequences. It was also concluded that potential risks induced by those scenarios could be reduced by implementing one of the following measures: a marginal strengthening of the regulations in particular cases; strengthening of local regulations in the case of specific infrastructures; operational measures such as excluding specific itineraries; special provisions for emergency response when above solutions are not suited to package design or to intended operations. (author)