The adequacy of the containment of fast reactors has been traditionally evaluated by analyzing the response of the containment to a spectrum of core disruptive accidents. The current approach in the U.S. is to consider fast reactor response to accidents in terms of four lines of assurance (LOAs). Thus, LOA-1 is to prevent accidents, LOA-2 is to limit core damage, LOA-3 is to control accident progression and LOA-4 is to attenuate radiological consequences. Thus, the programs on the adequacy of containment response fall into LOA-3. Significant programs to evaluate the response of the containment to core disruptive accidents and, thereby, to assure control of accident progression are in progress. These include evaluating the mechanical response of the primary system to core disruptive accidents and evaluating the thermal response of the reactor structures to core melting, including the effects this causes on the secondary containment. The analysis of structural response employs calculated pressure-volume-time loading functions. The results of the analyses establish the response of the containment to the prescribed loadings. The analysis of thermal response requires an assessment of the distribution and state of the fuel, fission products and activated materials from accident initiation to final disposition in a stable configuration
