[en] Using Sequoyah as a representative plant, the CONTAIN severe accident analysis code has been employed to evaluate the ability of several proposed containment improvements to reduce the threat to containment integrity associated with direct containment heating (DCH) and hydrogen combustion in ice condenser plants during station blackout accidents. Calculations were performed using 4-cell, 6-cell, and 26-cell representations of the containment. Potential improvements considered included containment venting, improved igniter systems (including backup power supplies), containment inerting, subatmospheric containment, reduced ice condenser bypass, backup power supplies for the air return fans, and intentional depressurization of the reactor coolant system (RCS). The most effective improvements considered were inerting of the containment atmosphere, and the combination of depressurization of the RCS and provision of backup power for the igniter systems. Either of these approaches could substantially reduce, though perhaps not totally eliminate, the threat to containment integrity associated with DCH and hydrogen deflagrations. The other improvements considered offered at best only moderate mitigation, which would probably be insufficient to substantially alter the contribution of DCH to risk in PRAs such as those reported in NUREG-1150. 11 refs., 2 figs., 5 tabs