A computer code has been written to predict pressure on the shell side of a steam generator during a large scale sodium-water reaction. A typical pressure transient has two main features. An initial pressure spike is followed by a secondary pressure pulse whose amplitude is a function of the inertia forces governing the growth of the hydrogen bubble. Unlike the primary pressure spike which lasts a very short time, the secondary pulse can last for a long time and must be considered a steady-state pressure acting on the shell. Rupture disks under sodium may not provide an effective means of relieving the secondary pressure pulse unless the sodium-water reaction occurs close enough to the disk to cause its rapid failure. It is concluded that both superheater and evaporator units of a reference steam generator design can withstand the pressure transient associated with the sodium-water reaction resulting from a guillotine failure of a single heat transfer tube.