[en] Results are reported of a sensitivity study conducted upon generic 312 and 412 Nuclear Steam Supply Systems (NSSS) and associated auxiliary systems which determine those system parameters that have the most effect on the results of a system transient following a main feedline rupture. Furthermore, it is shown that the system transient following a main feedline rupture assuming worst case initial conditions and assumptions meets the criteria set forth in the Standard Review Plan, Section 15.2.8. Based upon the results of this study, only the transient following a feedline rupture which assumes worst case initial conditions and assumptions with and without offsite power available will be presented in future Safety Analysis Reports