[en] A recently developed sensitivity theory for nonlinear systems with responses defined at critical points, e.g. maxima, minima, or saddle points, of a function of the system's state variables and parameters is applied to a protected transient with scram on high power level in the Fast Flux Test Facility. The single-phase segment of the fast reactor safety code MELT-III B is used to model this transient. Two responses of practical importance, viz. The maximum fuel temperature in the hot channel, and the maximum normalized reactor power level, are considered. For the purposes of sensitivity analysis, a complete characterization of such responses requires consideration of both the numerical value of the response at the maximum, and the location in phase-space where the maximum occurs. This is because variations in the system parameters alter not only the value at this maximum but also alter the location of the maximum in phase-space