In this paper, we consider the problem of the optimization of the inspection intervals of the High Pressure Injection System (HPIS) of a Pressurized Water Reactor (PWR). For its solution, we investigate the use of Differential Evolution (DE) and compare it to another popular Evolutionary Algorithm (EA), the Genetic Algorithm (GA). In the comparison, we look in particular at the computation time and at the characteristics of the Pareto frontier. The problem is first treated as a single-objective optimization (SO) and then as a multi-objective optimization (MO). For this latter, a Multi-Objective Differential Evolution (MODE) code has been purposely developed, in Matlab.