The work presented in this report aims to study the sensitivity of nuclear heating calculations in Pressurized Water Reactors (PWRs) to the nuclear data library used as calculation input. Accurate understanding and prediction (by means of calculations) of spatial distributions of nuclear heating in the different PWR materials is one of the majors stakes for PWR design and safety studies. Nuclear heating directly affects fuel and material temperatures and is a main parameter for the design of the different components of a reactor. Nuclear heating also affects the location of the power distribution “hot spot” of a reactor which is crucial in safety studies for proper design and sizing of the reactor.