The present article describes the preliminary design studies for PETALE (Programme d'Etude en Transmission de l'Acier Lourd et ses Elements), an oncoming experimental program in the CROCUS reactor. Within the framework of the Venus-Eole-Proteus collaboration, PETALE continues the nuclear data validation efforts required for modeling GEN-111 pressurized water reactors with heavy steel reflectors. The inelastic scattering cross sections at around 1 MeV of iron -56, as well as nickel and chromium isotopes, will be studied separately. The water reflector will be replaced successively by sheets of stainless steel alloy and pure metals iron, nickel, and chromium. Data will be extracted from two sources: the measured neutron flux attenuation using adequate dosimetry and possibly fission chambers in the metal reflector and from the criticality effects of these reflectors. PETALE will also be used with nuclear data adjustment methods because, as a separated and elemental integral experiment, it allows the limiting of compensation effects in the nuclear data adjustments. A parametric study has been carried out with MCNPX for assessing the optimal configuration and the feasibility of the experiments. This study is the first step toward optimizing the global sensitivity of the experiments to the reactions in the energy range of interest, thus assessing the measurements' target uncertainties and preparing further use of the program results.