An important part of our activity is dedicated to nuclear data, which are core parameters for reactor studies. We develop innovative tools to assess the impact of cross section uncertainties on core fuel evolution. On the experimental point of view, our studies concerned measurements of elastic scattering cross section of neutrons on light nucleus like Li and F, components of molten salts, at the PEREN-Neutrons facility. At present they concern fission product yield measurements for nucleus involved in the thorium fuel cycle, at Lohengrin facility at ILL.