The neutrino is one of the most enigmatic ingredient of the standard model of particle physics. Because of its weak interaction with matter and despite enormous experimental progress, its nature and its fundamental properties remain unknown: Dirac / Majorana, CP violation, absolute mass scale, other flavors... Recent results from the t13 experiments Double Chooz, Daya Bay and RENO have uncovered an intriguing excess of events detected in the 4-6 MeV reconstructed energy range with respect to predictions. This spectral distortion may be a suggestion of discrepancies in models of antineutrino production in reactors. Moreover, three independent experimental anomalies (reactor anomaly, Gallium and LSND/ MiniBooNE) support the hypothesis of the existence of a new neutrino family, called sterile because not interacting through weak interaction. In this context, new data from a precise pure U235 Antineutrino spectrum are needed to resolve this open issue and to clarify the reactor anomaly. The SoLid project is an unique opportunity for the community to obtain sufficiently large and accurate data of neutrino flux at very short distance from a nuclear reactor, and then provide a reference measurement of pure 235U, essential for neutrino flux predictions used in current and future neutrino measurements. It proposes to confirm or refute the anomaly reactor and test ultimately the fourth sterile flavor. The strength of the SoLid proposal relies on both the antineutrino source and the technology of detection, which are unique. The experience takes place at BR2 research reactor of SCK-CEN (Mol, Belgium). It allows oscillation measurements at distance varying from 5.5 to 12 m from the core. In addition to this large range, the site is distinguished by its exceptionally low background environment and by having no-access to site constraint. The detector is based on an innovative technology of neutron detector, finely segmented. The use of 6LiF: ZnS layers allows a distinct discrimination of the neutron signal. In addition, the segmentation allows to locate the antineutrinos interactions and then effectively reject significant background sources. Combined with the favorable environment at BR2, our experiment provides an unprecedented sensitivity. Early 2015 a large-scale module 288kg (SM1) has been built and took “reactor ON” data during several days. This systems clearly demonstrates the capabilities of the segmented design of the detector, when combined with sophisticated data analysis techniques, leads to gains of orders of magnitude in background rejection. The physics run, with the full detector, will begin in October 2016 for a duration of two years minimum.This project is led by an international collaboration composed of eleven laboratories involving fifty physicists. Since the beginning, the three partners, Subatech, LAL and LPC have key contributions to the project: mechanical design, BR2 modelization, antineutrino spectra, Geant4/MCNP simulations and data analysis. This strong involvement allowed the coordinator to take responsablity of the SoLid analysis. Our proposal is to build 10 detection planes (320 kg) to increase the fiducial mass and the detector length, allowing us to probe the lower Dm2 phase space region. The French groups foresee to lead several specific studies into the oscillation framework to effectively probe the anomaly reactor, but also, comparing the pure U235 spectrum measured at BR2 with the data coming from the Double Chooz near detector to get an first insight in the “ 5 MeV bump” understanding. This specific contribution will consolidate our leadership in a experiment that promises to settle the question about the existence of sterile neutrino. In the longer term and for the international neutrino community, more precise neutrino flux measurements will allow to push the precision for future experiments.