In the framework of Spent Fuel Pools lifetime studies, an investigation of the concrete degradation in aqueous boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in a boric acid medium. A well-tested methodology for testing cementitious materials degradation in other solutions (water, sulfate solution) was applied. This methodology was based on an experimental study and computational modeling. The degradation experiments were carried out for three to eight months in 2400ppm boric acid solution. Aggressive solution conditions were maintained by pH regulation and periodical renewal. Characterization concerned the composition of the degradation solution during the experiments, as well as the mineralogical evolution of the degraded cementitious materials at the end of the experiments. Solution analysis was performed by ionic-chromatography and solid characterizations were carried out by the means of XRD and SEM observations. The study of the Portland cement paste degradation shows that the leaching mechanism is driven by diffusion. The degradation kinetics in boric acid is higher than the one in pure water. Reactive transport numerical simulations are carried out with HYTEC platform to be compared with experimental results. The calculations results reproduce the four zones composing the degraded Portland cement paste profile pattern that were identified experimentally. It is also demonstrated that the definition of the modelled system and of the external part of the degraded zone is key points.