Natural tracer profiles across argillaceous formations : the CLAYTRAC project This technical report describes the results of the Nuclear Energy Agencys CLAYTRAC project in which natural tracer data from nine sites was evaluated to assess potential impacts of disposal of radiological waste in geological repositories. It&nbsp;shows scientific information from numerous sites and applies robust analytical methods to improve the understanding of radionuclide migration and evolution of sites for deep geological disposal. These results improve the understanding of sites and thus the confidence in safety for geological disposal of radioactive waste