[en] The step-by-step approach which chooses detailed investigation area(s) from the preliminary investigations area(s) in the volunteer sites is adopted on the high-level radioactive waste disposal in JAPAN. It's requested at the stage of chooses detailed investigation area that there are few fears that surf zone and groundwater stream exert bad influence on disposal facility as well as stability of the geological environment. In order to evaluate influence of groundwater stream, it is necessary to evaluate of total performance of disposal system with limited information from preliminary investigations and several design options which have been assumed on the generic geological environment. For a rational procedure of total system evaluation, it is essential to arrange of known information of the former performance evaluation, and so, when same part of those information was changed, we become able to pick a scenario, models, parameters with a possibility which changes out by tracing these information. In this study, as a first step, we carried out make a methodology to structure a flow of a series of information from a geological survey result in detail and until performance evaluation. We tried to make a structuralization of known information by base on this methodology. And, we discussed realistic performance of over-pack by tracing this structured information. (author)