The WE-NET project started its phase 2 program from FY1999 and it will last for 5 years. Various R&D is carried out for future establishment of 'World Energy Network System" and for early introduction of dispersed use of hydrogen. The aim of the safety studies in Phase 2 is to provide evaluation tool for safety assessment and data for risk assessment of above systems. In order to clarify the key phenomena related to hydrogen explosion, the fbllowing experiments are planned. They are leakage experiment of liquid hydrogen and explosion experiment of hydrogen / air mixture. In the leakage experiment, extension of liquid surface, evaporation and atmospheric dispersion of leaked hydrogen will be obtained to clarify the behavior of hydrogen cloud. In this paper, we will show the R&D activities on safety for the WE-NET project and the small-scale leakage experiment carried out in 1999.