Abstract: Some codes have been introduced from western countries since 1980s, as an important tool for radioactive material transport consequence assessment. There isn't, however, a homemade code with independent intellectual property rights in China. Program design of code CRAMTRA in this respect is presented, with its physical model, flow chart and UML diagram included. This lays a solid basis for its code development.

Key words: Radioactive material, Transport, Code, Consequence assessment, Program design