The aim of Task 4 was to review the background, to outline the current state-of-knowledge of the coupled THM issues related to performance and safety assessments of nuclear waste repositories, and to establish a consensus understanding and statements of the current state-of-knowledge in the subject area. The research performed including a literature review on the states-of-knowledge about coupled THM processes in geological systems and geoengineering related to radioactive waste disposal in geological media, and established a technical auditing system for detailed examination and analysis of scientific and engineering practices, such as Task 2 as a typical example, both the Kamaishi experiments and DECOVALEX II project modeling. In this way, a clear and rational method of auditing procedures, and establishing the importance and status of past and present information, could be clearly described in a specially designed format. Accordingly, interactive information exchange between the reviewers and research teams was enabled and the outcome presented in the final report. The technique was proved to be effective for review, evaluation and presenting scientific, engineering and management aspects of research projects—and has been applied in other research projects in international communities for GDRW, including the EC and other countries in Asia.