This publication covers the results of the coordinated research project on the Improvement of Safety Assessment Methodologies for Near Surface Disposal Facilities (ISAM), organized by the IAEA to improve and harmonize the approach to such safety assessment, which has resulted in development of the ISAM project methodology. The ISAM project involved the review and enhancement of post-closure safety assessment methodologies and tools for both existing and proposed near surface radioactive waste disposal facilities. The main objectives of the project were to: (a) provide a critical evaluation of the approaches and tools used in the post-closure safety assessment of proposed and existing near surface radioactive waste disposal facilities; (b) enhance the approaches and tools used; (c) build confidence in the approaches and tools used. In order to help achieve these objectives, the ISAM project paid particular attention to discussing, agreeing and setting down a safety assessment methodology. The ISAM project primarily focused on developing a consensus on the methodological aspects of safety assessment, but also gave considerable attention to illustrating the application of the methodology to three main types of disposal facilities (vault, RADON and borehole type disposal facilities).
