[en] The Sixth Case Study is a postclosure safety assessment of a deep geological repository for used CANDU fuel at a hypothetical site on the Canadian Shield. The hypothetical site and watershed areas are the same as in the Fourth Case Study but the geosphere properties, e.g., the fracture network, are different, and the repository location is different. The repository is placed at a depth of 500m as a design assumption. The Sixth Case Study also differs from the Fourth Case Study in that it considers the smaller Mark II reference container. The Mark II container has an outer copper coating for corrosion protection, an inner steel vessel for structural support, and capacity to hold 48 CANDU fuel bundles. These containers are pre-installed into bentonite buffer boxes, and then stacked in emplacement rooms in the repository. One purpose of the Sixth Case Study is to investigate the safety implications of this updated engineered barrier system based on the Mark II container. The safety assessment of a repository must consider a broad range of factors that could potentially affect the behaviour of the repository, the release of contaminants, and the repository environment over the periods of interest. These factors may be features of the repository or site (e.g., waste type, repository depth), events (e.g., earthquakes, climate change) or processes (e.g., sorption), and are known collectively as FEPs. They are used as input for scenario identification and subsequent conceptual model development for the safety assessment. However, not all potential FEPs are necessarily included in a given safety assessment. This report provides a structured and comprehensive list of possible FEPs relevant to the Sixth Case Study design and site. For each FEP, this report: provides a brief description of the FEP; discusses its relevance to the Sixth Case Study repository system; and identifies the scenarios where relevant FEPs are considered within the conceptual models developed for the Sixth Case Study. The development of a safety case for a site-specific safety assessment would proceed in stages from conceptual to detailed studies. The Sixth Case Study is a scoping study and is based on a hypothetical repository and site. The present FEPs assessment is representative of the level of information and analysis that would be available during the early stages of siting. (author)