Important Note: This document describes post-closure safety calculations for a generic deep horizontal drillhole repository. The calculations are preliminary and do not derive from a specific geographic location or geological site. The layout and design of the repository represent only the general disposal concept as no site-specific characterization data or detailed technical designs are available. The conceptual and numerical models, as well as assumptions and parameters and their uncertainties, are reflective of this context. Generic calculations are a necessary step toward developing a comprehensive, site-specific safety analysis that will support the safety case of a deep horizontal drillhole repository in compliance with all applicable regulations.