This publication reports on the results of an IAEA coordinated research project (CRP) on benchmarking severe accident computer codes for heavy water reactor applications. The CRP scope included the identification and selection of a severe accident sequence, selection of appropriate geometrical and boundary conditions, conduct of benchmark analyses, comparison of all simulation results, evaluation of the computer code capabilities to predict important severe accident phenomena and core damage progression, and the proposal of code improvements and/or new experiments to reduce uncertainties. The summary report provides a comparison of key results for the selected Station Blackout (SBO) scenario, obtained from five participating States and concludes with lessons learned and recommendations for future activities.