Accurate prediction of source term and modelling of severe accident progression by severe accident analysis codes is integral to the safe operation of water cooled reactors in both developing and developed Member States. The source term released to the environment during severe accidents, calculated by these codes, is utilized by specialized atmospheric transport codes to evaluate the transport of radionuclides in the environment. Though severe accident codes are comprehensively validated based on experiments, there remains disagreement among calculations performed using different codes for the same scenarios. Such differences and their causes are being explored by a number of organizations, including cooperation by developers through code to code benchmarks. Furthermore, severe accident phenomena model improvements are being made with insights from experiments and with the development of models to account for previously less understood phenomena. This publication summarizes the current status of severe accident analysis codes and recommends areas for research and development. The information is detailed in terms of major findings, identified gaps, and recommended future actions.