After four years of operation in the 6th Framework Programme (FP6) of Research and Development of the European Commission, the SARNET (Severe Accident Research NETwork of excellence) network has continued its activity between 2009 and 2013 with financial support of FP7 as the SARNET2 project. Forty-seven organisations (research, universities, industry, utilities, safety authorities and technical safety organizations) from 24 countries have networked their capacities to resolve the most important remaining uncertainties and safety issues on severe accidents in existing and future water-cooled nuclear power plants. The network, coordinated by IRSN (France), tackles the fragmentation that may still exist between the different national R&D programmes by defining common research programmes and developing common tools and methodologies for safety assessment. The overall work, involving about 250 researchers and 30 PhD students, represents an equivalence of 40 full-time persons per year. Most key European R&D actors are members and the network takes also benefit from the knowledge and work of important non-European organizations from USA, Canada, Korea, India and Japan. The collaborative work on corium, containment and source term phenomena has allowed a significant progress on the following 6 high-priority issues: corium/debris coolability, molten-core concrete-interaction, steam explosion, hydrogen combustion in containment, impact of oxidizing conditions on source term, and iodine chemistry. New experiments have been funded and performed on debris bed reflooding, molten-core-concrete-interactions and source term. Knowledge on severe accident phenomena and management was continuously produced through joint interpretation of past and new experiments, benchmark exercises between codes, state-of-the-art reports and elaboration of physical models. This knowledge was capitalized in common tools: ASTEC IRSN-GRS integral code for simulation of severe accidents through new physical models, and DATANET database through storage of experimental data and reports using the JRC STRESA tool (today 265 experiments in 43 facilities). Dissemination of knowledge was also an important part of the activities during the four years: three education courses for young researchers or students or for staff managers, edition of a textbook of 750 pages on severe accident phenomenology, mobility of researchers or students between the network partners, two ERMSAR periodic conferences (plus the next one in October 2013 under preparation) that are becoming the major worldwide conference on severe accident research, and more than 360 technical papers in conferences and scientific journals.