Most of the actors involved in severe accident research in Europe, plus Canada, Korea and the United States (41 partners), will network in SARNET2 (Severe Accident Research NETwork of Excellence - Phase 2) their capacities of research in order to resolve important pending issues on postulated severe accidents of existing and future Nuclear Power Plants (NPPs). The project has been defined in order to optimise the use of the available means and to constitute a sustainable consortium in which common research programmes and a common computer tool to predict NPP behaviour during a postulated severe accident (ASTEC integral code) are developed. With this aim, the SARNET2 partners contribute to a Joint Programme of Activities, which consists of: - Maintaining and improving an advanced communication tool (developed during SARNET Phase 1) for accessing all project information, fostering exchange of information, and managing documents; - Harmonizing and re-orienting the research programmes, and defining new ones; - Performing experimental programmes on high priority issues, defined during SARNET Phase 1; - Analyzing experimental results in order to elaborate a common understanding of relevant phenomena; - Developing the ASTEC code (including its applicability to all types of European NPPs), which capitalizes in terms of physical models the knowledge produced within SARNET2; - Developing Scientific Databases, in which all the results of research programmes are stored in a common format (DATANET); - Developing education courses on severe accidents for students and researchers, and training courses for specialists; - Promoting personnel mobility amongst various European organizations; - Organizing yearly a large international conference on Severe Accident research (ERMSAR). After the first phase (2004-2008), and the four-year proposed second phase, co-funded by the EC, the network will evolve toward self-sustainability: a legal entity will be created.