Despite the accident prevention measures adopted in the nuclear power plants (NPP), some accident scenarios, in very low probability circumstances, may result in severe accidents (SA) with core melting, plant damage and subsequent dispersal of radioactive materials into the environment, thus constituting a hazard for the public health and for the environment. Large progress has been made since the 80’s thanks in particular to the Framework Programmes of the European Commission, but several issues still need research activities to reduce uncertainties and consolidate SA management plans. Facing the reduction of the national budgets on research on SA, it was judged necessary to better coordinate the national efforts to optimise the use of the available expertise and the experimental facilities in order to resolve the remaining issues for enhancing the safety of existing and future NPPs.
SARNET tackles the fragmentation that exists between the different research national programmes, notably in defining common research programmes and developing common computer tools and methodologies for safety assessment. The network comprises most of the actors involved in SA research in Europe, plus a few non-European important ones (USA, Canada, Korea). A few organizations are covering a wide range of competences though not complete, whereas others are specialized in very specific areas and thus complementarities are developing. The critical mass of competences for performing experiments needed in the SA domain, analysing them, developing models and integrating them into the ASTEC integral computer code, is achieved for most types of NPPs in Europe.
The ultimate aim is to ensure the long term self-sustainability of the network by a strong coordinating structure for work orientation in a “virtual centre of excellence”.

ASTEC

Since several years, the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN) and the German Gesellschaft für Anlagen und Reaktorsicherheit mbH (GRS) have been jointly developing a system of calculation codes, so-called “integral” code, ASTEC (Accident Source Term Evaluation Code) to simulate the complete scenario of a hypothetical severe accident in a nuclear water-cooled reactor, from the initial event until the possible radiological release of fission products out of the containment. It is used to define actions that prevent or mitigate the consequences of such accidents and improve protection of population in case of accident. Most of the organizations involved in SARNET contribute to the code assessment and improvements. ASTEC is now considered as the European reference SA code.