[en] European R and D for Accelerator Driven System (ADS) design and fuel development in the 6th EC Framework Programme is driven by the Integrated Project EUROTRANS [1]. In EUROTRANS two ADS design routes are followed, the XT-ADS and the EFIT. The XT-ADS is designed to demonstrate the concept of ADS with a subcritical core combined with an accelerator. The longer-term EFIT development (European Facility for Industrial Transmutation) aims at a generic conceptual design of a full transmuter. This paper will concentrate on the EFIT core, which has a thermal power of about 400 MWth. The main goal of the EFIT design is to achieve an effective transmutation rate of the Minor Actinides (MAs) and respect important operational requirements as e.g. a low reactivity swing, a low power peaking, reasonable beam requirements and guarantee a high safety level. In order to have a sufficient subcriticality level, EFIT design is postulated to have a keff of 0.97. The risk of an accidental over-(the maximum) current does not exist in EFIT because, due to the very small burn-up reactivity swing, EFIT will work in the whole cycle with the maximum current allowed by the accelerator. A so-called 42-0 approach [2] is finally proposed by ENEA and adopted in the EFIT core design. With this 42-0 strategy, the EFIT core will be able to transmute about 42 kg/TWhth of MAs and keep a near zero net mass balance of Pu. The current EFIT core is loaded with a CERCER U-free fuel with MgO as the matrix. The 9Cr1MoVNb (T91) steel is used for the clad, which has a maximum temperature limitation of 550 C at the normal full power operation condition. Lead is used as the core coolant. It has an inlet temperature of 400 C and an outlet temperature of 480 C [3]. The temperature of 400 C at core inlet provides a margin to avoid lead freezing, and the temperature of only of 480 C at the core outlet offers many advantages in terms of reduced structure corrosion rates, improvement of the mechanical characteristics (making negligible creep of the structures), and reduces thermal shocks at transient conditions. Moreover at this 480 C nominal average core outlet temperature, the fuel clad temperature can be maintained below the limit of 550 C during the normal operation condition. Some core design data will be presented in the following section. For EFIT safety studies, the defence-in-depth concept has been applied [4]. The demonstration of the adequacy of the design with the safety objectives is structured along three basic conditions: (1) The Design Basis Conditions (DBC - structured into 4 Categories). The design of the plant results essentially from the analysis of these events. It must be shown that their consequences are very limited and, in any case, the risk of a whole core accident initialed by these events is very low. (2) Design Extension Conditions (DEC - limiting events, complex sequences and severe accidents) evaluated for licensing purposes independently of their occurrence frequency. The consequences of these accidents are analyzed and their consequences in the environment have to be demonstrated to be lower than the limiting release targets. (3) Residual Risk situation. The consequences of these situations are not analyzed since they are postulated to be unacceptable. The prevention measures regarding their occurrence have to be demonstrated to be sufficient. The safety principles and safety guidelines have been elaborated For EFIT within EUROTRANS and a comprehensive and representative list of transients has been established to test the safety behavior of the reactor plant. For innovative reactors such as EFIT, cliff-edge effects should be identified and excluded. For safety analyses, fuel parameter limits related to the different accidental categories have been determined on the basis of recent experimental evidences. Due to existing uncertainties, fuel melting or disintegration may only be allowed in the DEC category. In this paper, based on the current EFIT core design, a first transient analysis of the Unprotected Loss of Flow (ULOF) accident will be reported together with the steady state analysis performed by the SIMMER-III code [5, 6]. SIMMER-III is a two-dimensional, multi-velocity-field, multi-phase, multicomponent, Eulerian, fluid-dynamics code system coupled with a structure model including fuel-pins, hexcans etc., and a space-, time- and energy-dependent transport theory neutron dynamics model. The overall fluid-dynamics solution algorithm is based on a time-factorization approach, in which intra-cell interfacial area source terms, heat and mass transfers, and the momentum exchange functions are determined separately from inter-cell fluid convection. In addition, an analytical equation-of-state (EOS) model is available to close and complete the fluid-dynamics conservation equations. The code has originally been allocated in the severe accident domain of fast sodium cooled reactors. However, the philosophy behind the SIMMER development was to generate a versatile and flexible tool, applicable for the safety analysis of various reactor types with different neutron spectra and coolants, up to the new accelerator driven systems (ADS) for waste transmutation. (orig.)